Interrelationship between yield and yield components in common bean (Phaseolus vulgaris)

The present study was undertaken to arrive at a selection index based on various yield traits that have significant contributions towards grain yield. The material consisted of 60 diverse genotypes of bean, out of which 45 were received from Nordic Gene Bank, Sweden and 15 were local collections. Seed yield had significant positive co-relation with number of pods/plant, 100-seed weight, number of branches/plant, plant height and seeds/pod. Among the component traits, significant positive co-relation was recorded for days to 50% flowering with days to maturity and number of primary branches/plant; days to maturity with plant height, plant spread and number of primary branches/plant; plant height with plant spread and 100-seed weight; plant spread with number of branches/plant, pod length, and 100-seed weight; number of branches/plant with number of pods/plant, pod length and seeds/pod; and number of pods/plant and pod length with seeds/pod. This clearly indicates the complex picture of interrelationship between grain yield and the component traits. Path co-efficient analysis revealed that highest direct effect on yield was exerted by 100-seed weight (4.112) followed by plant height (2.003), number of pods/plant (0.818) and days to maturity, while as highest direct effect on seed yield was exerted by plant spread (−0.169) followed by days to maturity (−0.012) and pod length (−0.009). The lower yield of plants with greater spread could be due to poor source-sink relationship despite higher biomass. The negative co-relation of seed yield with days to 50% flowering, may be due to less accumulation of photosynthates in early types. In light of the results of present study, it could be concluded that traits like 100-seed weight, number of pods/plant, seeds/pod, number of branches/plant, plant height and days to maturity could be used to devise an efficient selection index in rajmash to bring about an improvement in seed yield, by selecting plants with higher values for such traits.