Rainfed rice - IRRI books - International Rice Research Institute

Trends in varietal
improvement
In the past, varietal development has
focused mainly on increasing yield.
Lately, the focus has widened to
include resistance to major pests and
diseases. Now, quality is also being
emphasised.
Over the past 35 years, more than
512 high-yielding varieties have been
released in India. About 67 of these
are on the national seed chain but
only one-third of these 67 have been
widely adopted and popularised.
Traditional Varieties vs. Modern Varieties: Potentials and Risks
Bulk breeding
Bulk breeding is an alternative to the pedigree method in
which each generation (beginning with F 2 ) is harvested in
bulk until homogeneity is attained (F 5 to F 7 ). Natural
selection, which favours plants that produce more seeds in
the final bulk generation, is allowed to take its course. The
best plants are selected and their seeds are sown in
pedigree rows or observation plots. Uniform lines are
entered for yield trials.
The facts . . .
63.3% of the total rice area in the country is
in eastern India.
A recent sampling done with farmers in
some cluster villages of Orissa showed
that 30 indigenous varieties and 11 highyielding
varieties are being used. More
than 70% of the farmers are growing two
to five traditional cultivars while 20% are
growing six to eight traditional varieties.
In another case study done on upland rice in
Hazaribagh, it was found that 93% of the
farmers have no access to modern varieties.
This indicates that varietal improvement 'is still
slow in rainfed environments.
Potentials and risks
There is no question that modern varieties have greater yield potential than
traditional varieties. However, they are also more prone to risk in situations
involving stress or epidemics. Traditional cultivars, on the other hand,
possess the inherent capacity to withstand stress and adverse environments.
These varieties may have low to moderate yields under adverse conditions,
whereas modern varieties may fail completely.
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