Path analysis revealed that total tillers, spikelet fertility
and panicle weight had direct and significant correlation with single plant yield and
therefore selection based on the same can aid for genetic improvement. The 30 genotypes
were grouped into nine and seven clusters based on Tocher's and Ward's method,
respectively, with single plant yield contributing much to the total genetic divergence. It also
indicated that Ward's method is superior to Tocher's method in resolving genotypes into
different clusters. Based on Tocher's method of clustering, intercrossing between genotypes
of cluster VII and cluster IX may throw an array of recombinants in the segregating
generations for effective selection under saline alkaline condition.
In general, rice is life for Asians and in particular for Indians, as it provides
43% calorie requirement for more than 70% of the population (Rahman, 2006). Rice
is planted in 40 mha with a production of 87.8 MT and the demand for rice is
expected to be 100 MT during 2010 and 140 MT by 2025. This has to be achieved against
the backdrop of diminishing natural resource bases like land, labor and water
(Mishra et al., 2003).
Among various abiotic stresses that limit rice productivity, salinity is a
serious threat and it is further aggravated owing to the use of poor quality water for
irrigation, improper drainage (Chinnusamy and Zhu, 2003). In India, out of 8.6 mha of
salt affected soils, 2.19 mha are coastal saline where rice is the predominant crop
which is subjected to 12% loss in the production system due to abiotic stresses
(Singh et al., 2003).
The strategies for mitigating saline alkaline problem in crop production
include both development of management options and genetic improvement of
salinity tolerance in the present day varieties (Shannon, 1997). Although, the use of
some management options can ameliorate yield reduction under salinity
stress, implementation is often limited because of cost and availability of good quality
water resources. Therefore, the development of salt tolerant varieties would be a
practical solution to address this problem. |