Relationship among yield components and selection criteria for yield improvement in winter rapeseed (Brassica napus L.)

摘要

Twenty-five winter type rapeseed varieties introduced from diverse sources of the world were studied for variability, heritability, genetic advance, correlation and path analysis of seed yield and yield components. Significant differences among genotypes for most of the traits indicated that there is sufficient variability available to have an effective selection. Genotypic and phenotypic variances were highest for pods/plant followed by plant height, whereas the maximum genotypic and phenotypic coefficients of variability were found in seed yield/plant and pods/plant, respectively. Broad sense heritability estimates ranged from very low to high. Maximum heritability of 0.903 was obtained for days to maturity followed by flower duration (0,662), seed weight (0.548) and seed yield (0.477). High heritability for flower duration, seed weight and seed yield coupled with high genetic advance indicated that these traits could be improved through mass selection. Positive and significant correlation was found between seed yield and harvest index, seed weight and flower duration. Significant and positive correlation of seed weight with harvest index, flower duration and seed yield indicated that improvement in seed weight will give higher harvest index ultimately resulting high seed yield. Harvest index, seed weight and pods/plant have shown a considerable direct positive effect on seed yield. Positive direct effect of seed weight and harvest index associated with significant and positive correlation with seed yield suggested that these yield components may be a good selection criteria to improve seed yield of winter type rapeseeds.