About two lakh hectares of land are under sweet potato cultivation
SWEET POTATO is a nutritious tuber that is rich in beta-carotene and anti oxidants. Sweet potato is called Sakaravalli kizhangu in Tamil and Malayalam, Shakarkand in Hindi, Chilagada dumpa in Telugu and Genasu in Kannada.About two lakh hectares of land are under sweet potato cultivation in India. The crop is cultivated mostly in Orissa, West Bengal, Bihar and Eastern Uttar Pradesh. The crop can be cultivated three times in a year and hence there is a continuous supply of the tubers in the market, according to Dr. S. Edison, Director, Central Tuber Crops Research Institute (CTCRI), Sreekariyam, Thiruvananthapuram, Kerala.Researchers at the CTCRI have developed a short duration sweet potato variety named Sree Kanaka.
The yield level of sweet potato in countries such as China and Japan is about 16 tonnes per hectare, compared with India where the yield is only eight tonnes, according to Dr. Edison. The variety Sree Kanaka is characterised by cream coloured skin and dark orange coloured flesh.
The flesh of the cooked tubers makes it quite attractive for table purposes, according to Dr. Edison. The variety yields 10-15 tonnes per hectare. The plants possess thick vines, with dark purple coloured leaves. The tubers are cylindrical in shape.According to Dr. Edison, the variety has been found suitable for cultivating during Khariff (June-August) and Rabi (September-November) seasons. Generally, sweet potato is propagated by vegetative means. The nursery is raised from the stored tubers or vines. Vines produced from the nursery are healthy and vigorous compared with the vines from the freshly harvested crop.Giving details of the planting technique, Dr. B. Vimala, Principal Scientist of the Institute, said "about 5 tonnes of farm yard manure has to be applied and the land has to be ploughed into furrows or pits dug to a depth of about 20 cm."
Mounds, ridges and furrows or flat beds are the commonly adopted forms of land preparation. If the crop is to be planted on furrows then a spacing of about 60 x 20 cm is usually recommended for planting the vines. About 83,300 vine cuttings are required for planting in one hectare. Giving details on chemical fertilizers, Dr. Vimala said, "at the time of planting the vines about 55 kg of urea, 125 kg of Rajphos and 85 kg of potash should be applied." A month later, about 55 kg of urea should be applied as a side dressing and the soil around the crop should be earthed up. The tubers come to harvest in 75-85 days of planting.
Farmers are advised to harvest the tubers within the stipulated time because when the harvest gets delayed beyond 90 days the tubers develop pith formations and become hollow in the centre. "It was also observed by the researchers that the quality of tubers on harvesting deteriorated and they were found to have been infested with sweet potato weevil (Cylas formicarius )," Dr. Vimala said.
Indian children suffer night blindness due to lack of beta-carotene. Sweet potato varieties such as Sree kanaka have a very high beta-carotene content which in turn is the pre-cursor for Vitamin A, according to Dr. Edison.It will be good to suggest growing of sweet potato in school/ kitchen gardens and encourage boys & girls to consume this tuber, according to him. "One boiled tuber a day can give sufficient beta-carotene to the children at a very low cost," he said. For more information readers can contact the Central Tuber Crops Research Institute Sreekariyam, Thiruvananthapuram - 695017, Kerala, Phone: 0471-2598551, email: firstname.lastname@example.org