TPS & SPT of Potato
True potato seed (TPS) is a matured ovule of potato resulting from sexual fertilization. It is entirely a new technique of seed production in potato which can replace the tubers using as seed instead for using as food. A single plant may produce 50-100 berries and single berry contains about 150-200 seeds. TPS is mainly used to develop new potato cultivars and now gaining popularity to raise the commercial crops. About 100-150 grams of seed is required to raise the crop in 1 hector of land. The non-availability of good quality seed tuber, high seed cost, virus infiltration in seed tubers causing degeneration of seed stocks & problem of long-distance transport of seeds from seed producing areas have to led to the development of TPS technology of crop production.
The mentioned two methods below have been successfully employed to raise crop using TPS.
- Raising of crops from transplanted seedlings
- Raising of the crops from seedlings tubers
Raising of crops from transplanted seedlings:
TPS has to be sown in nursery beds to produce seedlings. The best substrate for nursery beds is a mixture of 1:1 FYM & soil. Soak the seeds in water for 24 hours before sowing. TPS germinates well when night temperature drops to about 20 degree Celsius in the plains & shade is provided over nursery bed areas during day time. In plains the best sowing time is October.
The seedlings raised in nursery can either be transplanted in field to produce a ware/seed crop or alternatively allowed to tuberize in the nursery beds to produce small seedling tubers which can be used for field planting next year. The methods of raising the crop using small seedlings tubers produce in nursery bed is successful in all the potato growing regions of the country. Seedlings will be ready for transplanting in field in about 20-25 days of germination.
The ware crop from seedlings tubers can be raised following the standard agronomic practices of the area, keeping in view that smaller tubers are to be planted at closer spacing. The suitable inter & intra row spacing is 60 cm * 20 cm for 25-30 mm, 60 cm * 15 cm for 20-25 mm, 60 cm * 10 cm for 15-20 mm & 60 cm * 5 cm for 15 mm sized tubers. The field produce can be used as seed for at least 2 seasons in potatoes seed producing areas and for 1 season in other areas.
Raising crops from seedlings tubers:
In this method smaller tubers are made in the nursery beds and these are used as seed tubers to raise the ware crops next season. This method is suitable for regions having short growing seasons especially in the higher hills.
Prepare the nursery beds like that of seedlings transplanted in the fields. In the levelled nursery beds, 2-3 grams TPS is dibbled at 10 cm * 10 cm spacing at a depth of 0.5-1 cm. Irrigate the field immediately after sowing.
Germination take place in 15 days. Thinning is essential after 20-25 days to maintain optimum plant population in the field. Dehaulm the crop 90-100 days after sowing and dug out the tubers after 15-20 days.
The seed tubers produced in such a way have good quality and are used as ware crop during next year. The crop raised from seedlings tubers yield 20-25% higher than crop raised from good tubers of traditional varieties.
Advantages of True Potato seed (TPS) propagation:
- TPS technique is for disease free seed production. It is the technique for virus free seed production.
- The cost of tuber used in conventional method of planting is high however, the production of tuberlets in nursery for planting in coming season is relatively low.
- The cost required for storage of huge bulk of conventionally used tubers is higher which is reduced as tuberlets (small in size) require very small space for storage. It also reduces cost of transportation & transplantation.
- The viral infiltration in the seed tuber is also very less.
- The cost of tuber treating chemicals is also reduced because of relatively low volume of tuberlets.
- With this method, the disease-free potato seed can be produced & prevention of diseases to new areas can be done.
Seed plot technique (SPT) of potato under plains:
Disease free seed potato is being produced in the hills & are supplied to the farmers in Terai. However, due to low production there is a wide gap between demand of the disease-free seed than supply. In order to obtain healthy & high yielding seeds, farmers need to focus on the following points:
- Use of healthy & disease -free seeds from reliable source.
- Timely sowing (end of October) and select aphid free areas.
- Use of the whole tuber seeds at the spacing of 50 cm * 20 cm.
- Use of 3/4th dose of nitrogen.
- Use of insecticides (Rogor) to control aphids.
- Critical limit is 20 aphids per 100 compound leaves.
- Dehaulming is necessary (3rd week of January).
- 2 weeks onward of hand cutting harvesting is to be done.
- Sorting & tuber treatment (3% Boric acid for 30 min).
- Bagging & proper storage.
Calculate the required fertilizer for potato cultivation here.