Maize seeds assume desiccation tolerance as they dry naturally during maturation and pre drying at 35ºC after their physiological maturity can induce tolerance to artificial drying at 50ºC. Seeds of 'BRS-3060' harvested with 42,2% water content and submitted to increased periods of pre-conditioning, showed enhanced tolerance to 50ºC until 25,9% water content when they reached maximum physiological performance. Seed quality was evaluated by germination and vigor tests and a-amilase enzyme activity. Seeds tolerant and not-tolerant to drying at 50ºC were investigated by means of electrophoretic standards of free radical-scavenging enzymes and lea proteins. The scavenger activity enzyme superoxide dismutase, peroxidase and catalase was detected in 5-day old seedling hypocotyl and lea protein was detected in embryonic axes. The results showed that maize seeds tolerant to 50ºC are associated to catalase enzyme activity but are less related to superoxide dismutase and peroxidase enzymes activities. Lea proteins were not present in maize seeds non tolerant to desiccation and their presence was associated to the physiological performance of tolerant seeds.
Zea mays; desiccation tolerance; peroxidase; superoxidase; catalase
