Everything you need to learn about potato cultivation, harvest and growth.
Introduction to Potato:
Potato is one of the most important food crops of the world. It is believed to be a native of South America and is now grown in many countries, the leading of them being the USSR, Poland, West Germany, France, the USA, the United Kingdom, Czechoslovakia and China. The plant was introduced into Europe by Spanish explorers sometime between 1531 and 1535 AD and it reached England and Ireland by 1586.
Potato was brought to India sometime in the 17th century. The tubers, which are the edible portions of the plant, are modified stems and they are consumed in India mainly as a vegetable. The per capita annual consumption of potato in India is very low and is roughly about 4.5 kg, while in certain western countries; the amount is very much higher.
In India, the crop is grown mainly in UP, Bihar, West Bengal, Assam, Orissa, HP, MP, Punjab, TN, Karnataka and Maharashtra and covers an area of about 7,50,000 hectares, the annual production being 10 million tonnes. About 75% of the crop is grown in the plains of north India during winter and 15% in the hills during spring and summer. In the Nilgiri hills, potato is cultivated throughout the year. Potato tubers are rich in carbohydrates and contain about 18% starch, 2% proteins, and 9% fat, in addition to 78% water.
Potato (Solanum tuberosum L.) belongs to family Solanaceae. The plant is an annual herb, vegetatively reproduced by tubers, which are underground stems. Stem erect in the early stage, but becomes spreading and prostrate later on. Leaves are alternate and pinnately compound.
Flowers are white, purple or yellow coloured, borne on racemose inflorescence. Sepals are connate in 5-6 lobed calyxes. Petals are usually 5, tubular and united. Stamens are 5, epipetalous. Carpels 2, connate in a 2-4 celled ovary. Style is columnar. Stigma is small, bilobed. Fruit a small globose berry with many seeds.
Climate and Soil Required for Potato Cultivation:
Potato can be cultivated under different climatic conditions. It does best in cool moist climate. A temperature range of 20°—30° C is quite suitable for it. The plant grows well under long-day conditions.
The crop is cultivated under a wide range of soil types, ranging from sandy loam to clay soils. Good yields of potato tuber may be obtained in fertile heavy soils. Properly drained soils are always preferred. In order to control potato scab disease, the crop should be grown in soil with pH between 4.8 and 5.4. Very good yields have, however, been obtained from crops grown in soil with pH varying from 5.0 to 7.0.
Cultivation of Potato:
The sowing time of potato in the plains of northern India extends from the middle of September to the beginning of January. Two successive crops are sometimes raised on the same land. In the hilly areas of the North, sowing of the crop is done in March- April. In the Nilgiri Hills in the South, as many as three crops are raised in succession, in April, August and January.
A well-prepared seedbed is required for the potato crop. The land is thoroughly ploughed to pulverize the soil and then leveled. The field operations have to be finished in time so that there is optimum moisture in the soil at the planting time. As waterlogged conditions and wet soils affect the crop adversely, arrangements should be made for drainage and aeration.
Potato tubers are planted either whole or after cutting them into pieces. Both these systems are satisfactory so long as the tubers are disease-free. When planted whole, the tubers should be small. On the other hand, when large tubers are used, they should be cut into pieces. Each piece should have at least one eye. The weight of seed required per hectare varies from 800 to 1500 kg, according to the size of seed tuber.
Potato tubers have a rest period, which varies from four to ten weeks when they are stored at 21°C. The dormancy may be shortened by various methods. Certain chemicals, like thio-urea, chlorohydrin or potassium thio-cynate or ethylene gas may be used for the purpose.
Four methods of planting are adopted, namely, ‘ridge-method’, ‘furrow-method’, ‘flat method’ and ‘double furrow method’. In the first method, ridges are made at a distance of 45- 60 cm and tubers are planted on them; in the second, furrows are made with narrow spades and the planting of tubers is done on the side of the ridges; alternatively, tubers are planted in the furrows and it is followed by ridging; in the third method, tubers are planted in flat beds and ridges are made after sprouting of the tuber; in the last method, which is popular in Punjab, shallow furrows about 5 cm deep are made about 75 cm apart, in which manure is applied; tubers are then planted on both sides of each furrow.
Manuring and Fertilization:
Farmyard manure at the rate of 30 tonnes per hectare should be incorporated into the soil 3-4 weeks before planting. In addition, 120 kg of N, 100 kg of P2O5 and 70 kg of K2O per hectare should be applied, of which 80 kg of N and the full dose of the other two may be applied at planting time and the remaining quantity of N as top dressing at the time of first earthing-up.
Irrigation:
The crop requires a good deal of water, the application of which should be well spread throughout the growth period. Irrigation should start two weeks after the emergence of the plant. Light irrigations are given in the early stages and heavier in the late stages. The frequency of irrigation depends on various factors, like the nature of the soil, seasonal rainfall, stage of the crop and fertilizers used. Usually, 6 irrigations are considered sufficient.
Earthing should be done in the plains when the plants are 15 to 22.5 cm high. If considered necessary, a second earthing is done after two weeks of the first one.
For controlling weeds, application of chemicals, Linurion or Simazine, at the rate of 0.5 kg per hectare, as a pre-emergence spray, has been found effective.
Harvesting and Yield:
The crop takes three months or so to mature. In the plains, the October-sown crop is generally harvested in February. In the hills, harvesting of the main crop should not be done in the rainy season. The colour of leaves changes when the potato reaches maturity. Tubers are dug up with the help of a kodali or spade. The average yield of tubers varies from 20 to 30 tonnes per hectare.
Storage:
Storage of potato tubers depends upon the use to which they are to be put after the storing period. Most of the varieties of potato can be stored for a long time, for 6 months or even more, without sprouting, if the temperature does not exceed 4.4°C. Storing potato in cold stores, at a temperature between 2.2°C, and 3.3°C at 75 to 80% relative humidity, is regarded the best method of storage.
Uses of Potato:
The potato tubers are used mainly as vegetable. In many western countries they make a universal table food. During the two world wars, the serious food problem in UK and Germany was solved to a great extent by potato. Small tubers are commonly used for the production of starch and industrial alcohol. The tubers are sometimes fed to livestock. Potato chips made from fresh potato tubers are very much liked by many people.
Varieties of Potato:
Some of the improved varieties now under cultivation in the country are:
Certain old varieties, which are sometimes cultivated, are:
Satha, Gola, Phulwa, Up-to- date, Darjeeling Red Round, Craig’s Defiance, Great Scot and President.
Diseases of Potato:
The important diseases of potato are:
(i) Early blight caused by Alternaria solani, which can be controlled by spraying the crop with 4: 4: 50 Bordeaux mixture or with Zineb @ 2 kg/1,025 litres per hectare.
(ii) Late blight caused by Phytophthora infestans, which can be controlled by spraying the crop with 1% Bordeaux mixture or with Zineb @ 2 kg/1,025 litres per hectare.
(iii) Leaf roll caused by virus, which can be controlled by roguing out affected plants and carrying out heat treatment of tubers at 40°C for 2 hours each day for 6 weeks.
(iv) Mosaic caused by virus, which can be controlled by roguing out affected plants and by planting certified, disease-free seed.
(v) Bacterial wilt or brown rot caused by Pseudomonas solanacearum, which can be controlled by crop rotation and by using clean, disease-free seed.
(vi) Charcoal rot caused by Macrophomina phaseoli, which can be controlled by early harvesting, treating the tubers from the affected crop with Agallol or Aretan and growing resistant varieties.
(vii) Wart caused by Synchytrium endobioticum, which can be controlled by growing resistant varieties.
(viii) Black heart, a physiological disease caused due to unfavorable conditions during storage and transit, which can be controlled by providing proper storage conditions with adequate ventilation.
(ix) Scab caused by Streptomyces scabies, which may be controlled by treating the seed-tubers with mercuric chloride and by treatment of soil with Brassicol.
(x) Root knot nematode (Meloidogyne incognita and M. javanica), which can be controlled by applying D.D. @ 400 kg per hectare or EDB @ 100 kg per hectare or D.B.C.P at 10 kg per hectare to the soil one month before planting.
Disease resistance occupies a very important place in potato breeding in India and some valuable results have already been achieved in this respect. A few of the improved varieties named above under “varieties” possess resistance to one or more of the important diseases.
Kufri Sindhuri and Kufri Lalima are moderately resistant and Kufri Chamatkar is resistant to early blight disease; Kufri Jyoti is moderately resistant to early blight and resistant to late blight and wart; Kufri Badshah is resistant to early and late blight and also to virus ‘X’; Kufri Sherpa is moderately resistant to early blight and virus ‘Y’, resistant to late blight (foliage and tubers) and immune to wart; and Kufri Swarna is resistant to early and late blight and highly resistant to cyst nematode.
Insect Pests of Potato:
The important insect pests of potato are:
(i) Cut worms (Agrotis ipsilon, A flammatra), which can be controlled by dusting plants with 4% Carbaryl and by mixing 5% Aldrin or Chlordane or Heptachlor dust with the soil around the plants.
(ii) Leaf eating beetles (Epilachna vigintiocto punctata), which can be controlled by collecting and destroying infested leaves along with insects in the initial stages and spraying 0.1% Carbaryl or 0.05% Malathion or Dichlorvos.
(iii) Tuber moth (Phthorimoea operculella), which can be controlled by cold storage or by keeping tubers covered with earth while in the field, and, in godowns, by fumigating the infested tubers with methyl bromide.
(iv) Aphids (Aphis gossypii, Myzus persicae), which can be controlled by spraying 0.1% Malthion or 0.05% Dichlorvos.
(v) White grubs (Xylotrupes gideon, Lachnosterna longipennis, Anomala spp), which can be controlled by thoroughly mixing 5% Aldrin or Heptachlor dust with the soil at the time of planting.
(vi) Jassids (Amrasca biguttula biguttula, Empoasca kerrimotti), which can be controlled by spraying 0.1% Malathion or 0.05% Dichlorvos.