ABSTRACT

Five short season cultivars (SSC) with no premature senescence were selected to cross with 5 SSC cultivars with premature senescence. The parents, F1, and F2 from the reciprocal crosses were field tested in replicated trials in 2001 and 2002. The results indicated that the activities of protecting enzymes of the antioxidant system such as CAT, SOD, and POD were higher in the early maturing SSC with no premature senescence than these in the SSC parental cultivars that showed premature senescence, while the MDA content in the former was lower than that in the latter. Various genetic variances and heritabilities for these biochemical traits and IAA, ABA, and chlorophyll contents were also estimated. There existed significant additive variance for CAT, POD, ABA and IAA, while CAT specific activity and SOD activity were largely controlled by dominant effects. Both maternal and dominant variances played equally predominant roles in POD and SOD specific activity, MDA and soluble protein contents. The relative contributions of the various genetic components to the phenotypic variation varied in boll-setting period.