SEED PRODUCTION

SEED PRODUCTION

Following procedures should be followed for seed production:
  • Potato plant is very sensitive to ecological factors such as temperature, rainfall, photo period etc.
  • Optimum night temperature range from 15-20oC in pre-tuber initiation phase and 15oC in the post tuber initiation stage is required.
  • The application of farmyard manure and gypsum/pyrites is needed for soils with pH more than 8.5 and conductivity less than 1 mmhos/cm2 to make it suitable for potato production.
  • Pre sprouting
    • Pre sprouting of seed tubers before planting seed crop is essential.
    • It ensures multiple, stout and healthy sprouts.
    • It helps in quick emergence and uniform stand and early maturity of the crop.
    • It also facilitates higher multiplication rate, more number of tubers and large production of seed sized tubers and pre-sprouting.
  • Seed should be taken out from the cold store, 10-15 days before planting in the plains.
  • The time of planting for seed crop in the plains varies with agro-climatic conditions of the regions.
  • The optimum time of planting for western-central and eastern Indo-Gangetic plains is first week of October, second to third week of October and last week of October to first week of November, respectively.
  • In the plains, optimum yield of seed potatoes can be obtained by green manuring of Sunhemp (Crotalaria juncea) or Dhaincha (Sesbania aculeata).
  • The Dhaincha crop of 45-55 days adds 250-300 quintals of green biomass/ha.
  • If green manuring is not done, 200-250 quintals of farmyard manure/ha is applied to improve the fertility and physical condition of the soil.
  • Nitrogen, phosphorous and potash requirements should be based on soil test of the field.
  • In general, a basal dose of 75 kg nitrogen, 60-80 kg phosphorous and 100-120 kg potash/ha may be applied at planting.
  • Traditionally, seed of relatively small size (25-30g) is used for planting both in the hills and plains because of its better keeping quality, delayed sprouting in ordinary stores and lower seed rate.
  • It has been observed the planting of 40 g seed tubers at 50 cm inter row and 20 cm intra-row spacing.
  • It has been found best for seed production.
  • Seed crop of potato can be planted with a tractor drawn potato planter or implements for all the operation viz. opening furrows, application of fertilizers, placement of tubers, ridging and spray of insecticides.
  • Another method is that first ridges are formed after application of fertilizer and insecticides and then tubers are dibbled with Khurpa (a narrow blade tool) 5-7cm deep in the ridges manually.
  • Care should be taken that tubers should not come in direct contact with the fertilizers and should remain 4-5 cm above or side of fertilizer done.
  • Intercultural operations and weeding should commence at about 20-25 days after planting when plants attain height of about 10-15cm.
  • Weeds compete for moisture and nutrients with potato crop mainly at two times during potato cultivation first before earthing up and second towards the maturity and harvesting of crop. Timely weed control either chemically or manually is essential otherwise potato yield is affected.
  • During early stages of growth of potato plants, weeds may be controlled by a spray of paraquat dichloride (gramaxone @ 2.5 Kg a i/ha dissolved in 1000 l of water) at about 5 per cent emergence of plants.
  • Sencor (metribuzin)@1.0 kg/ha as pre-emergence are effective herbicides.
  • In the plains, potatoes are grown in winter season when seasonal rainfall is not sufficient to meet the entire water requirement of crop.
  • Hence, frequent and light irrigation to potato crop at low moisture tension, except in river bed cultivation in Gujarat is essential for raising a successful seed crop.
  • Water stress after planting delays emergence, whereas, water stress after emergence reduces the internodal length of stem and the size of leaflets.
  • Tuber initiation stage is considered as critical stage for water stress, which reduces the tuber number and yield.
  • Aphid, Myzus persicae is the most important virus vector for potato crop.
  • Amongst potato viruses, leaf roll and virus Y are very serious, as due to their infection tuber yield is reported to be reduced by 25-80 per cent.
  • The yield of plants infected with contageous viruses (Y, A and M) and leaf roll, is reduced by 10-15, 50-75 and 60-75 per cent, respectively.
  • In the plains, three field inspections for roguing of mosaics, leaf roll and off-type plants are recommended.
  • The first inspection and rouging should be done after emergence of plants and before earthing up, second at 40-50 days after planting and third just before the dehaulming to ensure better seed quality.
  • Phorate 10G @10kg/ha should be applied at planting to control jassids, leaf hoppers and white flies in order to check the spread of vector transmitted viruses.
  • An additional quantity of phorate 10G @7.5kg/ha should be applied at the time of earthing up to prevent the infection of aphid vector.
  • For early blight and late blight, it is better, if one prophylactic spray with Dithane M-45@ 2kg/ha is given.
  • This should be repeated at an interval of 10-14 days, depending upon the weather conditions.
  • Harvesting may be done by either tractor or bullock drawn digger or manually with the help of a spade or Khurpa.
  • Harvesting of seed crop in the Indo-Gangetic plains should be completed by 15th February and should not be delayed beyond the end of February to avoid tuber rotting due to soft rot and charcoal rot.
  • Harvesting in the plains should be undertaken 10-15 days and in the hills about 15-20 days after dehaulming, when skin is hard enough to withstand handling operation.
  • After harvesting, potato tubers are required to be kept in heaps for about 15 days for curing of skin and shedding of soil.
  • For better return in the market and to adjust seed rate according to size during planting, proper grading is essential.
  • Grading of seed potatoes in four grades viz. small below 25g (25 mm), medium 25-60g (25-35 mm), large 60-100g (35-50 mm) and extra above 100 g (above 50 mm) tubers are important.
  • Treated tubers should be dried in shade.
  • Seed potatoes are packed in gunny bags of 80 kg each in the western and central plains, whereas in 50 kg each in the eastern areas of the country.
  • The temperature in the cold should be maintained at 2-4oC during storage.
  • The yield of seed crop ranges from 200 to 250 q/ha depending upon the duration of the crop.
Last modified: Sunday, 17 June 2012, 6:44 AM