Genetic worth and stability of selection indices in rice (Oryza sativa L.)

Improvement of one trait on its own will affect the performance of other traits because ofgenotypic correlations between traits. Index selection is one of the tools used by plant breedersto overcome this problem. The purpose of this paper is to evaluate selection indices developedfor improving grain yield in rice (Oryza sativa L.). Forty-nine rice genotypes were cultivated atTonekabon Rice Research Station, Iran, in 2009 and 2010. Selection indices were developedbased on phenotypic and genotypic correlations, path coefficients, broad-sense heritability oftraits and stepwise multiple linear regression coefficients. Assessment of indices revealed thatthe stability decreased concurrently with increase in the genetic worth, and hence an inverseassociation existed between stability and genetic worth of indices. The results also suggestedthat selection for TP, GW, GP and GL and against PH using their multiple linear regressionparameters as economic weights was an effective criterion for improving grain yield in ricegenotypes. On the other hand, the most stable indices were those that were developed based onheritability of traits as well as genotypic path coefficients.