Agro-techniques for raising potato crop from True Potato Seed (TPS)

Dr. Manoj Kumar SMS (Agronomy), KVK, Longleng

  TPS Technology: An Alternative to seed tuber Potato is a high input crop and is traditionally cultivated through seed tubers. About 40-50 % of the total cost of production is needed to procure seed tubers. Constraints of poor availability of high quality seed tubers in adequate quantity and at reasonable cost, inadequate availability of important inputs like fertilizers, pesticides etc., coupled with lack of knowledge of the improved technologies for potato production and inadequate facilities for storing seed potatoes in north eastern states are the major reasons responsible for poor potato productivity. It is in this context that TPS (True Potato Seed) technology assumes potential as an alternative method of potato production that is scientifically sound, technically feasible, economically viable, and eco friendly to generate low cost and high quality planting material for enhancing the productivity, production and reducing the cost of potato cultivation. TPS, besides giving an almost disease free potato crop, is also cost effective. Being very small in size, TPS can be stored and transported easily with almost no cost involved in the same. In addition, only 50 gms TPS is required for sowing in about 350-375 sq. mt. area for producing seedling tubers enough for planting one hectare next year which in case of potato production through seed tubers would require 2-2.5 ton/ha. Hence, it significantly reduces the total cost of cultivation. In addition, the obtained produce of TPS crop could also be utilized as the quality seed stock for planting in subsequent season for mitigating the problem of poor availability of quality seed material in this region.   Advantages of TPS technology

a. Provides disease free planting material with no investment on seed health testing

b. Low cost planting material (Rs. 4500/ha as against Rs. 30,000 - 40, 000/ha for seed tuber)

c. Easy to store and transport(Seed rate of TPS-150 g/ha and seed tuber-2.0-2.5 t/ha)

d. Saving seed tuber for consumption

e. Provides better disease resistance

f. Production sites not restricted

g. Saves land needed for tuber seed production

    Methods of tuber production through TPS

i. Transplanting TPS derived seedlings

ii. Planting seedling tubers raised from TPS

    Preparation of nursery bed for raising seedlings

1. Mark the nursery bed area keeping its breadth as 1m and length as per convenience. Beds may be separated by 80 cm wide pathway.

2. Soil for nursery bed should be taken from a depth of 20-25 cm to avoid weeds and soil borne diseases. Mix the soil in 1:1 proportion with fully rotten FYM or compost. Add the basal dose of N, P and K at the rate of 13 gm urea, 75 gm SSP and 10gm MOP per square meter.

3. Mix Thimet10G granules at the final nursery preparation stage to keep away ants and other insect pests.

4. Cover the top of nursery beds with half-inch thick layer of screened FYM.

5. Make proper arrangements to protect nursery beds from direct rain and sunlight.

In areas where brown rot is endemic, seedbeds should be raised by about 25-30 cm above the field level so that the seedlings do not root in the native infested soil.     Sowing of TPS in nursery beds:

1. About 50 gms TPS and around 375 square meter nursery bed area are required for producing enough seedling tubers for planting one hectare area in the next year. Soak the TPS in water for 24 hours, remove from water, again soak in 0.2% Diathane M-45 solution for 15 minutes. Then air-dry the seed in shade for 2 hours.

2. Mix the dried TPS with dry soil or sand or fine FYM. Spread the mixture evenly on nursery bed at a rate of 1-2 gms of TPS per meter square and cover it with half inch of the layer of FYM dust.

3. Irrigate the nursery bed using a sprayer ensuring that the soil is kept moist without any run off water.

4. Provide shade over the nursery bed from 10 AM to 5 PM if day temperature is above 300C for next 15 days after sowing. Leaf or straw mulch or some other protection can be used to protect bed from direct sun light and rain. This hastens the germination by conserving moisture and reducing soil temperature.

5. Keep constant vigil of nursery bed to see requirements of seedlings. Irrigate the seedbeds as per the requirement to keep the bed moist.

6. Keep the nursery bed open during day and night when germination starts.

7. Foliar spray of 0.1% urea (one gram urea in 1 liter water) after 2-leaf stage is beneficial for quick growth and vigor of seedling. Seedlings are ready for transplanting in 30 days of sowing when it attains a height of 10-12 cm. Seedling must be transplanted before stolon initiation to avoid yield losses.

8. Best time for raising TPS nursery is in the month of March (For summer crop) and July-August (for autumn crop)

    Transplanting of Seedlings in the field Under Irrigated Conditions:

1. Transplant seedling in field during afternoon only, to reduce damage due to water stress.

2. Broad cast 60 Kg N/ha (130 kg urea) and full-recommended dose of P (750 kg SSP) and K (100 kg MOP) at the time of final land preparation for seedling transplants.

3. If FYM application is done, first apply fertilizer mixture in furrows and then cover with FYM.

4. Furrows should be 4-5 inches deep at 40cms apart and prepare irrigation channels as practiced in the region.

5. Irrigate the furrows of two adjacent beds simultaneously just before transplanting. Take care to fill only half of the furrow with water leaving the top 8-10 cm of ridge dry.

6. Transplant the seedlings in two beds simultaneously (on both sides of irrigation channel) in north facing ridges by pushing seedling root in soft mud 10 cm apart and allow water to go in first furrow in 2nd bed. Then transplant seedling in first furrow of 2nd bed and allow the water to go in 2nd furrow of first bed. Thus, transplant seedlings in furrows of 1st and 2nd bed alternatively. Interplant spacing should not exceed 10cm for higher yield.

7. Spray 0.2% Dursban/Chlorpyriphos 20EC (25 ml in 10 liters of water) or Endosulfan 35EC (20 ml in 10 liters of water) on fourth day to protect seedlings from cutworms.

8. Irrigate the furrows every 3rd or 4th day till the seedlings get established. Frequency of irrigation can thereafter be reduced to once in 8-10 days as per crop need and according to the weather condition.

9. Do weeding after 25-30 days of transplanting depending upon the intensity of weeds and perform the earthing up operation and also apply ¼th dose of recommended Nitrogen i.e., 30 Kg N/ha (urea 65 kg/ha). Care should be taken to cover maximum nodes with soil leaving the top 5-6 leaves open in the air. Final dose of N (30Kg/ha) is applied at 2nd earthing up which is performed after 25-30days of first earthing up operation

10. Do all the subsequent operations including plant protection measures as per the standard potato cultivation practices of the region.

11. Dehaulm the crop 10-15 days prior to harvest and allow the skin to harden.

12. Harvest the crop after 110-120 days. Produce should be graded and small to medium sized tuber should be retained as the planting material for the subsequent season. Large size tuber, however, could be used for table purpose.

    Plant protection measures

a. Control of insect pests: Occasionally cutworms and defoliators damage the crop particularly during the dry season. If cut worm appear in significant numbers drench the ridges with Chlorpyrifos (Dursban) 20 EC @ 2.5/ha in 800-1000 liters water. For controlling defoliators and leaf eating caterpillars, spray the crop with endosulfan @ 1.5 a/ha or with carbaryl @ 2.5 kg/ha in 1000-1200 liters water. If needed, additional sprays should be given. Chlorinated hydrocarbon insecticides (e.g. Heptachlor, Aldrin) dust should not be applied because of residual toxicity problems. Potato tuber moth (PTM) damages the potato both in the field and in the store. To control tuber moth in the standing crop, spray the crop with carbaryl @ 2.5 kg/ha in 1000-1200 liters water. In Country stores, the tubers should be covered with dried and chopped leaves of Lantana or Eucalyptus plant for protecting them from the attack of potato tuber moth.

b. Control of fungal and bacterial diseases: In the North- eastern hill region, fungal diseases such as late blight,P homa and early blight damage the potato severely. To control them, periodic sprays with 0.2% solution of mancozeb at 8-10 days interval should be given from mid May. While spraying, it should be ensured that the lower surface of the foliage is thoroughly drenched with the fungicide solution particularly when sprayings are done during rainy days. Brown rot is another important disease in North-eastern hill region. Infected seed tubers and soil are the primary sources of infection carrying the disease from one season to another. It is, therefore, important that healthy seed, free from brown rot infection, is used for planting. Severity of the disease can be reduced by planting the crop between the second week of February to first week of March and harvesting before first week of June. Apply bleaching powder 12 kg/ha mixed with fertilizer at planting. Incidence of this disease can also be reduced by adopting crop rotation with maize. Soil burning is also recommended for sick soils infected with this disease.

  Haulms killing: Irrigation is stopped 10 days before haulms killing in the valley / low hills. Haulms should be killed with gramaxone @ 3 1/ha by 15-20th August in hills and 25th December to 15th January in valley depending upon the date of planting in the region. Crop should get a duration of 80-90 days before dehaulming. Exposed tubers should be covered with soil immediately after haulms killing. Crop should be harvested 10-15 days after dehaulming. This will allow hardening of tuber skin.   Harvesting: Crop is harvested 10-15 days after haulms cutting for allowing hardening of skin of potato tubers to prevent disease infection through skin. Harvesting should be carried out on bright sunny days. Tubers may be kept for 15 days in the shade for further hardening of the skin. Remove the cut/crack/bruised and damaged tubers.   Grading of produce: Grading of produce is important because of marketing purpose and also for giving uniformity to the next emerging crop. Produce is graded into four grades i.e. large (>150 in hills), medium (80-125 g), seed size (40-80 g) and small (20-40 g).   Storage of produce: Storage of potato tubers should be done only after proper drying. Potato can be stored in plastic or in gunny bags of 50 or 80 kg capacity. Bags are kept in the cold stores at 2-40C in the plains while they are stacked in the country stores in the hilly region. It is important to turn the bags once in every two months in the country/cold stores. Store should be cleaned and sprayed with insecticides before storing the seed tubers. If storing the potato seed in country store, it is important to cover the potato with dry sand and apply 1 % malathion dust to damage from tuber moth. Leaves of lantana or eucalyptus after chopping and drying may be spread on the floor as well as on the top of the heap of the potato. Layer must be 2-3 cm thick.   Tuber may also be stored spreading them in a room with diffused light condition, preferably in single layer on bamboo platforms. Sprouts will come out but will not grow much if some light is there and the tubers will be suitable for planting in the next crop. Seed should be also stored in wooden trays of convenient sizes or baskets in well-ventilated rooms.