Package of Practices for Cultivation of Diascoria
Family: Dioscoreaceae
This Genus Dioscorea belonging to family Dioscoreaceae with" over 600 species is widely distributed in tropical world. Some of the species like D. alaia and D. esculeniaaxQ under cultivation for long time for their edible tubers. There are about 15 species of this genus containing diosgenin. Among this, D. floribunda and D composita are widely grown for dios genin production.
Climate and Soil:
It is a tropical species preferring a tropical climate without extremity to temperature. It is adopted to moderate to heavy rainfall areas. Dioscorea plants can be grown in a wide variety of. soils. Extremely heavy clay soils are, in general not recommended, as they restrict tuber growth and make harvesting difficult. Dioscorea tolerates fairly wide variation in soil pH, though very acid soils should be avoided, the ideal soil pH being 5.5 to 6.5.
Varieties:
The Indian Institute of Horticultural Research, Bangalaore has released so far two improved varieties.
l. FB{c} l:
This is a composite strain of D. floribunda, which has been released for commercial cultivation. This is a vigorous growing strain relatively free from diseases. This has a diosgenin content of 3 to 5.5 per cent. It is suitable for cultivation around Bangalaore and Coorg (Karnataka), goa, Assam, Maghalaya, Tamilnadu, Maharashtra and Andaman.
2. Arka Upkar:
This is a high yielding clone released recently.
The plants are very vigorous with a stout, robust vine, bearing broad dark green leaves. The tuber branches are thick, broad and deep. It has a higher diosgenin content of 3.5 to 4.0 per cent.
Propagation:
Dioscorea floribunda can be propagated by tuber pieces, single node stem cuttings or seed. Commercial planting is normally established by tuber pieces only. Propagation, through: seed progeny is. variable and it may take longer time to obtain tuber yields.
Planting:
Land should be prepared thoroughly till a fine tilth is obtained. Deep furrows.should be made at 60 cm distance with the help of a plough. The stored tuber pieces which are ready for planting, seedlings or single node stem cuttings should be planted in furrows with 30 cm between the plants for-one year crop and 45 cm between the plants for two years crop; The tuber pieces are planted at about 0.5 cm below the soil level. The new sprouts should be staked immediately. After sprouting is complete, the plants could be earthed up. Soil from the ridges may be used for earthing up so that the original furrows will become ridges and vice versa.
Aftercare:
Dioscorea vines need support for their optimum growth and hence the vines are trained over pandal system or trellis.
Weeding:
Initially, the vines are weak and tender and can not compete efficiently with the surrounding weeds. Periodic hand weeding as and when necessary, is essential for the first, few months. . Experience has shown that once the plants have climbed up on the pandala, the weed population is considerably reduced due to shading. The plants by this stage can also compete more successfully with weeds.
Manures and Fertilizers:
D. floribunda requires high organic matter for good tuber formation. Besides a basal dose of 18 to 20 tones of FYM per ha, a complete fertilizer dose of 300 kg nitrogen, 150 kg phosphorus and 150 kg "of potassium should be applied per hectare. Phosphorus and potassium should be applied in two equal doses one after the establishment of the crop during May-June and the other during vigorous growth period of the crop (August – September).
Irrigation:
Irrigation may be given at weekly intervals in the initial stage and afterwards at about 10 days interval. However, during rainy season no irrigation is needed. In anamalais, it is raised under pure rainfed conditions. Intercropping.
Intercropping with legumes like cowpea, horse, gram, cluster bean and French bean has been found to smother weeds and also provide an extra income without adversely affecting the tuber yield and diosgenin content.
Duration:
The diosgenin content tends to increase with age; (.5 to 3.0 per cent during the first year and.3.0-3.5 per cent in the second year) and also the tuber yield and hence a two year crop is found to be: more economical.
Harvesting:
The tubers grow to about 25-30 cm depth and hence harvesting is done by manual labour. The best season for harvesting is Feb. – March coinciding with the dry period.
On an average 50-60 tones of fresh tubers can be obtained from ome hectare in two years duration.