Potato ranks fourth position in the world after wheat, rice and maize as non cereal food crop. Potato is probably the most popular food item in the Indian diet and India is one of the largest producers of potato. It is used in many ways like vegetable, potato wafers/chips, powder, finger chips etc. Potato tubers constitute a highly nutritious food. It provides carbohydrates, vitamin C, minerals, high quality protein and dietary fiber. Potato is a rich source of starch and it is consumed mainly for its calorific value, also contains phosphorus, calcium, iron and some vitamins. Boiling potatoes increases their protein content and almost doubles their calcium content. It is vastly consumed as a vegetable and is also used in various forms such as starch, flour, alcohol, and dextrin and livestock fodder. It is estimated that about 25 % of the potatoes, which are spoiled due to several reasons, may be saved by processing and preservation of various types of processed products. The potatoes can be processed for preservation and value addition in the form of wafers/ chips, powder, flakes, granules, canned slices. Potato granules are used for the preparation of various recipes, to add to vegetable and non vegetable recipes and to enhance the quantity as well as to enrich the food value. There is a huge potential for processed potato products such as potato flakes, potato powder, frozen potatoes, frozen French fries, potato chips/wafers are one of the most popular snack items consumed throughout world. International trade in potatoes and potato products still remains thin relative to production, as only around 6 percent of output is traded. High transport costs, including the cost of refrigeration, are major obstacles to a wider international marketplace. The industry is still growing at a rapid pace where French fries are showing the highest growth followed by potato chips and potato powder/flakes. It is by far the largest product category within snacks, with 85% of the total market revenue.
This book basically deals with origin, evolution, history and spread of potato, potato products, quality requirements for processing, morphological, size and shape, defects, biochemical, dry matter, reducing sugars, phenols, inheritance, morphological attributes, tuber shape, growth cracks, hollow heart, internal rust spots, greening, biochemical attributes, glycoalkaloids, dry matter, reducing sugars, enzymic browning, development of varieties for processing, areas suitable for growing processing potatoes, processing quality of Indian potato varieties, processed potato products, dehydrated products at village level, potato chips, french fries and flakes commercial production, grading manual for frozen French fried potatoes for frozen French fried potatoes, areas of production, varieties, receiving, determining the quality and condition of raw potatoes for frying purposes, determining the quality and condition of raw potatoes for frying purposes, etc.
The present book covers complete details of potato cultivation and processing in proper manner. This book is an invaluable resource for agriculture universities, students, technocrats and entrepreneurs.
1. ORIGIN, EVOLUTION, HISTORY AND SPREAD OF POTATO
Introduction, Origin, Archaeological Evidence, Historical Evidence, Evolution, History, Early History, Spread in Europe, Spread in Asia, Africa, etc., Spread in India
2. BACTERIAL DISEASES OF POTATO AND THEIR MANAGEMENT
Bacterial Wilt/Brown Rot, Distribution, Etiology, Diagnostics and Detection, Management, Avoidance, Soft Rot or Black Leg
3. POST HARVEST HANDLING OF POTATO
Significance, Post Harvest Losses, Enhancement of Shelf-Life of Potato Tuber, Avoid Mechanical Tuber Damage Including Internal Bruising, Sorting and Grading of Tubers, Wound Healing and Curing, Weight Loss, Dormancy, Storage Temperature, Treatment of Tubers Against Diseases and Insect, Use of Growth Regulators Against Sprouting, Regulation of Sprouting in Stored Potato, Pre-harvest Application for Sprout Suppression, Post Harvest Application for Sprout Suppressions, Mode of Application, Storage, Controlled And Modified Atmosphere Storage of Potato, Other Storage Methods of Potato, Improvised Country Storage, Low Cost Zero Energy Cool Storage, Kucha Mud House or Room Storage, Pit Storage, Viability of Stored Potato Seed, Gamma-Irradiation, Change in Composition During Storage, Percentage Dry Matter, Carbo-hydrates, Phenolic Compounds, Glycoalkaloids, Vitamins, Processing, Morphological Characters, Chemical Composition, Dry Matter, Reducing Sugar Content, Varieties for Processing, Practical Aspect of Potato Processing, Grading, Cleaning, Peeling, Cutting/Slicing, Blanching/Cooking, Frying, Dehydra-tion, Cooling/Freezing, Sterilization, Packaging, Popular Potato Products, Potato Flakes and Granules, Potato Dice, Potato Chips, French Fries, Canned Potatoes
4. BIOTECHNOLOGY FOR PRODUCTION OF QUALITY PLANTING MATERIAL
Meristem Culture, Thermotherapy, Chemotherapy, Electrotherapy, Virus Detection and Diagnosis, Micropropagation, Micropropagation in Virus-Free Potato Seed Production, Conclusion
5. BREEDING FOR PROCESSING VARIETIES
Potato Products, Quality Requirements for Processing, Morphological, Size and Shape, Defects, Biochemical, Dry Matter, Reducing Sugars, Phenols, Inheritance, Morphological Attributes, Tuber Shape, Growth Cracks, Hollow Heart, Internal Rust Spots, Greening, Biochemical Attributes, Glycoalkaloids, Dry Matter, Reducing Sugars, Enzymic Browning, Development of Varieties for Processing
6. TRUE POTATO SEED TECHNOLOGY
Role of TPS Populations, Potential and Advantages of TPS Technology, Constraints/Shortcomings in the Adoption of TPS Technology, Early History, Priority Areas for TPS Dissemination, Economics of TPS Technology, Agronomy of True Potato Seed (TPS), Utilization of TPS for Potato Production, Substrate Composition and Preparation of Nursery Beds, TPS Sowing, Production of Seedlings for Transplanting, Production of Seedling Tubers, Field Preparation, Crop from Seedling Transplanting, Crop from Seedling Tubers, Crop from Seed Broadcasting, Identification Of Suitable TPS Families, Breeding of TPS Populations, Breeding Requirements for TPS, Parental Lines, Flowering, Production and Fertility of Pollen, Berry/Seed Formation, Production of Hybrid TPS, Planting of Hybridization Block, Hybridization, Harvesting of Berries and Seed Extraction, Processing, Packaging And Storage of TPS, Dormancy in TPS, Evaluation and Selection of TPS Populations, Utilization of TPS for Potato Production, TPS Populations Released, Future Strategies
7. SEED PRODUCTION
Seed Potatoes, Variety, Diseases, Degeneration, Seed Plot Technique, Selection and Preparation of Field, Seed, Thermotherapy, Planting, Seed Size and Spacing, Time of Planting, Fertilization, Irrigation, Weed Control, Roguing and Inspection, Haulm Cutting, Aphid Management, Disease and Pest Management, Harvesting and Storage, Seed Treatment, Impact of the Technique, True Potato Seed (Botanical Seed), Production of Hybrid TPS, Hybridization, Seed Extraction and Storage, Crop Production Through TPS, Nursery, Development of Virus Free Seed of Potato and Testing for Viruses, Selection of Healthy Seed, Sanitation, Meristem TIP Culture, Chemical Treatment, Reduction in Vector Population, Testing of Potato Viruses, Conventional Methods, Advanced Methods, Elisa Test, Advantage of Elisa, Maintenance of Virus Tested Foundations, Potato Biotechnology, Elimination of Pathogen through Meristem Culture, Potato Meristem Culture, Establishment of in Vitro Cultures, From Infected Plants, from Infected Tubers, Steps involved in Potato Meristem Culture, Meristem Tipculture, Micro Propagation of Mericlones:, Micro Tuber Production, Production of Micro Tubers, Production of Normal Tubers, Synthetic (Artificial) Seed, Seed Certification, Methods of Inspection for Certification, Tagging, Content of Breeder Seed Bag, Seed Certification Standards, Quality Control, Objective, Sampling, Procedure of Grow Out Test
8. PHYSIOLOGICAL DISORDERS
Tuber Cracking, Tuber Malformation or Deformities, Surface Abrasions or Feathering, Hollow Heart, Greening, Black Heart, Low Temperature Injury, Sunscalding, Aerial Tubers
9. FAVOURABLE CONDITIONS OF GROWTH FOR POTATO
Climate, Rainfall, Temperature, Light, Soil, Topography, Economical Condition, Capital, Labour
Land Preparation, Preparatory Tillage, Primary Tillage or Ploughing, Country Plough, Mould Board Plough, Bose Plough, Disc Plough, Spade, Tractor, Power Tiller, Secondary Tillage, Ladder or Plank, Harrow, Cultivator, After Tillage, Planting of Potato, Sowing Time, Selection of Seeds, Source of Seed-Tubers for Commercial Use, Seed Stored in Country Cellers, Seed Stored in the Cold Storage, Seed Produced in the Hill Areas, Dormancy of Seed Potatoes, Varieties with Short Dormancy Period, Varieties with Medium Dormancy Period, Varieties with Long Dormancy Period, Breaking of Dormancy, Mechanical Method, Heating of Seed Tubers, Cutting of Seed Tubers, Peeling of Seed Tubers, Chemical Method, Correct Size and Weight of Seed Tubers, Seed Treatment, Seed Rate, Method of Planting, Flat Bed Planting, Planting in Furrows, Planting on Ridges, Pit Method, Spacing, Potato Planting Equipments, Tractor Drawn Fertilizer Drill Cum Line Marker, Tractor Drawn Potato Planter Cum Fertilizer Application, Two Row Space Marker-Cum-Ridger, Potato Planters, Hand Fed Potato Planter, Corrective Type Potato Planter
Manures, Compost, Rural Compost or Village Compost, Urban Compost or Town Compost, Farm Yard Manure (F.Y.M.), Oil Cakes, Edible Oil Cakes, Non-edible
Oil Cake, Green Manure, Fertilizers, Nitrogenous Fertilizers, Phosphatic Fertilizers, Potassic Fertilizers, Role of Nutrients in Potato, Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Sulphur, Zinc, Iron, Manganese, Copper, Micronutrient, Doses of Fertilizers, Method and Time of Application, For the Hills, For the Plains, Autumn Crop, Spring Crop
Early Crop, Main Crop, Method of Harvesting, Animal Drawn Single-row Potato Digger, Two-row-tractor Mounted Potato Digger, Potato Elevator Digger, Potato Spinner Digger, Grading, Marketing, Transport, Storage, Method of Storage, Country Method of Storage, Room Storage, Pit Storage, Heap Storage, Factors Influencing The Storage Behaviour, Variety, Time of Harvest,
Size of Tubers, Cultural Practices, Cold Storage, Physiological Changes During Storage, Periderm Formation, Starch-Sugar Balance, Sprouting, Yield
13. FUNGAL DISEASES AND THEIR MANAGEMENT
Late Blight, Symptoms, Distribution And Losses, Pathogen, Variability, Survivability, Genetics and Cytogenetics, Epidemiology, Sources of Inoculum, Environment and Disease, Disease Spread and Build Up, Management, Chemical, Cultural Practices, Early and Phoma Blight, Symptoms, Distribution, Epidemiology, Management, Cercospora Leaf Spots, Symptoms, Distribution and Crop Losses, Epidemiology, Management, Soil and Tuber Borne Diseases, Black Scurf and Stem Canker, Symptoms, Pathogen, Epidemiology, Management, Powdery Scab, Symptoms, Pathogen, Etiology and Epidemiology, Management, Charcoal Rot, Wart, Minor Diseases, Fungal Wilts, Tuber Rots, Storage Diseases, Dry Rots
14. LOW INPUT TECHNOLOGY FOR POTATO PRODUCTION
Input Intensiveness of Potato Cultivation, Seed, Cultural Operations, Manures and Fertilizers, Weed Management, Towards Low Input Technology for Potato Production, Tillage, Seed, Fertilizers, Irrigation, Weed Control, Pests and Diseases Control, Organic Farming as a Method of Low Input Technology
15. MICRO-NUTRIENT REQUIREMENTS OF POTATO
Effect of Micro-nutrients on Growth and Yield of Potato, Diagnosis of Micro-nutrient Deficiencies in Soils and Plants, Visual Diagnosis, Deficiency Symptoms, Iron, Manganese, Copper, Boron, Molybdenum, Plant Analysis, Soil Analysis, Micro-nutrient Deficiency in Potato Growing Areas, Response of Potato to Micro-Nutrients, Factors Affecting Response of Potato to Micro-nutrients, Root and Shoot Parameters of Cultivars, Micro-nutrients and Quality of Potato Tubers, Amelioration of Micro-nutrient Deficiencies, Methods of Micro-nutrient Application, Time of Application, Sources of Micro-nutrients
16. WEED MANAGEMENT
Methods of Weed Management, Non-Chemical Methods, Crop Rotation, Summer Polughing, Placement of Fertilizers, Mechanical Control, Chemical Methods, Efficient Use of Herbicides, Calibration, Calculation of Herbicides for Application, Integrated Weed Management, Mulching, Effect of Herbicides on Quality of Potato, Dry Matter, Starch, Protein
17. ORGANIC FARMING
Concept, Definition and Components, Value of Organic Amendments and Soil Conditioners, Bulky Organic Manurers, Green Manures, Concentrated Organic Manures, Crop residues, Bio-fertilizers, Vermicompost, Crop and Soil Management, Legume based Crop Rotations, Phytosanitary Crop Rotation, Green Manuring, Agricultural Waste Incorporation in Soil, Agricultural Biopesticides, Sustainable Integrated Nutrient Management, Chemical Fertilizers, Organic Manures, Bio-fertilizers, Green Manuring, Crop Yield and Quality
18. CROPPING SYSTEMS
Sustainable Systems, Potato in Relation to Goals of Sustainable Cropping Systems, Strengths of Potato in Multiple/Inter-Cropping Systems, Potato Based Cropping Systems in Different Agri-zones, North-Western Plains, Western and Central Indo-Gangetic Plains, Eastern Gangetic Plains, Plateau Region, North-Western Hills, North-Eastern Hills, Southern-Hills, Implications and Future Thrusts
19. BIOLOGICAL AND SEROLOGICAL DIAGNOSIS OF POTATO VIRUSES
Chloroplast/Slide Agglutination Test (Sat), Micro-precipitin Test, Agar Double-Diffusion Test, Latex-agglutination Test, Enzyme-linked Immunosorbent Assay (ELISA), das-ELISA, Indirect ELISA, Dot-ELISA (dot Immunobinding ELISA), Tissue Blotting and Tissue Squashes, Immuno Electron Microscopy (IEM)
20. POTATO PESTS AND THEIR MANAGEMENT
Soil Pests, Cutworms, Distribution, Nature of Damage, Population Dynamics and Biology, Management, Cultural and Mechanical, Chemical, Biological, Integrated Management, White Grubs, Management, Minor Soil Pests, Foliage Feeders or Defoliating Pests, Defoliating Caterpillars, Distribution, Nature of Damage, Population Dynamics and Biology, Management,
Epilachna Beetles, Minor Defoliating Pests, Sucking Pest or Sap Feeders, Aphids, Management, Cultural and Mechanical, Leaf hoppers, Broad Mite, Other Minor Sucking Pests or Sap Feeders, Storage Pests, Potato Tuber Moth, Nematode Pests of Potato, Potato Cyst Nematode (PCN), Root Knot Nematode, Cultural Practices
21. POTATO STORAGE
Dormancy, Post-harvest Losses, Physiological Losses, Effect of Temperature, Effect of Relative Humidity, Pathogenic Losses, Storage Methods, Refrigerated Storage, Non-refrigerated Storage of Potatoes, Evaporatively Cooled Potato Store, On-Farm Storage, Sprout Inhibitors, Tetrachloro-Nitrobenzene (TCNB), Maleic Hydrazide (MH), Isopropyl-N-3-Chlorophenyl Carbamate (CIPC), Natural Substances as Sprout inhibitors, Irradiation, Biochemical Changes during Storage, Changes in Carbohydrates, Changes in Nitrogen Fractions, Changes in Enzyme systems, other Biochemical Changes
22. POTATO PROCESSING
History, Areas Suitable for Growing Processing Potatoes, Processing Quality of Indian Potato Varieties, Processed Potato Products, Dehydrated Products - Village Level, Potato chips, French Fries and Flakes - Commercial Production, Grading, Sorting and Washings, Peelingr, Washing, Sorting and Trimming, Chips, French Fries, Flakes, Starch, Other Edible Products, Potato Custard Powder, Soup or Gravy Thickener, Potato Biscuits, Potato Papad, Potato Sticks or Shreds, Chakali, Vada, Alu Bhujiya,
23. STACKABLE POTATO CHIPS TECHNOLOGY
Introduction, Experimental Work, Main Raw Material Characterization, Press Releases, Viscosity Profiles, Dosing Step, Mixing Step, Sheeting Step, Cutting
and Rework Handling, Experimental Work Conclusions, Other Process Steps, Frying and Moulding, Seasoning Device, Portioning and Packaging:
Scientific Name and Introduction, Quality Characteristics and Criteria, Horticultural Maturity Indices, Grades, Sizes and Packaging, Optimum Storage Conditions, Controlled Atmosphere (CA) Conditions, Retail Outlet Display Considerations, Ethylene Production and Sensitivity, Physiological Disorders, Postharvest Pathology, Quarantine Issues, Suitability as Fresh-cut Product, Special Considerations
25. TREATMENT AND DISPOSAL OF POTATO WASTES
Pollution, Terminology, Testing, Regulations, History, Characteristics of Processing Plant Effluents, Components of Potato-Processing Waste, Effect of Process, Design of Effluent Treatment Facilities, Waste Treatment Processes, In-Plant Treatment, Screening (Pretreatment), Primary Treatment, Secondary Treatment. Biological Filters, Anaerobic Systems, Solids Disposal, Advanced Wastewater Treatment, Filtration, Other Treatment Methods, Application in Potato-processing, Municipal Treatment
26. ADVANCED THERMAL APPLICATIONS IN POTATO PROCESSING
Storage, Peeling, Preheating, Blanching, Dryers, Rotary Drum Using Radial Nozzles, Convection Drying, Impingement Roaster, Conveyor Dryers, Spray and Flash Drying, Fryers, Vacuum Frying, Radio Frequency, Freezing Technology, Adsorption Chiller, Waste Treatment, Sanitation, Energy Recovery, Belt Cooker, For Steam-cooking of Potatoes and Roots
27. SNACK CHIP DEEP FAT FRYING
Process Description, Emissions and Controls, Emissions, Controls
28. TROIKA POTATO CHIPS
Business Plan, Summary, The Enterprise, General Information, Contributed Capital, Appraising Market Value of Stockholdersâ€™ Equity, Decision Making,
Profit Sharing, The Product, Analysis of Market and Competition, Marketing and Pricing Strategy, Organization of the Production Process, Risk Factors, Financing and Distribution of Profits, Financial Planning, Appendix, Cultural and Sociological Notes, The Russian Sense of Time, Openness Versus Secrecy, Obedience Versus Autonomy, Attitude toward Law and Contracts, The Importance of Relationships, Organized Crime, Working with Russian Partners
29. MANUFACTURE, STORAGE AND TRANSPORT OF FROZEN FRENCH FRIES
Importance of Frozen Potato Products, Types of Frozen Products, Desirable Characteristics of Processing Potato Varieties, Effects of Crop Production Inputs on Processing Quality, Harvest, Storage, Processing, Frozen Product Storage,
Transportation, Preparation for Final Cooking and Consumption
30. GRADING MANUAL FOR FROZEN FRENCH FRIED POTATOES
For Frozen French Fried Potatoes, Areas of Production, Varieties, Receiving, Determining the Quality and Condition of Raw Potatoes for Frying Purposes, Determining the Quality and Condition of Raw Potatoes for Frying Purposes, Manufacture, Washing, Manufacture, Peeling, Trimming, Slicing, Sizing, By-Products, Desugaring, Blanching, Frying, Fat or Oil, Time and Temperature, Packaging, Inspection During Packing Operations, Inspecting the Product, Sample Unit Size, In Retail Type , In Institutional Type, Fry Color, Fry Color of the Individual Units, Fry Color of the Sample Unit, Fry Color Designation of a Sample Unit, Re-fry Color, Re-fry Color of the Sample Unit, Re-fry Color Designation, Types, Styles, Strips, Length Designations, Determining the Length, Minimum Equipment for Inspecting Frozen French Fried Potatoes, Preparation of Sample, Quality Evaluation, Grade Factors Which are not Scored Flavor, Color Designation of a Sample Unit, Grade A, Good Color, Grade B Reasonably Good Color, Substandard, Uniformity of Size and Symmetry, Grade A, Grade B, Considerations, Defect Tables in the Standards, Assigning the Score for Defects Procedure, Texture, Heating the Product, Oven Method, Deep Fat Method, Sogginess, Hardness, Pull Away, Crisp Outer Surface, Sugary Ends, Excessive Oiliness, Score Points, Scoring Procedure, Certification, Special Instructions, Fry Color Classification, Type, Style, Length Designations, Requests for Specific Certificate Information, Procedure
31. PERFORMANCE ENGINEERED FRYING AND FILTRATION SYSTEMS
SF Series Oil Filter, Consumers Love Coated, Proven Fryers and Filters, Maintaining Cooking Oil Quality, Long-Term Process Productivity, LINK is Comprised of Four Distinct Modules, Productivity Relies on Effective Filtration, An Unlimited Menu of Coated Products, Fryer Heat Method Comparison Analysis, Direct Heat - Direct Fired, Key Advantage, Key Disadvantages Direct Heat- Indirect Fired, Key Advantage, Key Disadvantages
32. COST EFFICIENCIES IN SNACK
Highlights, Sector Overview, Company Description, The Situation, Audit Findings, Humpty Dumptyâ€™s Path to Innovation and Profitability, 2nd Stage R&D Study, Implementation Status, Drivers for Change, Implications to the Food Sector, Food Industry Cost Reduction Program, Ontario Ministry of Agriculture and Food (OMAF)
33. LATEST RADIX POTATO FLAKE SORTER
INSTALLATION EXCEEDS EXPECTATIONâ€
34. T H E R M A L P R O C E S S I N G S Y S T E M S F O R P O T A T O E S
The Experience You Need, The Excellence You Deserve, Satisfying Customer Performance and Profit Objectives, Testing and Research, Computer Aided Design and Manufacturing, Turnkey Installation, A World Renowned Service Organization, Choose From these Accessories & Options to Customize Your National Installation, Apron Cleaning Devices. Feed/Discharge Equipment, Other Options, National Offers a Complete Line of Thermal Processing Equipment to Meet the Needs of the Potato Industry, Conveyor Preheater, Two-Stage/ Tri-Mode Belt Blancher, Bi-Mode Dextrose System, Conveyor Dryers & Equilibration Systems, The Seal-Welded Modular Dryer(SWMD)
35. THE POTATO SYSTEM IN WEST JAVA, INDONESIA
Abstract, Acknowledgments, The Potato System
In West Java, Indonesia, Introduction, General Considerations, Methods and Procedures, Potato Production, Present Situation and Trend in production, Cultural Practices, Cost and Benefit, and Institutional Aspects, Conclusions and Issues for Further Research, Potato Marketing, General marketing Situation and Trend in Price of Potatoes, Marketing of Ware Potato, Potato Seed, and Processing Potato, Ware Potato Marketing, Sorting and Grading, Marketing Channels, Field Petty Assembly Traders, Contract traders, Rural Assembly Traders, Regional/Inter-Regional Traders, Wholesalers, Retailers, Marketing Margins, Potato Seed Marketing, Marketing Channels and Marketing Margins for Potato Seed, Marketing of Potatoes as Raw Material for Chips, Conclusions, Potato Processing, Large-Scale Potato Chips Processing, Small-Scale Potato Chips Processing, Conclusions, Consumer Preferences for Potato Chips, Consumer Preferences by Income Group: Results of a Household Survey, Panel Survey of Acceptance of Several Potato Chip Products, Conclusions, Conclusions and Recommendations
36. SCREW BLANCHER FOR POTATO PROCESSING
The equipment, The advantages, Technical Data Screw Blancher
37. PREWASHER WITH CYCLONE DESTONER
FOR POTATO PROCESSING
The Process, The equipment, The advantages, Technical Data, Prewasher
38. BATCH FRYER
Automatically Produce Consistently Uniform Kettle Style Potato Chips, Up to 360 lbs/hr or More, Superior Oil quality, Oil Level Control, Ready to Run, Automatic Slice Stirring, Full PLC control, Easy Cleaning, Optional Features
39. BOOSTER HEATER
Utilize Wasted Exhaust Heat, Boost Output & Save Fuel, Uniform Heat Transfer, Self-Cleaning Tubing, Multi-Layer Insulation, Rugged Construction, Booster Heater Model BH
HISTORY and Spread of Potato
rightly called the
vegetable that changed history provided both the spark and the fuel for
centuries to the social change. While conquering the world it was
lauded cursed and praised feared and loved until humanity welcomed it
home and hearth. Today as one of the world s major non cereal food crop
is grown in more than 148 countries in a wide variety of soils and
surpassed only by wheat rice and maize in total production. Yet till 16
century it was unknown to the people of Europe Asia Africa and North
The crop has a fascinating history of its origin evolution and spread
world stretching to nearly 7000 to 9000 years back. Some of it is well
documented while other has been chronicled from the archaeological
the South America where it grows wild in nature present the widest
forms in tuber shape size colour taste etc. indicating its origin in
American continent. The main cultivated potato species Solanum
tuberosum L. a
tetraploid (2n=4x=48) is believed to have originated from Andes of Peru
Bolivia in South America more specifically in the basin of lake
Titicaca on Peru
Bolivian borders from its wild diploid ancestors many of which may be
now. Two main centres of diversity of tuber bearing Solanum species are
America and Andean region of north western Argentina. Peru and southern
Bolivia. The species grow in a wide variety of habitats from semi
conditions of northern Argentina southern Bolivia and Mexico to the
rainfall subtropical forests of Central and South America. Thus potato
wide adaptation to altitudes right from the sea level to nearly 5000
beautiful ceramics were excavated dating from the Moche cultures in
Peru (c. AD 1 600) and the Chimu peoples (c. AD 900 1450) as well as.
Pacheco urns from the Nazca valley in southern Peru (c. AD 650 700).
ceramics depicting many forms of potatoes were from coastal areas.
is presumed that the potters obtained potatoes by barter or other means
farmers in the highlands where potatoes were actually cultivated .
these ceramics are restricted to Peru and none was recovered from
Ecuador Bolivia Argentina or Chile even though the potato is certain to
been an ancient crop in these countries also. Actual remains of the
were also recovered infrequently from tombs dwellings and rubbish heaps
including chuno or tunta from some archaeological sites. Archaeological
of potatoes from the Chilca valley near Lima have been radiocarbon
7000 years before present. There is much later evidence from rubbish
and food stores of potato cultivation at 4500 to 3500 years before
valley evidence based on excavations in Mexico and elsewhere takes the
of potato cultivation back to an age when maize first became cultivated
Mexico and places it with the approximate time of agricultural origin
New World. From studies between these old potatoes and the distribution
existing primitive cultivated potatoes and the wild species most
them it seems highly probable that the first ever potatoes were
the northern Bolivian region of Lake Titicaca/Lake Poopo.
Peru Francisco Pizarro may well have been the first European to see
1533 but there is no actual (historical) record of this event. The
historical record is of 1537 when a band of Spaniards led by Jimenez de
penetrated into the highlands of what is now Colombia. This was
accounts of Lopez de Gomara for potatoes in southern Peru and by Pedro
Leon in the area of what is now southern Colombia and northern Ecuador.
Potatoes in Chile received first mention by Sir Francis Drake in 1578.
of the potato also indicate its ancient and widespread cultivation
differ completely from the main Red Indian languages that were spoken
areas where the potato was first growing. Thus in the Chibcha language
Central Colombia the names iomza iomuy etc. were used in Quechua the
of the Inca Empire the usual name was papa. In Bolivia the Aymara
the words amka and choque whilst in Chile the Araucanians gave it the
poni. The Spaniards adopted the name papa for the potato which was used
throughout their South American colonies. In Europe neither batata nor
potato was ever adopted because the Spaniards first encountered sweet
not having a name for a similar tuber they used the Indian word batata.
Subsequently other tuberous plants that they found in their American
were given the same name. Potata and potato are clearly cognate forms
consequently the word papa which is still in vogue in whole of the
Latin America never spread outside this area even though the plant
now grown in most parts of the world. We can say with some certainty
historical evidence clearly corroborates archaeological evidence about
origin of the cultivated potato from the Andes of South America.
occur only in the Americas. They seem to have evolved by means of
and ecological isolation rather than by genetic incompatibility. The
regarding the evolutionary relationships of various species is not very
However the cultivated species were at one time confined to the Andes
America and the lowlands of southern Chile in both cases being adapted
cool temperate climates of these regions. The related wild species are
more widespread. There are seven cultivated tuber bearing Solanum
S. stenotomum S. ajanhuiri S. phureja S. chaucha S. juzepezukii. S.
ssp. andigena S. tuberosum ssp. tuberosum and S. curtilobum occurring
polyploid series with a basic chromosome number of 12 and ranging from
to pentaploid. Several of them are fairly similar to each other and for
reason were classified by Dodds as groups of S. tuberosum rather than
species. Their probable evolutionary relationships are shown in Fig. 1.
S. Stenotomum is grown from central Peru to central Bolivia and is
be the most primitive probably having been derived from the diploid
species S. leptophyes or possibly S. canasense both of which still
occur in the
central part of its distribution area. At least four wild potato
widely believed to be involved in the process of evolution. Evidence
that hybridization of S. stenotomum with the weedy species S.
subsequent chromo some doubling produced the tetraploid S. tuberosum
andigena in the central Andes. Some workers however consider that the
tetraploid Andean potatoes are derived from S. stenotomum by simple
doubling. This tetraploid sub species was carried by ancient people
southern Chile where it became adapted to the long day length to evolve
subsp. tuberosum. A similar process in Europe caused the same
take place under the long day conditions. However it may also be stated
certain authors believe that subsp. tuberosum from Chile and Europe
subsp. andigena by certain cytoplasmic factors that it may have
some wild diploid species such as S. chacoense.
days the cultivated diploid species S. phureja evolved from S.
through a process of artificial selection by Andean farmers in lower
eastern valleys and acquired shorter dormancy so that three crops could
grown in a year.
hybridization of 5 stenotomum with the wild frost resistant species S.
megistacrolobum gave rise to the diploid S. ajanhuiri. The F hybrid
the Yari group of varieties and a probable back cross to the cultivated
gave rise to the Ajawiri group of varieties. Similarly the F cross from
series of hybridizations between S. stenotomum and the wild tetraploid
S. acaule gave rise to a highly sterile triploid S. juzepczukii which
incorporated the strong frost resistance of S. acaule. A further
between S. juzepczukii and S. tuberosum subsp. andigena produced the
slightly less frost resistant pentaploid species S. curtilobum. This
involved a 2n gamete from S. juzepczukii and a normal gamete from S.
subsp. andigena. A series of crosses between S. stenotomum and subsp.
have given rise to the triploid hybrids named S. chaucha.
network of cultivated species or species groups which evolved chiefly
central Andes of Peru and Bolivia involving four original wild species
acaule. S. sparsipilum S. leptophyes and S. megistacrolobum. All but
these cultivated potatoes have always been confined to that central
However the diploid S. phureja has extended northwards into Ecuador
and Venezuela whilst the tetraploid S. tuberosum spread into southern
potato was the most productive source of main food for centuries for
in the high Andes and southern Chile. Potatoes were dried by Andean
make chuno for use during food shortage between successive crops caused
frost or other unfavourable growing conditions. Chuno is a freeze dried
powder of the bitter frost resistant potatoes grown at 3 600 to 4 400
process requires a dry climate with high day and very low night
allowing freeze drying of potatoes for several nights followed by
washing for many days in running water. The long lasting chuno is
prepared by thorough trampling of such potatoes by men and women folks
sqeeze water out of them and finally dehydrating them in hot sunny days
freezing nights for many days. Still an important food in the highlands
chuno has been aptly extolled for its virtues in an ancient Incan adage
Stew without chuno
is like life without love .
conquerors found potato being very widely cultivated in what are now
Peru and Bolivia and the Araucanian region of Chile. Following the
Peru the Spaniards introduced potatoes in Spain and further spread it
European countries including Italy Belgium Germany France Switzerland
Holland by the end of the 16th century. Initially potato was grown only
curiosity in the Europe s botanical gardens and remained a shunned
best food for swine and country bumpkins2 for next two centuries. It
wrath for causing war and lust to tuberculosis rickets syphilis and
it fell victim to its lineage being member of Solanaceae and having
hallucinogenic and narcotic cousins as mandrake and deadly nightshade
belladonna) containing scopolamine and atropine like poisonous
in ointments said to give witches the power to fly. Potatoes were
unworthy of human consumption by the Scottish clergymen as they were
mentioned in the Bible. Possibly the word spud (present day English
potato) got its name being acronym for the Society for the Prevention
Unwholesome Diet a 19th century activist group dedicated to keeping the
of Britain. The first edition of the Encyclopedia Britannica referred
potato as a demoralizing esculent esculent being an ostentatious word
Russians referred it as Devil s apples while in France potatoes were
be fit only for animals and poor people. The potato s struggle for
in Europe took place at every level from Kings Kitchens to slum street
the hallowed halls of parliaments to the battlefields of Seven Years
Resistance to eating potatoes was so strong in parts of the continent
willing rulers virtually had to force potatoes down their subjects
1651 Frederick William of Prussia even issued an edict to cut off the
ears of any one refusing to plant potatoes. Frederick the Great still
resistance more than a century later sent a wagonload of tubers to
a famine stricken area only to receive a petulant reply. The things
neither smell nor taste nor even the dogs will eat them so what use
they are to
us? forcing the great leader to hold an open air banquet where potatoes
served to prove that they are not only edible but also fit for royalty.
potato enthusiast Antoine Auguste Parmentier even had to trick peasants
stealing tubers from Louis XVI s Royal Gardens to convince them of the
remained a botanical curiosity till about the mid 18th century and was
grown in any western European country except Ireland where potatoes
most profitable new crop mainly for human consumption and for pigs
well on potatoes. In Ireland the situation was very different where in
century religious differences were cause for the feuds and unrest
Norman Irish aristocracy and the English people. The common people
and devoted to peaceful agriculture for livelihood were the chief
when their cattle were driven off or slaughtered by one side or the
their land and crops ravaged either by the Irish or English. During
the miserable peasantry on the brink of starvation was driven to rely
more on the potato as source of food. However when cattle food stores
standing crops were used or destroyed potatoes being underground
destruction. People realized this and did not harvest and store
dug them up as and when required with sufficiently leftover to serve as
the next crop. Thus the potato became the chief food of the people. In
recorded that a barrel of potatoes containing 127 kg would last an
of six persons for 6 days indicating on an average consumption of over
per person per day.
18 h century none seems to have been aware of the danger to the economy
nation dependent on a single crop. The warnings of Wakefield and by
unheeded till August 1845 when suddenly one warm rainy day in August an
malady (late blight) struck the Irish potato fields.
rotted in the fields sending an unbearable stench across the
repeating the same scene across whole of Europe. This was also true in
and 1848 resulting in famous famine and death of nearly 2.5 million and
migration of one million Irish including the famous Kennedys and
One of the
during the Hundred Years War in Europe was christened Kartoffel Krieg
potato war between the Prussians and the Austrians acquiring its name
contending armies ate up all the potatoes along the battle lines in
then called off the fighting.
of Potato and their Management
The potato crop is prone to
many diseases caused by
pathogenic fungi viruses mycoplasmas and bacteria. Bacterial diseases
on potato are 1) bacterial wilt Ralstonia solanacearum 2) soft rot of
tuber 3) common scab 4) pink eye and 5) ring rot sepedonicus Devis et
India ring rot and pink eye do not occur. The leaf spot is a minor
Therefore the following chapter pertains to only two economically
bacterial diseases i.e. bacterial wilt and soft rot.
BACTERIAL WILT/BROWN ROT
wilt/brown rot is the most destructive bacterial disease of potato.
potato the pathogen Ralstonia solanacearum (formerly Pseudomonas
more recently Burkholderia solanacearum) also causes lethal vascular
diseases in more than 200 plant species belonging to at least 50
plant families including several crops like potato tomato chilli
ginger and others. In India alone more than 130 plant species belonging
genera have been reported to be infected by this pathogen. It is the
bacterial disease recorded in India from Pune district of Maharashtra
In different countries it is known by different local names such as
wilt brown rot Granville wilt ring disease slime disease southern
wilt etc. In India it is widely known as ghera and uktha bangle blight
or paryya. The disease has a history of changing cropping pattern in
of the world. Potato cultivation was abandoned in Ranchi district of
to severe bacterial wilt infestation forcing the farmers to shift to
cultivation of other crops. The disease is unpredictable as evidenced
outbreaks of bacterial wilt of potato in Europe. Resistance against
wilt in potato is scarce and thermo sensitive in nature. Therefore it
apprehended that the disease might become more problematic particularly
event of changes in cultivated varieties and global warming.
wide spread in tropical sub tropical and warm temperate regions and has
reported from six of the seven continents. It is endemic in South Asian
Asian Southeast Asian and even in some central Asian countries. It is
distributed throughout the Indian sub continent including India
Pakistan Nepal and
Bangladesh. In India R. solanacearum is prevalent in all the states
Punjab Haryana western part of Uttar Pradesh and Andhra Pradesh. The
distribution of this pathogen is a reflection of its evolutionary
is correlated with the extent of genetic diversity within a species. In
bacterium is notorious for its phenotypic diversity in respect to
morphology races and biovars disease symptoms and host range. Modern
of molecular genetic analysis suggest that this bacterium probably
from a common ancestor possibly at a single location near the equator.
evolution of the bacterium then occurred with several wild hosts
forest eco systems in geographically isolated areas creating plenty of
diversity within this species.
and economic losses vary from place to place season to season and the
crop damaged. Crop loss up to a maximum of 75% has been reported in
the disease was first established by Erwin Frink Smith in 1896 and the
bacterial entity was christened as Bacillus solanacearum nov. sp. and
Pseudomonas solanacearum. The bacterium belongs to beta subclass of the
Proteobacteria. With the introduction of molecular techniques generic
nomenclature of the wilt pathogen underwent rapid change from
Burkholdena to Ralstonia. Yabuuchi et al. 1992 proposed the new genus
Burkholderia to accommodate RNA homology group II including Pseudomonas
solanacearum with P. cepacia as type species. Later work based on 16S
genes and polyphasic taxonomy showed dichotomy in genus Burkholderia
new genus Ralstonia was proposed with R. picketti as type species.
is a Gram negative rod measuring approximately 0.5 0.7 x 1.5 2.5 mm.
isolates are mainly non flagellated non motile and are surrounded by
extracellular slime. Avirulent isolates are devoid of any extracellular
bear 1 4 polar flagella and are highly motile. Polar fimbrae are
are associated with twitching motility and spreading growth on solid
Cells contain inclusion of poly (b hydroxybutyrate which are
refractile under phase microscope and commonly show bipolar staining.
It is a
chemoorganotroph with aerobic respiratory metabolism catalase and Kovac
oxidase positive the optimum temperature for growth varies from 27 37°C
depending on the strain and nitrate is reduced to nitrite. R.
usually shows low level of salt tolerance growth is often inhibited by
1.7% NaCI. The bacterium lacks fluorescence phenazine and carotenoid
A brown to black diffusive pigment is often produced on variety of agar
range physiology serology membrane protein pattern numerical taxonomy
bacteriophage susceptibility of the bacterium established highly hetero
composition of this species. However from a pathologist s point of view
solanacearum has been delineated into five races on the basis of host
(Table 1) and five biovars on the basis of ability to use disaccharides
hexose alcohols (Table 2). Recent studies established existence of two
RFLP divisions having only 13.5 percent similarity. In future creation
RFLP groups can not be ruled out. Marked differences in geographical
distribution of races and biovars is observed. Race I/biovar III and IV
predominant in Asia. Race 3 biovar II is restricted to cooler region of
world including tropical highlands.
Diagnostics and detection
be best diagnosed by observing symptoms. Expression of the disease may
partial collapse of foliage followed by recovery and subsequent
(Fig. 1). Tubers largely do not show any external symptoms but Figure
plant showing bacterial wilt symptoms transversely cut tubers from
plants show vascular browning and in exceptional cases tubers might
slimy depositions at eyes (Fig 2). Water soaked lesions on tubers
have also been reported. Incipient infection of tubers Figure 2.
showing bacterial ooze in vascular bundlecan be accentuated by
at 30°C for six weeks and then tested for exudation of bacterial ooze
tuber eyes. This test is advocated by the International Potato Center
Peru. Potassium hydroxide (KOH) test is useful to differentiate R.
infection from C. michiganensis ssp. sepedonicus. Precise diagnosis may
sufficient to take up suitable remedial steps. However in many cases it
to be followed by sensitive detection. Detection of the pathogen can be
undertaken based upon the purpose need time and the cost. This involves
isolation and culturing on SMSA medium followed by metabolic profiling
system) and proving the Koch s postulates (host test) using
(ELISA Immunofluorescence) and confirming through molecular methods
Acid Hybridization). Isolation of the pathogen in pure form can be
adopting molecular detection techniques. Each of the above detection
has specific advantages and disadvantages in respect of specificity
time and cost. Each technique has a threshold level of bacterial
that can be detected
Sensitivity of the different techniques used for detection of R.
from potato Method Detection level Remarks (cells/ml)
Handling of Potato
unawareness about post
harvest handling practices accounts for about 10 15% wastage of tubers.
10 per cent of the total production is used as seed tubers. There is a
gap between the existing storage facilities and the actual requirement
in the country. At present the cold storage capacity in the country is
10.3 million tonnes whereas the production of tubers is around 18
tonnes. The post harvest losses can be minimized by generating
techniques of tuber handling and storage. Public agencies and research
organizations are engaged in reducing some of the problems associated
harvest handling of potatoes.
production in India has been increasing steadily during the last fifty
and the total production was 18 million tonnes in 1997 98. During the
over production we are unable to store or utilize the surplus potatoes
available in the country. Consequently we witness gluts at regular
which mean economic loss to the grower and wastage of precious food.
the importance of storage and processing for better post harvest
potatoes attempts were made at CPRI to study and understand the
potato storage during the hot humid summer months and the problems
potato processing in India.
improvement such as fast and cheap transportation storage and
help to make potato production more profitable for farmers by improving
to markets raising local value addition and promoting greater
middlemen. The perishable nature of potatoes combined with the
expensive refrigerated storage facilities and their uneven distribution
in transportation the adverse environmental conditions prevailing
main storage and lack of significant processing of potatoes create
around harvest time.
POST HARVEST LOSSES
techniques during post harvest handling and storage should be used so
losses due to physical causes like damage during digging transport to
etc. and physico chemical changes like conversion of starch into
sugars shrinkage and weight loss due to transpiration and respiration
tubers due to infection by micro organism etc. could be minimized. Post
losses result partly from insect damage and physical injuries like
spades during harvest. Khatana et al. reported 6% wastage in the field
wastage may vary from 2 25% depending on the weather which governs
black heart and low tempera ture injury are also a result of mal
practices. It renders tubers inconsumable thus causing great loss to
ENHANCEMENT OF SHELF LIFE OF POTATO TUBER
Mechanical Tuber Damage
Including Internal Bruising
be controlled by reducing external forces imposed on the tubers during
and at various stages of handling by proper design and use of
lifting and handling techniques. When the potato tubers get matured
removed by digging with the help of spade or kudali due to which
caused and skin is damaged. Splitting of tubers can be avoided by
during these operations. In prolonged storage internal bruising is
the pressure spots developed inside the tubers. The drizzling of rains
during digging make the harvested tubers more susceptible to rot by
like Pythium Phytopthora and Erwinia species. In the plains late
potato where temperature rises 25°C the injury get prone to cause
soft rot and charcoal rot (Macrophomina phaseolina).
and Grading of Tubers
necessary to remove diseased and damaged tubers. The storability is
related to size of the tubers so grading is essential. The tubers
than 75g may be graded in to table purpose category. However the small
tubers about 13 31 mm diameter are preferred for seed purposes which
be kept under country storage. Seed tubers below 25 mm size are
under size and more than 65 mm as over size. Suitability for processing
potato tubers is decided according to its shape size and depth of eyes
chemical constituents like tuber dry matter and reducing sugar content.
to round oval potatoes are used for the preparation of chips while
tubers are used for canning large grade tubers (40 60 mm. diameter) are
preferred for chipping and for preparation of French fries.
Healing and Curing
potato tubers has an important bearing on storage losses. Potatoes have
relatively tender skin at harvest and some damage occurs invariably
not properly healed soon after harvest can result in excessive
rotting during storage. Wound healing involves deposition of suberin.
healing is faster at higher storage temperatures. The process is slowed
low temperature increased CO2 concentration or
by sprouts inhibitors
used at the time of storage. Wound heating at 18°C is faster and it
15 days whereas about 30 days are required at 12°C and at 10°C it is
nil. For the formation of wound periderm initially the cells at the cut
become suberized followed by the development of meristematic layer
phallogen or cork cambium a few layers below the cut surface. The cut
layers towards the out side by division in the phallogen become
cells making the periderm a barrier for evapouration to water and entry
healing and curing potatoes after harvest are quickly dried kept
heaps in the field or under the shade of trees or in sheds undisturbed
time. Heaps are covered with straw to protect them against frost and
heaps may be 1 1.5 m high and 3.35 m wide at the base. Period of 10 15
sufficient for proper curing.
the effect of temperature and gamma irradiation on wound healing in the
Kufri Chandramukhi and concluded that the major cause for the bacterial
rot in tubers when they are stored under high tropical ambient
when irradiated for sprout inhibition is the impairment of wound
of starch and moisture loss through evaporation. Harvested potato
living organisms who breathe in oxygen and give out carbon dioxide
heat as waste products from the organic process. This process is at the
of stored starch in potato. The higher the temperature of the potato
greater the loss of starch and the potatoes age. Starch loss is
10% of the total weight loss of healthy potatoes after storage. Damaged
potatoes age more rapidly and loss moisture. Stored potatoes lose
due to two physiological processes transpiration and respiration which
reduced by increasing the relative humidity and reducing the
storage atmosphere respectively. These losses are generally low as long
potatoes remain dormant. When dormancy is over there is an increase in
losses due to sprout growth. Higher weight loss is caused under the non
was found to be the major source of weight loss during storage (18 30°C
90%) for a period of 4 months. Contribution of respiratory carbon loss
weight loss was slight (3.96 6.07 %) Respiration rate measurement with
red gas analyser showed higher rate of weight loss in sprouting tubers
compared to dormant one s while Mehta and Kaul reported that there was
correlation between respiration rate and weight loss during storage up
harvested potato tubers are placed under environmental conditions
for sprout growth sprouting does not normally occur. The time of onset
sprouting is determined by the length of the dormant period of the
dormancy may be considered as an important component of good keeping
However storage trials conducted at Patna showed that the long dormant
Kufri Sindhuri suffered maximum rotting and therefore it is not
a long dormant variety should have a good keeping quality. An
between short tuber dormancy and earliness has been reported by Kaul
Since weight loss and rotting tend to be higher in sprouted than in
tubers therefore long dormancy may be considered as an important
of storage is an important factor that determines the break of dormancy
onset of sprouting. Storage trials carried out at Patna on various
storage structures in decreasing order of temperature. Ordinary kutcha
double walled insulated store (27 30°C). An underground cellar and a
cooling room of a cold store (16 18°C) indicated that high storage
tend to retard sprouting. In the case of loose stored potatoes the
in temperature between the potatoes at the bottom and the potatoes at
must not exceed 0.8°C. Greater differences in temperature may give rise
condensation and germination in the potatoes at the top.
of Tubers Against
Diseases and Insect
may carry various types of disease inoculums and nematodes. For
the tubers the fungicides (bavistin and benlate etc.) antibiotics
(Streptocycline tetracycline etc.) and insecticides which are safer
used. Nagaich and Upreti eradicated the leafroll and yellow diseases by
tubers in hot air at 40°C for two hours daily for 6 weeks. Chemicals
(1.75%) (Dutta and Thaplyal 1978) and boric acid 10% have been reported
effective in control of black scurf and scabs. These diseases can also
controlled by treating seed tubers with organomercurial compounds.
of Growth Regulators
living entities as they respire. The respiration rate is influenced by
temperature and O2/CO2 ratio. It regulates the process of sprouting.
respiration of potato causes breakdown of starch into simple sugars
supplies food material to buds during sprouting. Energy and simple
encourage cell division of buds.
regulators synthesised during respiration are involved in the process
sprouting. The relevance of GA Auxin and ABA during sprouting has been
by various workers. Hemberge reported that the extract from dormant
inhibited the coleoptile and inhibition activities remained higher
dormancy in treated coleoptile and decreased prior to sprouting. The
was named as P inhibitor by Bennet Clark and Kefford. Later on
which was recognised as active component of the beta complex inhibitors
been isolated from potato tubers and confirmed its involvement in
sprouts. The mode of action of endogenous GA other growth promoters and
Abscissic acid in regulation of sprouts is well established fact where
activates the buds while ABA was found associated with dormancy of
Finally Burton confirmed the involvement of ABA. The level of
increases during termination of dormancy however various experiments
that not only ABA GA mechanism is associated with regulation of
other chemicals are also taking part in this phenomena.
of Sprouting in
sprouting in the storage should be emphasized to maintain the tuber
to prolong the shelf life of ware tubers. The spray of various growth
inhibitors like MENA 2 4 5 T Maleic hydrazide and CIPC etc. are useful
sprout suppression in storage.
Harvest Application for
(MH) has been found effective as sprout suppressant for table potatoes.
foliar spray of MH at the rate of 3000 ppm (approx 2 lit a.i./ha)
effective during storage.
2000 to 3000 ppm (2 3 g/lit of water) at 2 3 weeks before harvesting
reported to be effective in controlling the sprouting in storage at
At IARI New Delhi however it has been observed that the translocation
of MH was
not uniform to all the tubers and as a result only about 15% of the
positive effect on sprout control. MH is the chemical sprout
registered for use in India. Trials were carried out with a liquid
containing diethonalamine salt of MH at Jalandhar Shillong Patna and
Ootakamund. One spray of 0.3% MH equivalent 2 3 weeks before harvesting
reduce the yield significantly and resulted in no significant changes
contents of starch reducing sugar s or soluble proteins. The sprout
significantly suppressed by MH treatment. The content of MH residues in
tubers was within the permissible limits (30 60 ppm). Hence MH is a
sprout suppressant for ware potatoes.
Production of Quality Planting Material
approaches are now routinely used to obtain pathogen free planting
potato. Meristem culture was perhaps the first biotechnological
employed to produce virus free potato clones. The technique in
accurate and sensitive virus detection procedures has been highly
over the years in elimination of major viruses from systemically
potato clones. Methods have also been developed for mass multiplication
virus free mericlones using micro propagation. Virus free in vitro
produced are either planted directly in the field for raising
or used for the production of microtubers in the laboratory or
greenhouses. These techniques have been successfully integrated in
production programmes in many countries.
and virus like agents infect potato (Solanum tuberosum L.) plants.
viruses are systemic pathogens and therefore perpetuate through seed
Thus the losses caused by viral diseases are not only confined to the
infection occurs but continue as long as the diseased tubers are used
While plants infected with bacteria and fungi respond to treatments
bactericidal and fungicidal compounds there is no commercially
treatment to protect virus infected plants. Being dependent on host for
replication and protein synthesis selective interference of viral
multiplication by chemical means without adversely affecting the plant
acid and protein synthesis is almost impossible.
culture denotes in vitro culture of meristematic dome of actively
cells located at the extreme growing tip of the shoot along with a
the subjacent tissue containing one or two leaf primordia (Fig. 1).
of tissue is about 0.1 0.3 mm in size. In the absence of chemical
viral diseases meristem culture is the only available method to
viruses from systemically infected potato cultivars. This technique is
the fact that in rapidly growing meristematic tips viruses are either
their concentration is very low. Despite the phenomenal success of
culture in elimination of plant viruses it remains still unclear as to
apical/axillary meristems contain a little or no virus? There are
spread through vascular system but the vascular system is not developed
replication during mitosis and high auxin content in the meristem may
virus multiplication through interference with viral nucleic acid
virus inactivating systems with greater activity in the apical region
hypotheses have never been proved unequivocally.
size of the explant meristem location and cultural factors largely
success of virus elimination by meristem culture. In general larger the
the meristem better the chances of its survival in vitro whereas
size of the meristem better the chances of its being virus free. As the
distribution of a virus within a plant is uneven especially towards the
tips meristem of varying sizes are used to regenerate virus free plants
depending on the genotype and virus strain under consideration. It is
to excise apical meristems from terminal buds because they have more
rudimentary leaves and leaf primordia than the axillary buds. There is
difference between the apical (axillary meristems and in terms of
freedom from virus infection. Therefore axillary meristems are
apical meristems in many laboratories for virus elimination.
possible to eliminate viruses from potato plants following meristem
alone plant regeneration from meristems takes four to eight months and
sometimes depending on the nature of the virus the percentage of virus
obtained from regenerated meristems is low. As a result meristem
procedure is often combined with thermotherapy and/or chemotherapy to
the likelihood of obtaining virus free plants.
plants at higher temperatures significantly reduces replication of many
viruses by disrupting viral ssRNA and dsRNA synthesis. Higher
37°C) cause disruption in the production and/or activity of virus
movement proteins (MPs) and coat proteins (CPs). MPs are involved in
cell movement of viruses through plamodesmata and plant vascular system
CPs play a role in the reconstitution of virus particles from
nucleic acids. Therefore thermotherapy of infected plants followed by
culture improves virus freedom even from relatively large size
Reduction in virus titer is higher if the infected plants are exposed
elevated temperature for longer periods. Current virus elimination
involve either growing of whole plants or in vitro cultures at
close to the threshold of normal plant growth. The exact temperature
of treatment vary with the virus and the heat tolerance of the host
combined with thermotherapy is widely used for virus elimination in
source plants infected with viruses are incubated in a growth chamber
light intensity of 30 50m mol m s at 35 37°C for 2 6 weeks. After
periods of thermotherapy the meristems are excised and cultured on
medium for regeneration.
followed by apical meristem culture has also been shown to successfully
eliminate several viruses from infected plants. Viroids some of which
resistant to elevated temperatures have been effectively eliminated by
therapy. Low temperature therapy (4 7°C) followed by meristem excision
regeneration has been used to eliminate potato spindle tuber viroid
from infected potato plants.
involves the use of chemicals like antibiotics plant growth regulators
acids purine and pyrimidine analogues to inactivate viruses or inhibit
replication/movement of viruses in tissues. These chemicals can either
sprayed on growing plants prior to excision of meristems or
tissue culture media. As early as in 1954 eradication of PVX from
cultures by malachite green and thiouracil treatments was reported. Of
chemicals tested for plant virus elimination synthetic nucleotide
like ribavirin (Virazole 1 D ribofuranosyl 1 2 4 triazole 3
DHT (5 dihydroazauracil) have been particularly effective in inhibiting
different plant viruses. In vitro chemotherapy of meristematic explants
antiviral chemical ribavirin has been found to be most promising for
elimination of major potato viruses. Though the exact mode of action of
ribavirin on plant viruses is not understood following possibilities
triphosphate a major
derivative of ribavirin inhibits viral RNA polymerase synthesis.
5 phosphate a
derivative of ribavirin inhibits IMP dehydrogenase and thereby
GTP pool and nucleic acid synthesis.
interferes with capping
at the 5 end of viral mRNA leading to inefficient translation.
chemicals such as 8 azaguanine 5 fluorouracil 2 thiouracil and Para
fluorophenylalanine have also been tested for virus elimination in
concentrations of many antiviral chemicals required during chemotherapy
inhibit virus multiplication are very close to the toxic concentration
host plant. In addition there is always a possibility of mutations when
plants are exposed to antiviral chemical. Therefore in vitro ribavirin
at low concentrations combined with thermo therapy has been used to
viruses from infected potato cultivars. In such cases simply culturing
shoot cuttings can eliminate some viruses like PVY/A and PLRV in potato.
of explants of infected potato plants has recently been reported to be
effective means for virus elimination. Potato stems infected with PVX
exposed to 5 10 or 15 mA for 5 10 minutes followed by immediate
the shoot tips in vitro. The highest efficiency was obtained at 15 mA
for 5 min
and about 60 100% of the regenerated plantlets tested negative against
Electrotherapy technique is yet to be tested against other potato
VIRUS DETECTION AND DIAGNOSIS
taking all precautions to excise small meristem tips and subjecting
various treatments favouring virus elimination ultimately very few
mericlones are obtained. Therefore meristem derived plants must be
virus freedom before using them as mother plants in micro propagation.
sensitive and rapid detection of potato viruses is critical for
virus free mother plants and their integration into seed production
wide array of serological and nucleic acid based assays is available
accurate detection and diagnosis of potato viruses.
immunosorbent assay (ELISA) dot immunobinding assay (DIBA) and
electron microscopy (ISEM) are most widely used methods for detection
viruses. Serological assays involve trapping virus particles on a
surface to which a specific antiserum has been attached. An ELISA in a
microtitre plate or dot blots on a nitrocellulose membrane are used to
a colour reaction dependent on the virus concentration. In ISEM the
negatively stained viruses are viewed under the electron microscope.
used when an available antiserum contains non specific antigens that
ELISA specificity. Protein A complemented immune electron microscopy
(PAC IEM) a
modification of ISEM makes use of protein A s high affinity for IgG to
trapping and minimize non specific trapping of virus particles. Over
various modifications have been introduced in ELISA systems with
availability of monoclonal and polyclonal antibodies to reduce host
hybridization is based on specific pairing between the single standard
RNA and a complementary nucleic acid probe to form double stranded
acid. Thus either DNA or RNA sequences may be used as probes for
plant viruses. Hybridizations are usually carried out on solid support
(nitrocellulose or charged nylon) where the target nucleic acids are
immobilized and the labelled nucleic acid probe is allowed to hybridize
them. RNA probes specific for Potato spindle tuber viroid (PSTVd) have
synthesized from a full length PSTVd cDNA. and used successfully for
detection in potato. Improvements in hybridization assays have been
recent years using non radioactive detection systems. Nucleic acid
be labelled by incorporation of biotin 11 UTP or digoxigenin tagged DTP
be detected by streptavidin or anti digoxigenin antibody enzyme
Biotin labelled probes have been reported for PVS PVX and PSTVd.
chain reaction (PCR) combined with reverse transcription (RT PCR) has
used for detecting picogram quantities of viral nucleic acid in
tissues. With its relative simplicity and high sensitivity the PCR
methods will be increasingly used in future to detect and diagnose
propagation allows large scale multiplication of virus free potato
plants. Nodal segments of virus free potato microplants are cultured on
semisolid or liquid medium under aseptic conditions for obtaining new
microplants. Murashige and Skoog s (MS) medium supplemented with 2.0
calcium pantothenate 0.1 mgl GA 0.01 mgl NAA and 30 gl sucrose is best
for propagation of potato microplants in vitro. Cultures are usually
under a 16 h photoperiod (50 60m mol m s light intensity) at 24 °C.
nodal cuttings (1.0 1.5 cm) are inoculated per culture tube (25x 150
the tubes are closed with cotton plugs. Within 3 weeks the
of these cuttings grow into full plants. These plants can be further
cultured on fresh medium. At an interval of every 25 days of sub
3 (14.3 million) microplants can be obtained from a single virus free
microplant in a year.
plants can be used for direct transplanting after hardening in the
nursery beds for production of normal tubers or minitubers
Alternatively these plants can also be used for the production of
in the laboratory. Microtubers are miniature tubers produced under
inducing conditions in vitro. These small dormant tubers are
convenient for handling storage and distribution. Many protocols have
developed for induction of microtubers in vitro. Most of the published
potato microtuberization is focused on the use of cytokinins especially
benzyladenine (BA). Other substances like abscisic acid chlorocholine
(CCC) NAA triazoles coumarine acetic acid and jasmonic acid have also
for induction of microtubers in potato. MS basal nutrient mixtures are
universally used for potato microtuberization. Sucrose is the most
carbon source and an increase in its concentration to 8% induces early
tuberization whereas concentrations above 8% are inhibitory.
photoperiod are two important physical factors that affect potato
induction in vitro. The optimum temperature for in vitro tuberization
with a constant temperature being more effective than alternating day
temperatures. Temperatures below 12°C and above 28°C have been found to
inhibitory to potato microtuber production. In general optimum
microtuberization occurs under continuous darkness during cytokinin
tuberization but a longer photoperiod with higher light intensity is
when cytokinin is not used.
Central Potato Research
Institute (Shimla) microtubers are induced in MS medium supplemented
mgl BA plus 80 gl sucrose and the cultures are incubated under complete
darkness at 20°C. Microtubers begin to develop epigeally 1 2 weeks
incubation depending on the genotype and are harvested after 60 75 days
incubation. In general 15 20 microtubers with an average weight of
150 mg can be obtained from each flask/magenta box. Before harvesting
magenta boxes are shifted under diffused or artificial light at 20 24°C
15 days for greening the microtubers. Thereafter green microtubers are
with 0.2% Bavistin dried at 20°C packed in perforated polythene bags
under dark at 5 6°C till dormancy release. These microtubers are
nursery beds under aphid proof net houses (50 microtubers/m2) in seed
areas of the Indian plains. The microtuber crop is allowed to mature in
nursery beds to produce minitubers.
True Potato Seed
Potato unlike other
solanaceous crops such as tomato
brinjal chilli capsicum etc. is traditionally grown vegetatively by
called seed tubers. Because of ease in planting tubers and other
operations the vegetative or asexual mode of propagation became the
cultivation practice soon after the ancient farmers domesticated the
a food crop. Nearly 2.5 3.0 tons of seed tubers are needed to plant a
of potato crop. Seed tubers are bulky containing nearly 80% water that
their transportation from one place to another difficult and expensive.
degenerate due to infiltration and accumulation of viruses when the
stocks are repeatedly used over the years resulting in serious yield
This necessitates replacement of old or diseased seed with fresh
The production of healthy seed tubers is expensive and the low rate of
multiplication (normally 6 8 times) provides only a limited quantity of
tuber seed. Further the low aphid areas suitable for producing healthy
the country lie in northern plains or higher hills and transportation
of seed tubers
to distant areas for producing table potatoes adds to the cost of seed
cropping. Therefore the high cost and inadequate availability of
seed are most binding constraints in the production and productivity of
in the country. To overcome this an alternate technology of true potato
(TPS) or use of botanical seed for commercial potato production has
promise for producing both disease free and cheaper seed and thereby
the cost of cultivation.
ROLE OF TPS POPULATIONS
TPS is a
sexually reproduced propagule in potato and results from the
ovules which develop into tiny seeds inside the fruit called berry. The
thus produced is called TPS or botanical seed to distinguish it from
conventional tuber seed. True seeds have the potential to develop into
grown plants and produce tubers.
Potential and advantages of TPS technology
TPS has an
over tuber seed for various attributes of potato production (Table 1)
can effectively overcome some of the problems associated with seed
can be used easily by the resource poor farmers to produce healthy
material in any quantity as and when required. It offers many
advantages to the
farmers to overcome weaknesses of clonally propagated tuber seeds.
healthy planting material except potato virus T (PVT) and potato
viroid (PSTVd) no other major pathogen is transmitted through TPS as
filtered out during pollination and fertilization.
tubers for consumption nearly 18% of the total tuber produce retained
can be used for consumption.
Low cost of
cultivation Cost of planting material produced through TPS is
tenth of the cost of quality seed tubers.
with 3 5% seed moisture can be stored for many years under ambient
in dark with practically no loss in germinability at least up to 5
inexpensive transportation only 100g of TPS can replace 2 3 tonnes of
tubers required for planting one hectare land.
cultivation in non traditional areas TPS can be used for potato
areas deemed unfit for producing quality seed tuber due to unfavourable
potato in different cropping systems TPS can be used to fit potato in
cropping systems when tuber seed of correct physiological age is not
as and when required for planting the crop.
friendly the pathogens unlike in clonally propagated crop are unable to
TPS crop due to in built resistance (multi line effect) for
Consequently less amount of pesticides is needed for spraying TPS crop.
TPS is not only cost effective but also environment friendly.
Constraints/shortcomings in the adoption of TPS technology
following disadvantages which have been the major bottlenecks in
crop takes about 15 20 days more for maturity compared to that from
are vulnerable to environmental stress and damage due to insect/ pests
more care/labour input especially during the initial phases of growth
establishment in transplanted crop.
populations are less uniform in plant type/maturity tuber shape size
potato seed has a dormancy of about 6 months. Low quality and dormant
usually does not germinate uniformly and produces slow growing
are highly vulnerable to transplanting shock. Thus plant maturity is
and production of large tubers is delayed or small tubers are produced
the usually short growing seasons in tropical areas. When high quality
dormant TPS is sown the seedlings are uniformly ready for transplanting
3 weeks instead of 6 weeks. Seedlings from non dormant TPS unlike those
dormant ones are able to withstand bare root transplanting shock and
vigorously soon after transplanting and to a size similar to those of
grown from seed tubers.
American farmers have been
using TPS to revive their potato stocks from time to time. However the
exploiting TPS for commercial production of potato was conceived as
1949 in India when Dr. S. Ramanujam founder Director of Central Potato
Institute (CPRI) carried out field trials on utilizing TPS for ware
production. The self pollinated seeds of cultivar Thulwa which flowered under natural
pholoperiods during winter season in the eastern plains were used for
the commercial crop. Seedlings from self seeds of Phulwa showed high
heterogeneity for most of the traits and resulted in poor yields due to
inbreeding depression. This did not encourage the earlier efforts of
commercial potato crop from TPS. The programme of raising crop from
was resumed in late seventies after CIP was established in 1973. They
identified TPS technology as one of their thrust area for the third
countries. The work was started in India at the Central Potato Research
Institute Shimla and at International Potato Center (SWA Region). New
The efforts for reducing the problem of segregation in the progenies by
developing inbred lines were given up. Instead the early efforts
on evaluation of open pollinated and hybrid populations developed
parental mating in tetraploid potato for identification of progenies
productivity and low variability for maturity and tuber characters.
also taken up on standardization of agronomy of raising the crop
The studies were later extended to flowering behaviour induction of
under short photoperiod techniques of pollination TPS characteristics
Since 1985. The All India Coordinated Potato Improvement Project
network of centres all over the country located in State Agricultural
Universities (SAUs) has been involved in conducting trials mainly for
evaluation of high yielding TPS populations.
for TPS dissemination TPS technology has a wider scope for its adoption
areas where quality tuber seed of a variety can not be produced yields
extremely low due to availability of poor quality seed tuber storage
transportation are expensive skilled labour is available and consumers
have any preference for specific tuber characteristics. In the Indian
perspective TPS technology is suitable in the states of Maharashtra
Pradesh Orissa north eastern hill states (in the first priority) where
are extremely low (< 10t/ha) due to poor quality seed tubers
Bihar and West Bengal (in the second priority) where seed tubers of
health standard can not be produced and are procured regularly from
part of the country.
Economics of TPS technology
potato cultivation in conventional system is mainly due to higher
planting rate (2.5t/ha) of tuber seed. The cost of planting material
is merely one tenth the cost of tuber seed (Rs.25000 30000) for one
Singh and Jee have shown higher net returns for seedling tubers (Rs. 19
and seedling transplants (Rs. 19 174 ha) as compared to seed tubers
(Rs. 11 566
ha) of a variety under Patna conditions. Another study also indicated
net benefits (US$ 415/ha) from potato cultivation through seedling
tuber seed due to reduced production costs and improved yields.
are planted at relatively lower rate (by weight) and are resistant to
blight than the existing varieties in the area. Thus the difference
crops from TPS and traditional seed tubers primarily relate to lesser
expenditure on planting material and use of pesticides in TPS raised
compared to seed tuber crop. The price of seed tubers in India vary
price of ware potatoes increasing rapidly as cold store stocks are
potato is an important input needed for harnessing technological
potato cultivation. About 3.3 million tonnes of certified seed is
the area existing under ware potato in the country 35 q/ha. When
of seed is used (cut under size and whole tubers) But if the whole
tubers of 30
80 g are used then 4.6 million seed is required for seed and ware
q/ha for 1.3 million hectare area. To produce this quantity of seed
to 2.8 lakh hectare area is needed annually. The major constraints in
potato productivity are disease free seed and its higher seed cost.
for seed production in India was started in 1941 at Shimla by the
(now) Agricultural Research Institute New Delhi. Under the scheme
disease free seed of exotic varieties used to be produced by intensive
in the hills. Lateron production of quality seed stocks of commercial
was taken up by mass selection. The selected apparenly healthy plants
multiplied at Kufri. Because of low aphid population in high hills of
Pradesh quality seed of potato used to be produced in these high hills.
becomes the main source of quality seed for plains? Seed potato posed
problems. These were (1) it became obligatory to have varieties that
perform well under diverse agroclimatic conditions of both temperate
subtropical plains. (2) Dormancy of hill grown seed prevented immediate
planting in the plains (3) mild hill climates harboured many soil borne
diseases and the hill grown seed was a potent source of many soil and
borne diseases and (4) due to limitation of land in the hills the seed
in the hills was Inadequate to meet the requirement of entire country.
overcome these problems and to reduce the dependence of the country on
grown seed a survey was conducted to locate the aphid free zones in the
and it was found that seed potatoes could be successfully grown in many
of the North and north central Indian plains under low or no aphid
certain minimum precautions. This led to the development of Seed Plot
development of Seed Plot Technique a Scientific Seed Potato Production
Programme of breeder seed was initiated at the CPRI in 1967 in a phased
The breeder s seed production method consists of selection of clones
indorsing of representative tubers (4 Nos) from each clone for their
freedom some important points taken in to consideration as stated by
Morrenhof Virus free tubers by indexing and their field multiplications
stage 1 to 4 under strict supervision to protect the seed crop from
diseases. Integration of meristem culture and micropropagation
the initial stages of breeder s seed production can improve the quality
breeders seed. The breeders seed is further multiplied in foundation
certified seed stage.
As a rule seed tubers are
used for planting. These
tubers basically do not differ from tubers that are used for
purposes. Sometimes farmers use part of their own harvest as planting
for the next season. However in many places farmers do not use their
produce but purchase seed from reliable source every year or after a
years. The reason is that not every potato is suitable to be used as
that not every area and every season is suitable for the production of
Further more not every farmer region or country possesses the skills
and or the
necessary equipments and infrastructure which are required for the
of good quality seed. The use of quality seed is not only the basis for
production and good quality but also of a sustainable production
difference between the use of seed potatoes of good or of inferior
express itself in yield differences of 20 to 50%.
Some varieties can
be grown in many places and have a wide range of adaptability others
for very specific purposes or for specific environmental conditions.
production capacity an important varietal characteristic is the
pests and diseases. Varietal purity is an important requirement for
seed lots. Admixtures of other varieties will result in varying
with respect to agricultural practices like fertilizer harvest time
rouged out before harvest. They will also affect the marketability and
It is essential
to know which diseases/pests are important under prevailing conditions
level of risk they impose. It can then be decided whether more or less
strictness is required regarding their persistence in the seed.
tolerance levels are established for each of them. In some cases the
will be zero especially in the case of quarantine diseases which are
be seed and soil borne and which are not generally present in the
country or in
a certain area. The seed production system should be based on a proper
When a crop
is infected with virus its yield will be affected. The rate at which
reduction will take place depends on the intensity of the infection the
virus and the combination of other yield affecting factors that are
crop that is already under stress from other factors will suffer more
virus infection. In general a low infection level will have little
the yield but high infection levels can result in yield losses upto 50%
in case of dangerous viruses like potato virus Y (PVY) or potato leaf
virus (PLRV). If proper measures are not adopted to control the spread
viruses the infection level will increase progressively from one
next when the potatoes are produced. Gradually or reduction in
the crop is observed in successive generations. This process is called
The degeneration speed and severity is not the same every where it
presence of vectors and sources of infection available. Degeneration
warm climate is higher.
production of the lower seed classes (later generations) is done in the
and follows the same principles every where in the world. Only the
multiplications and the level of quality maintenance may differ. For
production of basic seed however there are some distinct approaches
that can be
followed. The conventional system is through clonal selection which
place in the field. Newly developed systems are the rapid
techniques using laboratories and green screen houses.
In the past
selection was the only system available for the production of basic
Typically true to type and apparently healthy looking plants were
start the cycle. The progeny of one plant formed a clone. The clones
separate from the others during three to five years of multiplication.
the same year several clones of several varieties were multiplied side
by side depending
on the expectations of the future seed demand. During the whole process
health and quality characteristics are strictly monitored and in case a
diseased from the system. After two or three multiplications the
clones of one variety were bulked and constituted as one lot. The thus
pre basic seed was (or has to be) absolutely true to type and free of
diseases. Presently starting a multiplication cycle absolutely true to
disease free material must be obtained. This is done by growing a
culture of shoot tips of true to type and healthy plants under sterile
conditions in a tissue culture laboratory. From the culture small plant
are raised invitro which are kept in test tubes or small transparent
containers. These invitro plantlets can under aseptical conditions be
small pieces each consisting of a piece of stem with one node which are
placed in tubes or containers on a growing medium. From the bud present
node small shoot will develop which will develop into small but
plantlet. The procedure can be repeated as often as desired. It takes
month between cuttings and each plantlet can be cut into 5 to 8 pieces.
desired moment the plantlets can be transplanted in green houses and
grow into normal size plants producing normal tubers. As the plantlets
vulnerable they are normally passed through a hardening process in
screen houses before entering the open field. Alternatively they can be
directly in the field under protective nets.
plantlets in test tubes nodal cuttings can also be taken from bigger
When laboratory space is limited the in vitro plantlets can be
the tubes to pots in green houses. After some time nodal cuttings can
from the stems of these plants which can be rooted in soil sand and FYM
(1 1 1) to be grown into normal plants (either or not via
the new shoots growing from the same mother plants the process can be
two to three times. Then they are left to grow to maturity. Mini tubers
produced from in vitro plantlets after they have been planted at high
(100 plants per m_) in beds in green or screen houses. The plants
and consequently small tubers are produced. Mini tubers of 15 25 mm
preferred. The mini tubers thus produced can be planted directly in the
and enter the seed production chain. When compared to clonal selection
tuber production requires high investment in laboratories and green
makes it more expensive. The advantage however is the fact that the
been less exposed to infections with diseases than the clones that have
been in the field for a number of generations. This may be of
importance in places where high degeneration rates prevail or a disease
serious nature occurs in the region.
SEED PLOT TECHNIQUE
production on scientific lines in India has been started since 1966
technique which is known as seed plot technique. The main aim of this
is to exploit the vector (Aphid Myzos persicae) free period in the
plains with adjustment of planting and lifting dates and by adoption of
appropriate plant protection management and method of cultivation for
requirements of the crop grown for seed differ from ware potato
Different practices followed in seed plot technique are discussed as
and preparation of field
The potato crop should not be repeated in the same field. The
potato in chilli brinjal tomato and okra crop rotation is not
that the disease intensity would be lowered down. Adoption hot weather
cultivation and 2 3 years crop rotation is recommended to avoid buildup
borne pathogens such as black scurf and common scab etc. Minimum
distance of 25 metres from the ware crop should be kept.
Field in which potato seed
crop is to be grown
should be deep ploughed during summer and left as such. This will help
controlling certain pest and diseases and also the weeds.
should be healthy essentially free from
the viruses soil borne diseases like bacterial wilt common scab and
etc. genetically pure and of uniform size. Genetical purity is of great
importance in potato seed production programme. The identification of
varieties at their sprouting stage can be possible. A reliable method
has been developed
using the sprout grown in the light. Another method employed now a days
sample from the seed stocks and plant them under long day conditions
flowering is obtained to determine whether the variety is true to the
not. The minimum size of seed accepted is 28 to 35 mm and maximum size
permitted for seed potatoes can be as large as 80 mm but often not more
to 60 mm. Generally 15 stems per m_ should be there small tubers have
sprouts than bigger ones but their weight is also lower. Morrenhof
that to around 15 00 000 obtain stem per hectare 60 000 tubers
1500 kg are required when size of 28 35 is used against 30 000 tubers
equivalent to 2700 kg when the size 45 55 is planted under Netherland
seed tubers before planting increase the number of stems per tuber and
hastens quick uniform and full germination. The seed stock of early
should be withdrawn from cold storage at least 7 days before planting
and that of
late varieties 15 days before planting. The number of sprouts from a
depends on a function of variety physiological age of tuber and the
of the chamber in which the seed is kept for sprouting. An ideal
for sprouting is 10 12°C.
varieties have been completely cured of PLRV by heat treatment at 35°C
days and at 36°C for 39 days Thirumalchar demonstrated this in the
stored in improvised stores under warm conditions at Patna.
size and spacing Whole
potato tubers of about 45 50 g are used for seed crop. Tuber number is
function of plant density which depends on the number of main stems.
combination of seed size and spacing is therefore essential to get the
of required stems per ha. About 30 main stems per m yield maximum seed
tuber. For this there must be 70 000 80 000 plants per ha. In India
careful manipulation of sprouting tuber size spacing and time of
average of 4.5 stem per plant can be achieved with seed tubers between
20 25 g
when spaced at 50 x 20 cm 50 100 g seed at 60 x 25 cm and 100 g and
above at 60
x 30 or 60 x 40 cm. 10 20 g tubers at spacing of 40 x 15 cm seed
maximum quantity of C grade tubers (>25 g in weight) which are
of planting In hills
the planting time is mid April. It may differ because of temperature
In plain the planting time ranges from first week of October to 1st
November depending upon the region. The temperature should be ranged
to 28°C during the crop season.
fertilizer requirement will vary with soil and previous crop taken. In
about 120 150 kg N 80 100 kg P2O5 and 100 kg K2O per ha may be used in
crop. Heavy application of nitrogen may delay tuberization masking of
symptoms and delay in maturity.
irrigation should be given to the crop immediately after planting if
planting irrigation is not given. Pre planting irrigation assures the
emergence. Second irrigation should be given about one week after
subsequent as and when required.
control Full earthing
up may be done at planting and pre emergence herbicides are used to
weeds and avoid spread of contagious viruses. Weed control through
method is generally not advised. Because the frequent entry of man and
implements are likely to spread contact viruses like. PVX and PVS. For
emergence weed control herbicides like Pendimethalin Alachlor
may be used.
Rouging and Inspection Diseased and off type plants
should be pulled
out along with mother tuber and newly formed tubers if any as soon as
identified. This practice should be repeated twice or thrice to avoid
admixture and keep the crop free from viral and phytoplasmal diseases.
Inspection of seed crops should be done 3 times at 50 65 and 80 days
growing season and remove all off types and diseased plants showing
viruses should be removed.
destruction is a must to prevent the infection/ transmission of virus
by aphid (Myzus persicae). The aphid population starts building up in
of December or 1st weeks of January. At this stage haulms should be
either manually or by using the chemicals. Paraquate Chloride @ 2.5
most effective for killing of haulms. Singh et al. After removing of
field should be inspected periodically and regrowth if any should be
management This is
one of the most important practices of the Seed Plot Technique. The
population should be recorded periodically and when it reaches above
threshold 20 aphids per 100 compound leaves dehaulming should be
There should be at least 75 days low aphid period or aphid free period
an economical yield could be obtained from early bulking varieties. In
effective aphid free period is too short. The crop can be escaped from
of aphids if it is harvested early. In such areas reasonably healthy
good yield can be produced with the management of aphid population
threshhold level with the use of systemic insecticides like.
(100 125 ml in 100 litres of
water). In case of early appearance of aphids spraying of crop should
in first week of December.
and Pest Management The
potato is prone to number of diseases. The seed should be free from
diseases and pest so that the crop is not economically affected in
quality. Viral diseases are particularly important in potato seed
programme. The control of fungal bacterial namatodal diseases also
the value of the seeds potato. Use of granular insecticides such as
Thimet 10 G
(15 kg/ha) at the time of planting is essential in plains to control
aphids. Spray the crop with Endosulfan 1.5 lit/ha or corboryl 2.5 kg/ha
sprayed if leaf catterpillar damage is noticed. Ridges are treated with
chloropyriphos 2.5 lit/ha to control the damage of cut worm. One spray
or Metasystoc in the first week of December will check the aphid and
sucking type of pests. One or two protective sprays of Dithane M 45
kg/ha against early and late blights are required. When epidemic of
is observed Ridomil Metalaxyl 2.5 kg/ha should be sprayed. Spraying
done from 3rd week of November at 10 days interval.
and storage Harvesting
should be done after 15 20 days of haulms cutting so that the skin of
gets hardened. Delay in harvest will spoil the quality due to high
in March April in the plain s. The harvested tubers should be kept in a
place for about 15 days for curing. Seed tubers should be graded before
to the cold store. The small size tubers should be kept as seed tubers.
grading the tubers are washed with 1% chlorocin solution followed by
water and dipping in 3% boric acid for 20 minutes. After treatment the
dried in shade and packed in gunny bags then labled and sealed and kept
Conditions of Growth for Potato
is a versatile crop and
can grow under diverse range of Agro climatic condition. The potato is
of temperate climate and thrives well in cool climate. In general
cool condition (15.5°C 21.1°C) are most favourable for the growth of
tuber formation. In the hot weather of mid summer plant may produce
but set few tubers.
wide range of seasonal adaptability. In the Gangetic plains of Uttar
time of the crop can be extended from mid. September to almost mid
about four months an advantage which perhaps no other crop enjoys. In
and Western district of Uttar Pradesh two crops can be raised in
the same price of land the first sown in September October and the
December January. In Southern India where summer temperatures in the
region are somewhat milder two crops one in winter and other in summer
raised. It should be recognised that very few crops can be raised
both in Rabi and Kharif season in the same tract. In the Nilgiri Hills
potato crops are raised almost in succession the planting month being
is a summer crop in the hills where it is long day crop and a winter
the plains where it is a short day crop. It is possible to cultivate
one crop in the plains by adjusting the time of sowing. Low temperature
light intensity and short days are conductive for early initiation of
tuberization and its subsequent development. It grows best under long
condition. In short day and warmer temperature flowering in potato is
restricted and sometimes completely suppressed.
cultivated as a rainfed as well as irrigated crop. High rainfall and
are detrimental to this crop though it requires regular irrigation for
plant growth and tuberization. Soil moisture stress results the lower
potato. Potato is sown in the plains when rains are over as it fails
rain. But it needs frequent but light irrigation usually form 6 8
The water requirement of this crop is 25 26 hectares centimetre.
exercises a marked influence on plant growth and tuber development. The
temperature affects biochemical reactions and though these influences
growth and development in crop plant. Potato can stand temperature
10°C (50°F) to 26.6°C (80°F) but average is 21.1 C (70°F). The average
temperature of 15.5°C to 18.3°C (60 65°F) are preferred although prior
tuberization slightly higher temperature give the best growth.
According to Mac
Gillivary tuberization is best at soil temperature of 17.7°C (64°F).
according to Choudhury tuber production is maximum at 20°C (68°F) and
with the rise of temperature. At about 30°C (70°F) tuber production
totally as at this temperature carbohydrates consumed by respiration
those produced by photosynthesis. The work carried out at CPRI Shimla
that night temperature of 15°C 20°C (59°F 69°F) are optimum for greater
yield in pre tuber initiation phase and 15°C (59°F) in the post tuber
phase under short day. With the increase in temperature from 10°C 30°C
70°F) or 15°C 25°C (59°F 75°F) there was greater extension of growth of
and accumulation of dry matter in stem. Jones et al. have found a clear
influence of soil temperature. 15°C to 18°C (59°F to 64.4°F) being
Higher temperature induces respiration to go up and less carbohydrates
is left for
the tubers. Heal necrosis may also be caused by higher temperature.
temperature with longer days and an abundant supply of nitrogen favour
growth of all plants except the tuber while the low temperature with
intermediate days and deficient nitrogen caused early tuberization. The
temperature is also important since this determine the rate of
respiration of the
tuber. A number of worker have obtained increased yield by mulching as
to reduce the soil temperature. Irrigations may also reduce the soil
temperature. Under cool and short day the plants were small and had a
ratio of tuber to top. Joshi et. al. studied the effect of night
and photoperiods on chlorophyll content dry matter and tuber yield in
Plant exposed to long days at 15°C and 25°C showed higher chlorophyll
and dry matter than the plants grown under short days at respective
temperature. There was marked decline in chlorophyll dry matter and
production at 25°C night temperature under short days as compared to
1. Effect of night
temperature and photoperiods on chlorophyll dry matter content and dry
even lower temperature provided frost does not occure. Under higher
plants are elongated leaves become wrinkled and plants have sickly
Tuber does not develop under such conditions.
It grows at
elevation ranging from sea level to 2743 meters high. In India potato
upto 2100 meters high from sea level. Bulk of this crop is mainly grown
plains. It has been found that potato thrives best under short day
coupled with abundant sunshine and cool nights. Cloudy days rains and
humidity are very congenial for spread of fungal and bacterial disease.
various physiological process of the plant such as chlorophyll
and closing of stomata photosynthesis respiration and transpiration. It
promotes sprouting in tubers of potato but once it has taken place it
their excessive elongation. The intensity and duration of light is
for higher yield and quality of tuber due to increased photosynthesis
must remain covered under the soil to avoid sun scalding. In general
that are conductive to production of very large tubers may cause hollow
in the tuber. Tubers are storage organs and in case of potato starch is
reserve food which is synthesized in plants from sugar formed during
photosynthesis. The amount of sunlight the plant receives determine the
photosynthesis to the great extent and directly influences the amount
carbohydrates available for tuber growth.
formation in potato is a response of the plant to photoperiodic
Potato has been classified as a short dry (SD) and long day (LD) crop
tuber initiation response. In the plains of India the crop is taken
short days of winter and under this condition tuber initiation is early
plant is stunted giving bushy appearance bulking is rapid and maturity
advanced. On the other hand under LD conditions prevailing during crop
in summer in hills tuber initiation is delayed plants are tall and
season is prolonged. The ratio of tuber to foliage which is an index of
efficiency of plants in crop production is greater under SD than under
condition. The effects of suboptimal number of SD separated by non
are not additive on tuber initiation in Potato. The foliage exposed to
would initiate tuberization is called induced foliage . Light also
respiration indirectly through temperature. The potato is LD plant in
flower initiation response. It is found that almost all the varieties
flowering in hills where the potato is cultivated during long days of
In photoperiodic reaction it is revealed that red and far red light
potato is poor in India due to its growing in short day period because
this time carbohydrates production is low.
can grow well in all types of soil except alkaline soil and soils with
clay content. Sandy loam loamy soil and sandy soil rich in organic
most suitable for potato cultivation. Heavy and wet soils are not
potato. The soil should be loose and friable with aeration and good
potato is very sensitive to excess of moisture which causes rotting of
So drainage is most important for successful cultivation of potato. The
with pH around 5.0 6.5 is considered to be best for potato cultivation.
Slightly acid soils (pH 4.8 5.4) are preferable for potato cultivation
especially for areas where scab disease is prevalent. It cannot
alkalinity in the soil since alkali soils create favourable condition
disease. Heavy soils are not suitable for the growth and development of
But the heavy soils that are manured heavily with manures such as
Oil cakes etc. are found suitable for potato cultivation. Potato grows
even in sandy soils if adequate fertilization is done. Heavy type of
difficult to work with and are not well suited for potato cultivation.
most suitable for potato cultivation during rabi season. In the hills
cultivated on the sloppy land after making terrace.
potato needs well pulverized
seed bed for tuber production. The soil is brought to a fine tilth by
10 ploughing followed by planking after each ploughing. The process of
levels the land breaks the clods loosen and collect the weeds and
the soil slightly. The preparation of land is usually begin at 6 8
the sowing of potato during which 250 quintals of compost or F.Y.M. per
are applied to the soil. The soil should be made free from stubbles
clods. Now a days tractors and power tillers are employed for land
latter makes the soil more pulverize free from weeds and clods by
number of tillage than that of country plough.
cent 20 kg. or Texaphene 5 percent or Folidol dust 25.0 37.5 kg or
Chlorophyrifos (Pyriban 20% EC)
litre per hectare should be
applied with last preparatory tillage.
operations that are carried out to prepare the field for raising crop
harvest of a crop to the sowing of the next crop are known as
It is divided into primary and secondary tillage operation.
Primary tillage or ploughing
operation that is done after the harvest of crop to bring the land
cultivation is known as primary tillage. Ploughing is the opening of
soil with the help of different ploughs. Primary tillage is done mainly
the hard soil and to separate the top soil from lower layers and to
of weeds also. Potato is a crop whose growing season is short and whose
planting time is restricted. Speedy agricultural operations are a basic
several implements used for primary or preliminary tillage as follows
Plough. It is an
indigenous plough and is one of the most common implements used by
It is drawn with a pair of bullocks. It is used both for tilling the
harvesting of potato. The country plough works to a depth of 10 15 cm.
opens out a furrow of 12.5 to 17.5 cm. The plough can work up about
hectare per day in the initial ploughing and subsequently the
increases to about 0.20 hectare a day.
board plough. It is
most suitable for primary tillage of almost all types of soil. It cuts
furrow and the soil is inverted completely depending on the curvature
the mould board plough and thus help in burying the weeds. The mould
plough ploughs to a depth of 15 cm having width from 15 to 35 cm. It
0.20 0.26 hectares of land in a working day of eight hours.
plough. It is a
modified form of mould board plough. It is made of wood except the
is made of steel or iron. The structure and function of this plough is
similar to mould board plough. This plough is gaining popularity among
farmers. Most of the farmers of our country are using this plough.
plough. It is also
used for ploughing which have little resemblance to common mould board
It is clod breaking implements which is invariably used for initial
in hard soil. It can cover about two hectares a day.
Spade is most
common implements used for various agricultural operations like bunding
ridging and harvesting of potato. It is used for breaking and preparing
soil when the land size is small. A man can dig about 0.08 hectare in a
It is most
important tools for mechanization of various farm operations and it has
a vital part of modern agriculture. Four wheeled tractor having average
power of 30 to 35 can be used for ploughing harrowing sowing harvesting
and belt work (i.e. cutting of chaff lifting of water etc.). The
wonderful piece of invention for the agriculture.
tiller. The power
tiller is generally used for plough
harrowing puddling and pumping
of water. It makes the soil pulverized very well and hurried the weeds
completely. The tilling capacity of a power tiller is about 0.25 acres
operations that are performed on the soil after primary tillage to
bring a good
soil tilth are known as secondary tillage. Secondary tillage consist of
or finer operation which is done to clean the soil break the clods and
incorporate the manures and fertilizers.
implements used for secondary tillage as follows
or Plank. It is an
age old implement used for secondary tillage. Planking is done to crush
hard clods level the soil surface and to compact the soil lightly. It
by a pair of bullock or tractor.
It is commonly
used for secondary tillage and is drawn by a tractor. Harrows are used
making the soil loose and friable. It can cover 1.0 hectares of the
land in a
working day of 8 hours.
It is one of
the most useful implements used for secondary tillage of potato field.
also be used for primary tillage cultivation and weeding purposes soon
the emergence of the plant. It can cover 1.0 to 1.5 hectares of land in
working day of 8 hours.
Khurpi Nirani etc. are also used for secondary tillage.
operations that are done in the standing crop after planting and prior
harvesting of the crop plants are called after tillage. This is also
inter cultivation or post planting cultivation. It includes harrowing
earthing up drilling or side dressing of fertilizer etc. Spade Nirani
hoe etc. are used for inter cultivation.
PLANTING OF POTATO
is grown in different periods in different parts of India depending on
ecological conditions. (Vide Table 1)
Selection of Seeds
Seed is the
on which the foundation of potato farming has to be laid. In fact in no
crop is the value of good seed so important as in the potato. With
seed over 50 percent of the problem of production of the growers can be
asexually propagated crop and it is propagated from tubers which are
spoken of as seed. Pure and healthy seed is the basic requirement for a
crop. Seed is one of the major inputs in potato production accounting
than 50 percent of total cost of cultivation. If the seed is low
other factors like good culture manuring and plant protection measure
of any help in securing profitable yield. Tubers showing any surface
diseases like scabs wart nematode infection or effect of rot caused by
and bacteria should be sorted out and destroyed.
the costliest item in the total cost of production and it also affects
yield of the crop. Seed is major input in potato cultivation accounting
50 per cent of total cost of cultivation. The following points must be
into account at the time of selection of tubers for seed.
tubers must be uniform in
shape and size.
tubers must be free from any
surface borne disease like scabs wart nematode infection or effect of
caused by fungi and bacteria as they carries a number of pathogenic
such as late blight charcoal rot brown rot black scurf etc. and
such as ring rot (C.O. Pseudomonas solanacearum) and also insect
moth which infects potatoes in the country storage often damages the
decreasing the seed value of the tuber. Mealy bug is another tuber
the country storage affecting the quality of seed.
tubers must be 2.5 3.8 cm in
size and 50 60 gm in weight. Small size tubers produce virus infected
seed tubers should be in
their right stage of sprouting so that it germinates quickly and
itself into a vigorus plant and the sprouts should be about one cm.
long at the
time of planting as over sprouted seed give rise to plants with poor
low yield. The seed tubers should be kept in cool place for about three
the eastern plains and one week in the North Western plains for
seed tubers should not be shriveled.
Because seed tubers which have shriveled in storage loose much of their
vitality. The use of such seed or over sprouted seed give rise to
poor vigour and low yields.
seed tubers should be true to
seed tubers should be
Source of seed tubers for commercial use
There are three sources of
seed tubers for
commercial use as follows
stored in country
cellers. It is old and primitive method of storing seed
varieties such as Kufri Safed Phulwa and Satha with good keeping
quality can be
stored in country cellars. The varieties like Darjeeling Red Round and
Red can also be stored in country celler with proper care and
potatoes that are stored in country cellar need desprouting once or
during storage to avoid their shrinkage. It does not withstand cutting
operation and has to be strictly avoided. The whole tubers are planted
field. The seed storing in the country cellars are fast losing
the popularization of seed preserved in the cold storage.
stored in the cold
storage. It is most useful and economical method of storing
seeds in large
quantities for autumn planting in the plains particularly when early
sought to be raised. The seed potatoes should be removed at least by
beginning of November from the cold storage as storage for long period
9 months) affects the seed value of the tubers adversely and such seed
develop into weak plant with several thin stem which mature early and
poor crop of small sized tubers. The seed potatoes after they are
cold storage should be dried and carefully sorted and should be kept at
one week in cool and shady place for sprouting. It is preferable to
tubers as the cold stored seed do not withstand cutting operations
successfully. However where cutting of large sized seed tubers become
and unavoidable it is best to suberise the cut surface in cool place
planting in the field. The cold stored seed cannot withstand transport
long distance in the plains during September October. For this it is
use such seeds locally within the juridiction of the cold storage. The
tubers need to be transported in the distance place should be dried
carefully in the shade of the cold storage and then transported.
produced in the hill
areas. Potato is cultivated in the summer season in the hill
the harvesting is done in the month of October. These potatoes are used
in the plains. But this seed tuber cannot be used immediately after
they are partially dormant. They are profitably be used as seed tuber
place where planting is done late i.e. between November and January.
withstand rough handling and can be transported over long distance in
bulk or in bags in which respiratory activity warms up the stock during
which help to force the tuber to sprout. If the stocks are still
short period of storage in a warm place before planting is desirable.
ensures quick and better germination of seed potato.
produced in the hills is invariably used as cut seed. This is highly
practice for the following reason.
produce usually consists of
large sized tubers it is uneconomic to sow large sized tubers cutting
considerably lower the seed rate per hectare.
seed is often in a
semidormant state cutting of tubers and planting then immediately after
moist soil helps to overcome the dormancy and results in better
DORMANCY OF SEED POTATOES
are living entities with high rate of metabolism and they do not keep
under prolonged storage unless special precautions are taken. Potatoes
susceptible to three main types of deterioration in storage Shrinkage
time taken from harvest to the initiation of sprouting is termed
after harvest tubers have a rest period or dormant period during which
will not sprout even through placed under suitable condition. So
been defined as that condition of potato tubers in which they fail to
under environmental condition that are otherwise suitable for sprouting.
dormancy is of a great significance under Indian condition of culture
when seed from the hills is to be used as seed soon after harvest. The
of dormancy varies from variety to variety and is influenced by several
external factors. After tuber formation the buds on the potato tubers
dormant for a period of time the duration of which is largely a
character although it can be modified to some extent by factors of
environment particularly temperature.
semidormant tubers will not germinate readily in the ground their
considerably delayed and often erratic and the crops will be uneven. On
basis of the duration of dormancy as calculated from the time of
harvest to the
first appearance of sprouts under condition otherwise favourable for
varieties can be broadly divided in the following three groups.
and their Management
the most dreaded disease limiting potato production in the subtropics.
severity of this disease is moderate in subtropics as compared to
climates lack of appropriate management technology in this region
heavy crop losses. The disease appears first as water soaked irregular
green lesions mostly near tips and margins of leaves. These lesions
grow into large brown to purplish black necrotic spots. During morning
white mildew which consist of sporangia and spores of the pathogen can
on lower surface of infected leaves especially around the edges of the
lesions (Fig. 1). Light to dark brown lesions appear on stems or
elongate and encircle the stems. The affected stems or petioles become
these locations and may collapse. Under disease favorable conditions
crop gives blackened blighted appearance and may be killed within a
infected tubers are initially hard dry and firm but may be invaded by
mainly bacteria and turn to soft rot.
Distribution and losses
severity is not uniform throughout the subtropical region. For example
it is most severe in temperate highlands followed by tropical highlands
subtropical plains. Even in the subtropical plains the disease is
more regular and severe in north eastern plains of Bihar Assam and
compared to western plains. These variations in disease severity are
due to the differences in weather conditions. In hilly regions losses
may go as
high as 80 90 percent in susceptible potato varieties not protected by
fungicides. Losses are generally low in plains where disease does not
every year. However in certain years these may go up to 25 per cent.
caused by Phytophthora infestans (Mont.) de Bary. It belongs to order
Peranosporales of class Oomycetes The fungus is coenocytic which
shaped detachable papilliate sporangia on sympodially branched
of indeterminate growth. The sporangiophores exhibit a characteristic
at junction where sporangia are attached with the sporangiophores. The
is hetrothallic and requires two mating types viz. A1 and A2 for sexual
reproduction. The fungus is believed to have originated in Mexico and
to the rest of the world. It caused the great historic potato famine in
during 1845 46.
The fungus is
very elastic and new pathogenic races of the fungus appear in field
overcome resistance of disease resistant cultivars. Ever since
major genes in Solanum demissum and their use in management of this
and more newer races of P. infestans have appeared throughout the
India only simple races (0 1 4) used to occur until 1965 but complex
started appearing in late sixties with the introduction of late blight
resistant cultivars such as Kufri Jyoti Kufri Khasigaro and Kufri Muthu
and by end of 1980 eight to nine gene complex races became quite
particularly in hilly regions.
pathogen could arise through mutation somatic hybridization adaptive
or sexual reproduction. Sexual reproduction prior to 1980 s was mainly
restricted to Mexico but recently it has been found operative in many
and Asian countries including India.
infestans mainly survives through infected seed tubers kept in cold
the plains and country stores in hilly regions. Under temperate
fungus can survive in refuse pile in infested vines and tubers.
plants can also serve as primary source of the pathogen. The pathogen
survive as oospores which are produced sexually through mating of Al
and cytogenetics Sporangium
of P. infestans is multinucleate. Both migration of nuclei from hyphae
division within the sporangium initially give rise to multinucleate
Degeneration of nuclei coupled with nuclear division occurs in detached
sporangia before formation of zoospores. P.infestans in contrast to
fungi resembles higher organisms in being diploid in the vegetative
meiosis occurring before gamete formation. The pathogen can occur as
or tetraploid. Polyploidy in P.infestans could be one of the reasons
variability arising within the fungus.
late blight and its subsequent build up and spread depends on several
These include sources of inoculum plant protection support provided
fungicide sprays deployment of host resistance in field and weather
seed tubers left in soil and refuge piles in the temperate regions and
tubers cold stored in subtropical regions serve as primary source of
disease. The fungus may also survive as oospores in soil but the extent
their contribution to primary inoculum is not clear. Similarly role of
and tomato stalk and infected true potato seed in the perpetuation of
disease is not certain.
of late blight depends on inoculum load host resistance and weather
Weather conditions play a decisive role in the appearance and build up
blight. At nearly 100 percent relative humidity sporangia of the
appear within 8 hours at temperature range of 18 to22°C. The sporangia
prone to desiccation but can remain viable for several hours at
humidity while attached to sporangiophores or after they are deposited
surfaces. Optimum temperature for indirect germination through
12°C. It may take only 30 minutes to produce zoospores at this
zoospores are disseminated by splashing rain drops and cause rapid
of disease in field.
1. Late blight caused by Phytophthora
infection on potato leaves
produce germ tubes and appresoria in the presence of free water and
the host tissue within two to two and half hour at 10 to 25°C. Once the
penetration has occurred subsequent development of the disease is most
17 to 25°C. optimum at 21°C when lesion with fresh sporangia appear
within 3 to
5 days. Rainfall and soil temperature below 18°C result in higher tuber
day length and light intensity are known to influence resistance of
cultivars. Expression of race non specific resistance is better under
conditions. Host nutrition and virus infection in plants may also
reaction to late blight.
to forecast late blight have been developed but the most successful and
used models were Blightcast developed by Krause et al. and SYMPHYT
Bruhn and Fry. Computer aided decision support systems. Different
weather criteria may be required for forecasting potato blight for
regions. Based on local weather parameters a computerized forecast for
blight named as JHULSACAST has been developed for western subtropical
spread and build up Build
up and spread of late blight has mainly been studied in relation to
infection. Blight development around infection focus primarily depends
dispersal of P. infestans spores which is primarily restricted to short
distance although long distance dispersal has also been reported. Early
infection mainly occurs in lower leaves which later spread to all parts
plant. The disease develops more in the wind direction and the
inversely proportional to the distance from the disease source. Primary
focus is mainly limited to an area about 10 meters of the source.
infection foci develop around the primary source.
management of late blight would entail reduction of both foliar and
infection. This can be achieved by employing chemicals crop husbandry
and host resistance in an integrated manner.
systemic fungicides are important in the management of late blight.
molecules such as copper salts and Bordeaux mixture were used to manage
disease. Later discovery of dithiocarbamates replaced copper salts and
to widest use. Recently a new group of fungicides viz. phenylamides
a systemic fungicide have been proved to be the most potent fungicides
evolved. Within a few years of its development this has become a major
fungicide used in the control of late blight the world over. But
P.infestans resistant to metalaxyl have appeared both in India and
countries. To prevent development of resistance in the pathogen
best be used in combination with contact fungicides such as mancozeb.
fungicide Cymoxanil in mixture with the contact fungicides can be used
manage metalaxyl resistant isolates of the pathogen. Optimum use of any
fungicide can be made following disease forecasting systems. Heavy
on fungicides could pose threat to environment and human population.
community is now devising ways and means to reduce the use of
of naturally occurring biocontrol agents is considered a safe option in
of fungicides. Antagonism to P. infeslans by some naturally occurring
microorganisms such as Trichoderma viride Penicillium virdicatum
brasilense Acremonium strictum Myrohecium varrucaria Penicillium
avrantiogriseum Epiccocum pvtrpuranscens. Stahcybotrys coccodes.
syringae Fusarium graminearum and Pythium ultimum have been reported.
Biocontrol agents have been found effective against late blight disease
controlled conditions such as laboratory and glasshouse but less
field. An integrated use of biocontrol agents with low dose of
be the next best strategy.
methods aim at eliminating or reducing the initial inoculum load in
and other sources. Care should be taken to avoid tuber infection by
ridging covering the tubers minimizing irrigation after the blight has
and by cutting the infected haulms. The tubers should be harvested
skin curing and diseased tubers should be sorted out before storage.
Elimination of refuse piles in hills could also help to minimize
inoculum. It has been estimated that the onset of epidemic can be
delayed by 3
to 6 weeks if all primary infection from early potato can be eliminated.
EARLY AND PHOMA BLIGHT
caused by Alternaria solani (Ell & Mart.). Jones &
appearing on the potato crop just before the initiation of
disease continues to develop till death of the plants. Initially the
occur on the lower and older leaves in the form of small (1 2 mm)
oval brown spots (Fig. 2). These lesions have the tendency to become
angular at later stage. Mature lesions on foliage look dry and papery
have the concentric rings looking like bulls eye. The rings are more
in large blotchy spots and give them a target board effect. The spots
dry and brittle but some times under conditions of heavy dew or rain
and dark brown appearing somewhat like small lesions of late blight.
are distinguished from late blight by the absence of white mildew
growth on the
under surface of the spots. The spots are mostly 3 to 5 mm in diameter
some cases may be up to 10 mm. The spots may enlarge and coalesce to
necrotic areas. Ultimately the whole leaf dries up and hangs along the
The spots may also develop on the stem at a late stage of growth of the
tubers show dark brown lesions on the surface. These lesions are
sunken and are circular or irregular in outline measuring up to 2 cm in
diameter. The tissues underneath the surface of the spot show a brown
dry rot. This rot may be observed up to a depth of 6 mm and does not
further into the tuber flesh as may be observed in late blight affected
Tuber infection is rare in India.
caused by Phoma exigua Desm. are larger 1 to 2.5 cm in diameter with
alternate light and dark concentric zones. Affected tubers have grey to
greenish black depressed lesions on the surface upto 3 cm wide.
caused by Phoma sorghina Doerema Doren and van Kest are characterized
pinhead size spots which may be oval circular or irregular not
exceeding 4 mm
in diameter. Infected tubers show dark grey large lesions (up to 1.7
and severity of early blight and leaf spots is generally high in the
receiving imbalanced doses of NPK particularly low nitrogen. Early
occurs in all the potato growing areas. Disease appears in a severe
form in the
sub mountainous regions. Depending upon the severity phoma leaf spots
significant yield losses. It has been reported to cause losses up to 20
cent in Kharif crop in Ranchi and adjoining plateau region.
early blight is mostly influenced by moisture temperature variety of
and vigour of the plant. Optimum conditions for the development of the
in a severe form require high temperature alternating with moist
periods and a
poor vigour of the plant.
observed to be severe when the humidity was high early in the season
by high temperature. Conidia of A. solani were found to infect the crop
after being exposed to freezing temperatures on the surface of the soil
buried to a depth of 5 to 20cm. The conidia can germinate and the
grow in culture at temperatures ranging from 1° to 45°C with an optimum
to 28°C. The development of the disease in the field is severe at day
temperatures of 25° to 32°C. The laboratory studies showed that
temperature of 26ºC was optimum for the development of infection in
pathogens viz. A. solani P. exigua and P. sorghina can infect tubers
capable of surviving during storage. These pathogens can also survive
and plant debris particularly in temperate climate. The infected tubers
the primary source of inocula for both early blight and leaf spots. In
diseases are favoured by moderate temperature (17 25°C) and high
75 per cent. Intermittent dry and wet weather is more conducive for
season infection initially appears on the lower leaves near the ground
and results in the infection of young immature tubers if not covered by
soil. The affected tubers when used as seed serve as potential source
disease in the subsequent season.
for Potato Production
Since independence increasing
emphasis has been
given to agricultural development. The inputs necessary to increase
productivity namely seeds fertilizers irrigation fuel etc. were made
at subsidized rates to encourage their use for maximizing the crop
productivity. This intensive crop production strategy was called the
Revolution technology. The intensive use of inputs is now creating
like declining soil fertility soil erosion environmental pollution due
agricultural chemicals chemical residues in foods pest outbreaks and
in distribution of benefits of agriculture. Therefore there is now an
increasing emphasis the world over towards low input agriculture.
1. Break up of the operational
cost of cultivation in potato
INPUT INTENSIVENESS OF POTATO CULTIVATION
the most input intensive crops. Compared to rice and wheat potato
is 2 3 times costlier. For any further increase in the area under the
its better utilization there is a need to make it less expensive. About
of the cost is for seed followed by labour (human bullock and
together). Fertilizer and manure and irrigation are the other main
inputs in potato production (Fig. 1). These costs are incurred when all
cultural operations and inputs are given at the optimum level and are
requirement ranges from 25 40 q/ha. In the Indo Gangetic plains the
in the autumn season is after cold storage. Therefore there is an added
storage of seed potatoes from February/March to September/October. As
are bulky the transport from the cold stores to the fields involves
considerable cost. Moreover after removing the seed tubers from the
they have to be kept in shade for about 10 15 days for chitting of the
rotted tubers etc. These operations involve labour and money adding to
while the cost of seed handling is generally very low in other crops.
more labour (both mechanical and human) as compared to other crops. In
crop land preparation planting weeding earthing up and harvesting
are the major field operations involving considerable energy and cost.
preparation is more intense for potato since a fine tilth is required
prepare a ridge for easy penetration of root better development of the
and enlargement of the tubers.
fields are large planting has to be done mechanically using a tractor
semi or fully automatic planter. This is a labour/energy intensive
since the seed quantity is large. When planting is done manually high
labour/energy is required for planting and ridging. The seeds are
into the ridges using hand tools. When the crop is about 25 30 days old
intercultural implement like tripthali is run in the field followed by
ridges are opened up to expose the tubers using a digger or ridger or
using a khurpa. As compared to the other crops in potato at least one
+ planking ridging earthing up and harvesting wherever it is done
are the extra mechanical operations adding considerably to the cost of
cultivation and energy input.
operations in potato also involve considerable cost and energy. The
(about 25 40 tons/ha) has to be heaped in shade for skin suberization.
produce has to be sorted for removing cut cracked/damaged and diseased
grading and packing requiring considerable labour. Cutting
of the cultural operations directly results in reduced cost of potato
requires high fertilizer input. The recommendation for N P2O5 and K2O
northern plains ranged from 180 240 80 100 and 100 150 kg/ha
efficiency of utilization of the applied fertilizer is low in potato
frequent irrigations during early part of the crop shallow root system
growing season etc. Normally irrigation is applied at an interval of 8
initially while later on the interval increases to 12 15 days. The
irrigations at the initial stages of crop growth when the root system
fully developed leaches out a greater proportion of the nutrients out
root zone. This problem is aggravated by the shallow root system which
normally assumed to be about 60 cm only. The short growing period is
factor which increases the requirement of fertiliser since more
added at the time of planting so as to hasten the crop growth and
interception of the incident radiation.
weed free environment for optimum yield. Since potato tubers are
of weeds at the time of harvest makes harvesting difficult. Frequent
irrigations in the plains and rains in the hills and high nutrient
encourage luxuriant growth of weeds thus increasing the cost incurred
TOWARDS LOW INPUT TECHNOLOGY FOR POTATO PRODUCTION
of the consequences of high input cultivation steps are being taken to
the inputs. Saving can be made in labour seed tillage fertilizer and
inputs in potato crop perse as well as in the potato based cropping
shown that there is a possibility of practicing zero tillage/minimum
practices even in the case of potato. Results of experiments at Gwalior
that one harrowing followed by one planking did not affect tuber yield
fields which had green manure crop of synhemp buried in the kharif
Similarly in some situations the second earthing up can be done away
the full size ridge is made right at planting and where the ridges do
eroded due to irrigation. Weeds should be either negligible in these
or have to be controlled through herbicides. Saving in land preparation
also be effected in wheat following potato since the soil tilth is
improved at the time of harvesting of potato.
been made to save mechanical energy through use of low cost implements
reducing the labour/energy requirement. Some of the low cost implements
developed are peg type inter cultivator rotary peg type inter
blade type inter cultivator and cup type potato planter.
seed input cost many alternative seed production strategies have been
including true potato seed propagation through stem cuttings mini
However these technologies have not yet reached the stage of large
adoption. Hence these technologies cannot be evaluated for their effect
economics of potato production.
seed is another option to reduce the seed input cost. The use of small
with an adjustment in the planting geometry reduces the seed
use of small seeds has been found to economise the seed requirement by
50%. The availability of large quantities of small seed is a problem.
overcome this problem use of cut seed tubers has been studied. The
suggest that in ware crop where seed borne diseases as well as rotting
due to high temperature is not a problem cut seed can be used.
Treatment of the
seed with fungicides (2% solution of mancozeb) is recommended after
Large size tubers can also be effectively planted by increasing the
varieties giving high
yield at low fertilizer input can effect reduction in fertilizer input
technique has been developed to determine the fertilizer requirement
target yield. The technique consists of fitting the regression equation
determining the a b and c coefficients of the regression equation.
nutrient efficient varieties saving in fertilizer input could also be
through judicious choice of source of nutrient and method of
case of nitrogen urea is the cheapest source but it affects the growing
sprouts. Therefore other sources like ammonium sulphate calcium
nitrate etc. are recommended for potato but these are costlier than
Studies on economic and efficient use of urea have shown that
urea one day before planting mitigates the injurious effect. Similarly
of different methods of application have also been tried for making
safe use of
urea for potato. At Shillong application of 80 Kg N/ha through urea as
application top dressing and foliar application at tuber initiation in
2 1 1
ratio was as effective as 120 Kg N/ha thus economising about 40 Kg
Soaking of seed tubers in 3% urea for 1 hour has also been found to
10 Kg N/ha as well as give 26 q/ha more tuber yield. In the case of P
of seed tubers in 1.5% single super phosphate+ 0.5% urea solution along
suitable fungicide for 4 hours effected considerable saving in P
In addition biofertilizers e.g. Azotobacter and phosphorous
bacteria have also been found effective in reducing N and P requirement
cropping systems that utilise the residual nutrients efficiently can
reduce the fertilizer input. This aspect has been studied extensively
based cropping systems. Since potato is a shallow rooted short duration
with high nutrient input requirement it leaves considerable residues.
residues are effectively utilised by crops like wheat maize etc. grown
sequence following potato thus economising nutrient requirement of the
as a whole. The studies have shown that wheat following potato needs
N and no P and K the requirement of which is met out of the residues
In the case
potato sunflower and potato onion sequences the N requirement of
onion is largely met out of the residues after potato. Thus there is
effecting saving in fertiliser input of potato. However there is a
greater scope for saving in fertiliser input if seen from the cropping
perspective and can be fully exploited by judicious choice of sequences
on location season etc.
saving in water could be effected if efficient methods of irrigation
sprinkler or drip irrigation systems are adopted. These options being
cannot be advocated for low input situations. However a more scientific
scheduling technique can effect saving in water with minimum loss.
the crop at critical soil moisture deficit of 25 mm on medium textured
reduces the water requirement as well as losses at Jalandhar. Alternate
irrigation has also been found to economise water input. Almost 25 35%
saving has been found but yield decrease to the extent of about 10% has
been observed. Where labour is cheap and easily available mulching can
practiced. Paddy straw mulch has been found to save about 150 mm water.
Generally mulching can easily save 1 2 irrigations.
Many of the
cultural operations are complimentary to each other. Weed control is
operation which is benefited by many other cultural operations. Hot
cultivation recommended for control of soil borne pathogens also
problem of weeds. Similarly mulching practiced for water economy
weeds. As regards weed control perse economy can be achieved on system
due to the complimentarity of weed control in potato affecting the
in sequence. Studies showed that weed control in potato through
kg/ha and oxyfluorfen 0.2 kg/ha as pre emergence herbicides mitigated
problem in the succeeding wheat crop. In potato blackgram sequence weed
in potato through metribuzin 0.7 kg/ha minimised the problem of weeds
gram. Similarly in intercropping situations weed control in potato +
could be effected through use of metribuzin 0.5 kg/ha thus there is
considerable saving in input for weed control in the inter crop system
when both the crops are grown as sole crops.
Pests and diseases control
the most serious disease affecting the crop in the northern Gangetic
with the best option being growing resistant varieties. However where
it is not
feasible forecasting of the disease can help reduce fungicide input.
sprays are given and if the disease does not appear considerable loss
and chemicals occur. As regards most of the other pests and diseases
healthy seed and hot weather cultivation and adoption of appropriate
sequences minimizes the problem in most places in the ware crop.
practices developed to maximize potato production are highly input
However there is a considerable scope to reduce the inputs on a single
basis and much more possibility on cropping systems basis. So far the
technologies have been developed without considering the overall effect
input intensiveness. Therefore a combination of practices has to be
and developed for each situation since many of the technologies are
complimentary to each other. This would enable potato production not
fewer resources but also on a wider non traditional area.
REQUIREMENTS of Potato
nutrients which include
zinc iron manganese copper molybdenum boron and chlorine play a
in the growth and development of a plant. Even though these elements
in only minute quantities many soils do not supply them in sufficient
for healthy growth and optimum yield of potato.
of only NPK
fertilizers for growing high yielding potato varieties with increased
demands the decreasing availability of farmyard manure and intensive
agriculture have combined to increase the demands made on the soil in
its ability to supply micro nutrients to plants. It is becoming evident
the use of some of the micro nutrients it is not possible to get the
benefit of other inputs.
EFFECT OF MICRO NUTRIENTS ON GROWTH AND YIELD OF POTATO
constitutes about 75% of the dry weight of potato tubers. The amount of
accumulated is determined by the rate of photosynthesis translocation
photosynthates from leaves to tubers and their subsequent conversion to
The photosynthetic rate has been shown to increase by 72 and 80% in the
presence of 10 ppm of zinc and manganese respectively in Hoagland s
zinc has been shown to increase the incorporation of 14C from the
sucrose glucose and fructose into starch.
tuber yield with micro nutrient application can occur with an increase
number of tubers and size of tubers or both. Zinc iron boron and
have been reported to increase the tuber number of medium and large
the cost of small ones i.e. the total tuber number was not affected.
DIAGNOSIS OF MICRO NUTRIENT DEFICIENCIES IN SOILS AND PLANTS
first step for precise monitoring and efficient correction of micro
disorders in potato plants and soils. Several approaches have been used
diagnose the magnitude of micro nutrient deficiencies in potato plants
soils. They are discussed hereafter.
will appear whenever any one of the micro nutrients becomes severely
or fall below the marginal deficiency stage of development.
element develops its own
characteristic deficiency symptoms. Visual diagnosis of symptoms is
soon as the symptoms have appeared. The symptoms can not be easily
later on because they get modified by other environmental factors.
Zinc deficiency in
potato often known as fern leaf or little leaf appears on young
leaves. Deficient plants show severe stunting and bronzing or yellowing
foliage usually around the leaf margins starting from the tips (Fig 1).
Youngest leaves are cupped upwards and rolled to such an extent that
terminal growth resembles that of ferns. Leaves of affected plants are
and their upper inter nodes are shorter.
appears initially as yellowing of top young leaves. With time the
light yellow to nearly white. During the deficiency blade tips remain
fora longer time. Netted green veination is seen when traces of iron
absorbed and translocated along the veins for chlorophyll formation.
veinalion is actually a sign of iron recovery.
The first sign
of its deficiency is yellowing and slight cupping of younger leaves.
colour develops at the base of younger chlorotic leaves while
leaves show dark to black spots. With increased deficiency dark to
spotting develops between the veins with increased spotting appearing
larger veins and the mid rib. The symptoms of darkening and cupping of
in severity with time. Upon mild deficiency upper parts of the plants
somewhat chlorotic but do not develop dead spots.
An early sign of
its deficiency is the development of a uniform light green colour of
leaf blades similar to those of molybdenum manganese and iron
it is primarily seen as pronounced upward cupping and inward rolling of
young relatively large leaf blades. This is in sharp contrast to the
leaf blades of zinc deficiency.
causes the formation of a bushy plant with droopy leaves. Blades
upwards and are bordered by light brown tissue. Its deficiency like
the growing points. Immature center leaves become deformed and the
point dies. In case of mild boron deficiency slight upward curling of
margins of the older leaves is visible.
The symptoms of
its deficiency are marked
with reduction in growth and yield.
by the time micro
nutrient deficiency symptoms appear significant crop losses have
occurred. The critical nutrient concentration is a convenient reference
for assessing the nutrient status of a crop. The critical concentration
taken at the point where growth of the plants is 5 or 10% below the
point. The safe level is the nutrient concentration maintained
above the critical deficiency concentration for optimum potato
(Table 1). But care has to be exercised also to maintain the nutrient
the plant below the toxicity range. The toxicity limit of copper is
be 34 ppm in plant in acidic hill soil of Shimla region.
for total concentration of nutrients is generally recommended. However
analysis for total iron content often fails to explain iron chlorosis
plants. Iron in ferrous form has been found more useful to detect iron
has the major advantage over other diagnostic techniques as it
micro nutrient supplying capacity of a soil prior to planting of potato
Several chemical extractants have been used for estimating the plant
micro nutrient contents in different soils. The critical deficiency
DTPA. EDTA and ammonium acetate (pH 4.6) extractable zinc below which
response of potato to Zn application can be expected in acidic brown
of Shimla region are 0.55 1.70 and 1.50 ppm respectively.
critical deficiency limits of DTPA extractable Zn Fe and Cu in alluvial
of Jalandhar are 0.75 6.6 and 0.32 ppm respectively.
MICRO NUTRIENT DEFICIENCY IN POTATO GROWING AREAS
Soil is the
reservoir for supply of all the essential micronutrients required for
normal growth of potato crop. Thus information about the extent of
nutrient deficient potato growing areas is vital. Micro nutrients
soil in potato growing areas indicated that zinc is the most deficient
nutrient in potato growing soils followed by iron copper and manganese.
121 field experiments conducted in alluvial soil of Jalandhar (Punjab)
responded to Zn in 57% to Fe in 40% and to Cu in 38% fields with a mean
response of 21 21 and 24 q/ha respectively (Table 2).Table 2. Response
potato to Zn. Fe and Cu in different fields at Jalandhar.
RESPONSE OF POTATO TO MICRO NUTRIENTS
potato to micro nutrients differs with soil group. Zinc is the most
micro nutrient in almost all potato growing soils. Alluvial soils are
responsive to iron manganese boron and copper as compared to other
response of potato to applied micro nutrients depends on the magnitude
deficiency in the soil. Responses of potato are strikingly higher on
nutrient deficient soils than any other soils.
Factors affecting response of potato to micro nutrients
influence the magnitude of response to the applied micro nutrients. The
important among these are potato cultivars soil types and their
soil environment climate cultural practices and nutrient interactions.
Marked differences exist in potato varieties regarding their
micro nutrients. Cultivation of crop varieties less susceptible to a
nutrient stress can assist in economizing on the cost of alleviation of
deficiency. A fairly wide differential response of potato cultivars to
Zn Fe Mn
and B has been demonstrated under field conditions (Table 3).
and shoot parameters of
cultivars Identification of root and shoot parameters
better micro nutrient uptake efficiency can help to use the information
micro nutrient efficient varieties. An evaluation of zinc uptake
three potato cultivars grown in the same soil in pots showed that zinc
application significantly increased total dry matter accumulation
of cv. Kufri Chandramukhi by 41% and that of cv. Kufri Jyoti by 23% at
solution concentration of 0.03 ppin zinc but Zn application did not
matter accumulation (DMA) of cv. Kufri Badshah. This indicated That
Chandramukhi had least Zn efficiency followed by Kufri Jyoti and Kufri
The reason for low Zn uptake efficiency of Kufri Chandramukhi was its
root DMA ratio (3.6) than Kufri Badsliah (8.2) and Kufri Jyoti (7.1)
the zinc influx (Zn uptake rate per unit root length) was similar in
cultivars in the absence of Zn application.
MICRO NUTRIENTS AND QUALITY OF POTATO TUBERS
boron and molybdenum have been shown to increase ascorbic acid content
tubers. Zinc fertilization reduced the content of tyrosine
total phenols in tubers. The potato used for processing should contain
quantities of tyrosine and phenolic compounds as they are implicated in
discoloration which occurs in raw peeled potatoes due to oxidation of
and chlorogenic acid formation of ferric dihydric phenolic complexes
cooking in processed products. Molybdenum and boron application
starch content of tubers. Chloride reduced dry matter content in potato
It resulted in an inhibition of the activity of the hydrolytic enzymes
hence in feeble translocation of starch.
AMELIORATION OF MICRO NUTRIENT DEFICIENCIES
deficiency of a micro nutrient is detected it becomes imperative to
best fertilizer material and techniques to ameliorate the same at least
future cropping in the same soil.
Methods of micro nutrient application
main approaches to tackle micro nutrient disorders in potato.
approach consists of the
application of a micro nutrient carrier to the soil where large
quantity of a
fertilizer has to be applied to compensate the high fixation capacity
reversion of the nutrient elements to unavailable forms. However its
lasts for a few years depending upon the type of the soil and cropping
consists of foliar application of micro nutrients to each crop while
approach is of treating mother seed tubers with micro nutrient
Foliar spray during dry spell should be avoided between 11 a.m. and 3
prevent scorching of leaves. The optimum dose of different micro
presented in Table 4.
4. Doses of micronutrient
application for correction of their deficiency in potato
Time of application
application will be governed by micro nutrient content of seed tubers
growth stage at which particular micro nutrient is required and the
deficiency in the soil. Generally the micro nutrient content of seed
low and most of them are absorbed during the early growth thus it
fertilization with micro nutrients. Experiments carried out at Shimla
that spray application of Zn was superior to soil application and also
treatment in a soil that had marginal available zinc. But in the highly
deficient soil seed treatment with zinc salts proved to be the best.
delayed fertilization with zinc will be less effective in case the
undoubtedly has increased
production and labour efficiency. But concerns have been raised time
over its adverse effects on soil productivity and environment. These
erosion depletion of organic matter in soil low water availability
fertilizer and pesticide contamination of food and water bodies and
bio diversity. Dependence of modern agriculture on use of fossil based
as chemical fertilizers and pesticides/herbicides as well as farm
held responsible for the adverse effects. As a result there is a
interest in organic farming globally which holds sustainability of
resources and environment supreme along with natural taste and
quality of the produce. Thus organic farming for agricultural
favours maximum use of organic materials and discourages use of
inputs to ensure conservation of natural resources and healthy
Organic farming is still in its infancy in India and there is not much
done in this field on potato. However work has begun on this important
hence basics of organic farming are given in this chapter.
CONCEPT DEFINITION AND COMPONENTS
the twentieth century organic farming was the worldwide way of the
still is in vogue in many of the poorer and/or remote regions of the
farmers cannot afford the technological inputs of modern agriculture.
lower yield (5 15 percent) in organic farming than modern farming is an
accepted fact. However the net return on investment is usually higher
of low inputs and when environmental costs are taken into account the
farming is far superior on a long term basis. The profitability of
farming depends on the higher prices that its products command in the
place. Organic farming is not based exclusively on short term economics
also considers ecological concepts. Organic farming combines
techniques and stress conservation with modern technologies.
organic farming excludes the use of synthetic fertilizers pesticides
growth regulators. While it includes improved seed including
engineered crop strains minimum tillage practices manuring crops
organic materials (crop residues animal excreta nitrogen fixing legumes
and off farm organic wastes) and use of rock phosphate and gypsum. It
integrated pest management (IPM) that relies heavily on biological
principles and use of bio pesticides. Disease control through use of
dust extracts of toxic plants antibiotics derived from fermentation
allowed under organic farming. Weed control is effected through crop
and manual weeding. It relies on wind and solar energy instead of
energy. Use of biologically produced plant growth regulators is also
It emphasizes minimum use of any purchased inputs that too from outside
farm. The operative principle components of organic fanning are as
the production of crops
and livestock and management of farm resources so that they harmonies
than conflict with natural systems.
and development of
appropriate technologies based upon an understanding of biological
soil fertility for
optimum production through renewable resources.
crop diversification to
for optimum nutritional value
of staple food.
decentralized structures for
processing distribution and marketing of products.
relationships between those that work and live on the land.
a system which is
aesthetically pleasing for those working in this system and for those
it from the outside e.g.. It should enhance rather than scare the
which it forms a part.
the leaching of
nutrients through rotation with deep rooted crops.
avoidance of mould board
ploughing in favour of chisel ploughing.
nutrients into the rotation
onto a sod crop if possible to maximize uptake.
seasonal use of cover crops
in and around major cash crops.
Value of Organic Amendments and Soil Conditioners
The value of organic
amendments is assessed by the
amount of potentially available plant nutrients they contain. Usually
done in terms of their macro nutrient (N.P. and K) content. However
materials contain secondary and micro nutrients that contribute
to increased crop yields soil fertility and physical condition. Soil s
condition is improved through increased water infiltration water
capacity aeration and permeability soil aggregation rooting depth
soil crusting bulk density run off and erosion. Different organic
used along with their values are presented in the following section
organic manurers Well
decomposed farmyard manure (FYM) and compost made from animal excreta
litter are bulky in nature and supply small amounts of plant nutrients
classified as bulky organic manures. They are applied 15 30 t/ha.
nutrient content of different bulky manures is given in Table 1.
1. Average nutrient content
of bulky organic manures
SUSTAINABLE INTEGRATED NUTRIENT MANAGEMENT
nutrient management (INM) is the maintenance of soil fertility and
nutrient supply to an optimum level for sustaining the desired
through optimization of the benefits from fertilizers organic manures
manures bio fertilizer non conventional sources and crop residues.
nutrient management aims at maximization of the use efficiency and
of the avoidable losses of nutrients from all the sources such that
objective of maximization of crop yields sustenance of soil water and
quality and improvement of socio economic conditions of farming
accomplished. It recommends conjoint application of chemical fertilizer
manures and bio fertilizer in addition to inclusion of legumes in
systems and incorporation of on and off farm generated crop residues to
constitute an efficient integrated nutrient management strategy. Most
INM components are discussed briefly hereunder
Chemical fertilizers have played a major role in enhancing the food
But the average consumption figure of 86.8 kg NPK/ha in India
25% of the recommended rates. In a state like Arunachal Pradesh where
it is as
low as 1.9 kg/ha there is a scope of enhancing the use of NPK on the
agricultural lands. The sustainable agriculture means application of
maximizing but environmentally safe fertilizer dosages by resorting to
splits in sandy soils especially for higher N rates by using slow
manures They are
valuable by products of farming or allied industries and derived from
animal sources. Bulky and concentrated organic manures have been
an earlier section. Depending upon availability they can substitute up
mineral fertilizer and 100% Pand K at appropriate dosage to potato
crop. In the
dry sandy soils during limited water availability organics play major
beneficial role in improving soil structure conserving soil moisture
enhanced aggregation and moderating the extremities in soil
benefit of this approach can be utilized in early crop of potato when
high soil temperature the tuber yields are normally very low.
fertilizers. In INM bio
fertilizer are used only to supplement nutrients in combination with
fertilizers and organic manures. Various bio fertilizer have been
an earlier section.
manuring. The green
manuring has already been discussed earlier. Role of green manuring in
to supplement nutrients in combination with chemical fertilizers and to
physical condition of the soil. Green manuring usually does not help
reduce N fertilizer needs of potato yet for fixed yield targets some
nitrogen is possible because tuber yield level is raised by green
Green manuring helps achieve 30 50% higher produce of tubers of uniform
and size and superior quality.
Serological Diagnosis of Potato Viruses
An early and accurate
diagnosis of the viruses is
essential for effective management of the viral diseases in potato seed
Control of plant virus diseases relies primarily on preventing the
establishment development and disposal of the causal viruses. Plant
generally identified by the visual symptoms induced in the host and/or
indicator plants particle morphology mode of transmission serological
properties and nucleic acid sequences.
viruses and allied pathogens in any given environment are limited on
Virus disease symptoms may be checked biologically on a set of
(Table 1) by mechanical sap and or aphid/graft inoculations. Each
(potato) leaf/tuber must be tested separately. For bioassay leaf
be obtained from two positions i.e. one from top and second from the
Ideally two unrelated tests must be done for each sample.
1. Plant species reaction
to important potato viruses and viraids. L local symptoms (L) haphazard
S. systemic symptoms
types of indicator hosts viz systemic (Fig. la) and local lesion hosts.
latter are effective because they are highly sensitive quick in
show clear reactions such as chlorotic or necrotic spots. Careful
test plants is important because not all strains or ecotypes of any
may be equally susceptible and responsive. Unfortunately not many
be routinely detected by using such test plants. There is also a great
variation(s) in their reaction to the virus their isolates or strains
Gomphrena globosa does not give local lesions for XHB strain of PVX C.
reacts systemically to PVS strain or depending on external factors such
inoculation method load of inoculum conditions for growing test plants.
Providing moderate temperature (18 24° C). high humidity (>80%)