Study of physiological maturity of melon seeds by enzymatic changes1

-Plant species have different adaptation mechanisms regarding seed survival to desiccation, preventing cellular destruction during the water loss. The knowledge of these mechanisms is of great importance for the understanding of how the seed formation/maturation processes and the processes involved in germination occur. Thus, this study aimed to determine physiological and enzymatic changes during the maturation process of melon seeds of the cultivar BRS Anton, obtained from fruits at different maturation stages and subjected to post-harvest storage, by the action of total proteins and the enzymes catalase, peroxidase, and superoxide dismutase. Melon fruits were grown in a greenhouse at Embrapa Vegetables and harvested at five different times: 30, 45, 60, 75, and 90 days after anthesis (DAA). Thirty fruits were harvested in each season and 15 fruits had their seeds extracted immediately after harvest and the other 15 fruits were stored for 15 days. After processing and drying, the seeds were submitted to the following analyses: germination, first count, protein profile analysis, and activity of antioxidant enzymes (total proteins, peroxidase, catalase, and superoxide dismutase). The activity of the antioxidant enzymes from 60 DAA under storage showed a more orderly behavior, reaffirming the results of physiological tests. It shows that the seeds at this point of physiological maturation are well-formed and drying caused no damage to their cell membranes.