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Lesser yam (Dioscorea esculenta) is predominantly a tropical plant. The
crop cannot withstand frost and excessively high temperatures. Temperature around
30ºC and rainfall of 120-200 cm distributed throughout the growth period are ideal.
Day length greater than 12 hours during initial stages and shorter day length during
the later part of the growing season favour satisfactory tuber formation. Yam requires
loose, deep, well-drained, fertile soil. The crop does not come up well in waterlogged
conditions.
Season
Seed tubers are normally planted during the later part of the dry season (March-April)
and start sprouting with the onset of pre-monsoon showers. If the planting is delayed,
yams start sprouting in storage, which is not desirable for planting.
It is grown in a similar agro-climatic situation as that of D. alata. Planting
season and manuring are also similar.
Varieties
Sree Latha: This is a selection
from Thiruvananthapuram district with a duration of 8 months. Tubers are oblong
to fusiform with creamy white flesh. Vines twine to the left.
Sree Kala: This is an early
variety with 7.5 months duration. The tubers have 35-37% dry matter, 23-25% starch
and 1-1.3% sugar.
Seeds and sowing
Select medium size tubers weighing about 100-150 g each. Plant the whole tuber,
one in each mound and cover completely with soil. Mulch the mounds to maintain optimum
temperature and moisture. To plant one hectare 1800-2700 kg of seed materials are
required.
Preparation of land
Plough or dig the land to a depth of 15-20 cm. Prepare mounds at a spacing of 75
x 75 cm incorporating cattle manure @ 1 kg per mound.
Manuring
Apply cattle manure or compost at 10-15 t/ha as basal dressing. A fertilizer dose
of 80:60:80 kg of N:P2O5:K2O per ha has to be applied
in two splits; half dose of N, full P2O5 and half of K2O
within a week after sprouting; remaining half N and half K2O one month
after the first application along with weeding and earthing up.
Trailing
Trail the vines by fixing small poles attached with coir rope and direct 4-6 plants
per pole.
Harvesting
The crop is ready for harvest by about 7-8 months time. Tuber yields of 20-25 t/ha
can be obtained by following the improved methods of cultivation.
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