Heterosis, character association and path analysis for grain protein content in rice (Oryza sativa L.)

Rice grain protein content has many unique activities like hypo-allergenic, anticancer properties etc. which helps in reducing protein energy malnutrition. The knowledge on the magnitude of genetic effects and association of traits helps in identifying desirable superior hybrids to enhance protein content coupled with yield. The experimental material consisted of 30 hybrids generated in full diallel mating design by hybridizing six parents differing in protein content. The promising hybrid combination IG74 / Gandhasala, its reciprocal cross and IG74 / TKM13 exhibited significant standard heterosis over the high protein check IG74 and the crosses TKM13 / CO52, CO52 / Vellai chithiraikar and CO52 / Gandhasala were adjudged as heterotic promising hybrids for the yield when compared with the check CO52. The grain protein content was found to be negatively associated with grain yield but had positive association with thousand grain weight and number of productive tillers per plant. Path analysis indicated that protein content had a negligible direct effect over grain yield and had positive indirect effect through thousand grain weight whereas having negative indirect effect through number of filled grains. Therefore, it is suggested that selection of parents for high test weight would help to identify good genotypes with high grain yield and protein content.