Biochemical Phenotyping of Soybean [ Glycine max (L.) Merill] Genotypes to Establish the Role of Lipid Peroxidation and Antioxidant Enzymes in Seed Longevity

Thirty-three soybean [ Glycine max (L.) Merill] genotypes, comprising 14 black-seeded and 19 yellow-seeded ones, were selected on the basis of their reported storability for the biochemical phenotyping to establish the role of lipid peroxidation and antioxidant enzymes in seed longevity. The present study revealed clear genotypic variability with respect to storability among different soybean genotypes. Good-storer genotypes with lower electrolyte leakage were characterized by smaller seed size with black testa color. The level of volatile aldehydes released and lipoxygenase II enzyme activity were higher in the yellow-seeded genotypes than in the black-seeded genotypes, though it increased in all during ageing. A sharp increase in the release of volatile aldehydes and lipoxygenase II activity, concomitant with the reduction in germination under uncontrolled laboratory conditions of storage indicated the role of lipid peroxidation in seed longevity behavior ( r = −0.6638** and r = −0.7639**, respectively). No significant difference was noted in the mean hydroperoxide lyase activity of black and yellow-seeded genotypes. However, maintenance of high hydroperoxide lyase activity during storage resulted in higher release of volatile aldehydes and poor storability of seeds. Significantly higher antioxidant enzyme activity was recorded in the black-seeded genotypes than in the yellow-seeded ones, though there was a reduction in hydroperoxide lyase activity during storage in all the genotypes. The viability of black-seeded genotypes after storage for 1 year was better than the yellow-seeded genotypes.