Assessment of genetic variability, correlation and path analyses for yield and its components in soybean

A study was conducted at the National Agriculture Research Center, Islamabad during summer 2001 on 27 genotypes of soybean to determine the correlation and path analyses of yield and its components. Significant differences among genotypes for characters viz., leaf area, chlorophyll content, first pod height, days to 50% flowering, days to flowering completion, days to pod initiation, days to 50% maturity, plant height, number of pods per plant, number of branches per plant, number of unfilled pods, number of shattered pods, 100-seed weight, grain yield and oil content were observed while protein content was statistically non-significant. Genotypic correlations were higher than the phenotypic and environmental ones for most of the characters exhibiting high degrees of genetic association among traits under consideration. Correlation coefficient for bean yield was positive with leaf area, first pod height, days to flowering, days to maturity, plant height and number of branches per plant. Therefore, increase in these traits will ultimately increase the grain yield. Path coefficient analysis revealed that days to flowering completion had maximum direct contribution to yield followed by days to pod initiation, chlorophyll content, number of pods per plant and plant height. It is suggested that these characters can be considered as selection criteria in improving the bean yield of soybean genotypes.