Potato Seed Production

Potato is a vegetatively propagated crop; hence the crop vigour and yield largely depends upon the quality of seed material obtained. Usually the farmers are in practice of purchasing smaller tubers from cold stores without bothering much about quality as it is cheaper. But if the seed tubers are disease affected then the yield is found to be very poor. The practice is very obvious because cost of seed itself becomes more than half of the total cost of cultivation and non availability of seed at sowing time compels the farmers to purchase the tubers from the nearest convenient place. Problems of seed can be solved by adopting proper seed plot technique on the plains, also as the seed stock produced in the hills will not be sufficient for entire plain area, and moreover, the seed crop grown in hills is harvested during July-August and remains dormant during the period it is planted on the plains. Therefore, it is essential to know about seed plot technique and to adopt it carefully. Following steps must be taken for raising healthy seed stock on the plains.

1. The seed should be purchased from a reliable source like National Seed Corporation, State Seed Farms, Seed Department of Agricultural Research Stations or Agricultural Universities, etc. so that it is true to the type and free from seed-borne diseases.
2. To maintain purity of the crop from disease pathogens and other problems, an isolation distance of at least 30 metres should be maintained between a seed crop and a ware crop of potato in the neighbourhood.
3. The seed crop of potato should be planted in the first week of October in Punjab, second week of October in Rajasthan, Haryana, Delhi and in third week of October in eastern U.P. and Bihar.
4. An application of Thimet 10G should be done at the rate of 15 kg per hectare before last tilling of the field so that the chemical is well mixed in the soil. It controls the whitefly and jassids which are potential vectors of virus in potato crop.
5. Always pre-sprouted and healthy tubers of 4-6 cm diameter should be used for planting. These tubers should have multiple sprouts on them. Freshly harvested tubers obtained from hills need treatment for breaking dormancy before they are planted on plains.
6. While preparing the seed bed all the weeds and crop stubbles must be picked up and thrown out of the field. For an efficient control of weeds from the potato fields, a pre-emergence application of Simazine at 0.5 kg/ha rate or Tok E-25 at 2 litres /ha rate with or without Stam F-34 at 2 litres per ha rate should be done. Post planting cultural operations except earthing should be avoided in order to minimize the spread of mechanically transmitted viruses.
7. The seed plot must be examined from time to time and roguing of off-type and plants showing symptoms of mottling, mosaic, veinal necrosis, crinkle and rolling of leaves must be done. The seed plot must be examined at least twice -first soon after full emergence and second 20 days later or before the plants in adjacent rows touch one another.
8. The crop should be sprayed with Dithane M-45 or Dithane Z- 78 at fortnightly intervals starting from middle of December till killing of haulms.
9. Irrigation should be stopped from about 10-15 days before removal or killing of potato haulms.
10. The haulms should be cut and removed or killed by spraying of Paraquat, a total plant killer, in the crop for the purpose of prevention of viral infiltration. It should be done towards the end of December in Punjab, western V.P, and a week or so later in Bihar and parts of V.P. when aphid build up reaches the critical number (20 aphids per 100 leaves) and chances for viral infection become very high.
11. The re-growth of stump must be removed soon after they come out. The crop should not be irrigated after haulms are removed. Tubers should be lifted about 10-15 days after killing of haulms as by this time the skin of the tubers becomes hard and chances for skin bruising are minimized during lifting or transporting from the field.
12. All the injured or cut tubers must be sorted out and rest of them should be heaped in a cool, aerated and shady place for about 10 days so that tuber stem is thoroughly cured. The skin cured tubers should now be graded and bagged.
13. Before bagging the seed tubers must be treated with 0.5% solution of Agallol-3 for 3-5 minutes to protect them from surface borne diseases during storage period.
14. Tagging must be done by writing all the information about that particular variety. Usually three colours for tags are used to indicate different grades like red-blue tags for special or large tubers, dark-blue for phool or medium tubers and light blue for ration or small tubers.
15. If the seed is grown for marketing purposes than it must also be certified by proper agency and sealed before they are dispatched for storage.
16. If possible, the seed tubers should be stored separately in the store to avoid infection and mixing of bags.