Genetic variation and character association for grain yield and component traits in traditional rice (Oryza sativa L.) cultivars of Assam

An experiment was conducted with a view to obtain information of genetic parameters of variation and character association for 13 quantitative traits in a set of 64 rice cultivars of Assam. The study revealed signifcant diferences for all the traits under study. Highest genotypic coefcient of variation was observed for the trait biological yield followed by harvest index and grain yield. More than 80% heritability was observed for all the traits except grain yield, efective tillers per plant and biological yield. Genetic advance as per cent of mean was highest for biological yield followed by harvest index, flled grains per panicle and grain yield. Higher magnitude of genetic advance along with considerably high heritability observed for harvest index, flled grains per panicle and biological yield indicated that these traits could be considered for selection to obtain high genetic gain. Character association studies indicated that direct selection of 100 - grain weight, grain length, grain breadth, biological yield and harvest index, would bring about improvement in grain yield. Non-signifcant association of grain yield with important yield attributes viz., flled grain per panicle, tillers per plant and panicle length were due to their strong association with duration of genotypes, which in turn was negatively associated with grain yield. Recombination breeding and recurrent selection, therefore, could be suggested to break the negative linkage in order to achieve further genetic improvement.