Genetic variability and character association studies in rainfed upland rice (Oryza sativa L.)

A study to obtain information on genetic variability and inter-relationship of grain yield and associated characters under rainfed upland conditions was carried out using 44 diverse genotypes. The analysis of variance revealed the significant differences among the genotypes for all the traits indicating presence of sufficient variability among the genotypes for various traits. High estimate of genotypic and phenotypic coefficient of variation were observed for number of grains per panicle, grain yield per plant, straw yield per plant and harvest index indicated wider genetic variation for these traits.. High value of heritability coupled with high expected genetic advance as per cent of mean were observed for the characters number of grains per panicle, grain yield per plant, straw yield per plant, harvest index, 1000-grain weight, grain L/B ratio and amylose content indicated that selection may be effective for this character. The results of correlation studies indicated that genotypic correlation coefficients were higher in magnitude than their corresponding phenotypic correlation coefficients for most of the traits. Grain yield per plant was found positively and significantly associated with plant height, panicle length, number of total tillers per plant, number of effective tillers per plant, number of grains per panicle, harvest index and 1000-grain weight at both genotypic and phenotypic levels indicating that these traits were main yield attributing traits. Path analysis revealed that straw yield per plant had the highest positive direct effect on grain yield followed by grain length, harvest index, days to maturity, protein content, number of total tillers per plant and number of grain per panicle. For maximizing the grain yield per plant emphasis should be given in selection of characters such as number of grains per panicle, straw yield per plant, harvest index and 1000 grain weight for further improvement of upland rice.