Dioscorea (Dioscorea alata L. & Dioscorea esculenta L.)
Dioscoreaceae

Varieties
Peruvalli (D.alata)              : Co 1, Sree Roopa, Sree Keerthi, Sree Shilpa
Siruvalli (D.esculenta)        : Sree Latha, Sree Kala
 
Co 1 (Dioscorea alata)
Soil and climate
It requires warm and humid conditions with a mean temperature of 300C and a well distributed annual rainfall of 1200-2000 mm. Sandy loam soil with a pH of 6.0 to 6.5 is preferred with good drainage and cool weather.

Season
May – June is suitable for planting.

Seed rate
Use mature tubers or pieces of tubers taken from the previous crop as seed material at the rate of 1875 – 2500 kg/ha.

Preparation of field
Plough the field to a fine tilth and form ridges and furrows at 75 cm spacing.

Planting
Mini setts weighing 25 g are recommended for planting directly in the field or raising a nursery and transplanted after 60 days. Planting is done in beds or in ridges or in mounds or in rows 75 cm apart either way.

Irrigation
Copious watering once in a week is necessary.

Application of fertilizers
Apply FYM @ 25 t/ha at the time of last ploughing. Follow fertilizer schedule of 40:60:120 kg NPK/ha as basal. Apply 4 kg/ha of Azospirillum (mixed with 40 kg of soil) 30 days after planting. Apply 50 kg N and 120 kg K/ha on 90 days after planting. Go for weeding before top dressing, followed by earthing up.

After cultivation
The vines should be trained on bamboo poles. Weeding can be done as and when necessary. It can be intercropped profitably in coconut, arecanut, rubber, banana and robusta coffee plantations at a spacing of 90 x 90 cm. In Robusta banana + Dioscorea system, banana should be manured at the full recommended dosage and for yams, manuring at the 2/3rd recommended level is sufficient.

Trailing
Trailing is necessary to expose the leaves to sunlight. It is done within 15 days after sprouting by coir rope attached to artificial supports in the open area or to the trees where it is raised as an intercrop.

Crop protection
Yam scale is found to occur on the tubers both under field and storage conditions. As a prophylactic measure, dip the planting material in Methyl demeton 0.25 per cent. Use scale free seed tuber for planting.

Harvest
Greater yam and white yam become ready for harvest by 9-10 months after planting. Lesser yam takes 8-9 months for attaining maturity. Carefully dig out the tubers without causing injury.

Yield
It can yield about 20 – 25 t/ha in 240 days of tubers.

Updated on : 26.08.2013