Climate and Soil
Sweet potato requires a long warm growing season. Plenty of sunshine and moderate rainfall with warm night and days for four months are best suited for it. It is drought resistant vegetable and cannot stand frost. Sweet potato can be grown on a wide range of soils but loamy sand soils are invariably regarded as suitable for sweet potato. The optimum pH range is 5.8 to 6.7.
Punjab Sweet potato–21 : Vines are medium long in length.Leaves are dark green, broad, lobed with purple tinge. Stem is medium long and thick. Its inter nodal length is 4.5 cm and petiolar length is 9 cm. It matures in about 145 days. Tuber skin color is deep red with white flesh. The tubers are 20 cm long with 4 cm width. Average tuber weight is 75 g. It has 35% dry matter and 81 mg/g starch. It gives about 75 quintals tuber yield per acre.
Land Preparation : The land should be well prepared and of good tilth for sowing sweet potato. The field should be ploughed 3-4 times followed by planking. The field should be free from weeds.
Seed Rate and Time of Planting : 25,000 to 30,000 cuttings of vines are sufficient for one acre. Use 35-40 kg tubers in half akanal area during January to February for raising vines in nursery beds for planting one acre. The optimum time of planting is from April to July.
Spacing: The vines are planted with line to line distance of 60 cm and plant to plant distance of 30 cm.
Manures and Fertilizers
Apply 10 tonnes of farmyard manure with 30 Kg N (125 kg CAN)25 Kg P2O5 (155 kg Single Superphosphate) and 20 Kg K2O (35 kgMuriate of Potash) per acre.
Earthing up : Earthing up should be done after 40 days of planting.
Irrigation : Irrigation may be given at 14 days interval.