Abstract:

Recalcitrant seeds of Trichilia dregeana Sond. were used as experimental material, and desiccation sensitivity of T. dregeana axes and antioxidant role of ascorbic acid were studied. Desiccation tolerance of T. dregeana axes progressively declined with dehydration, water content at which 50% of axes has been killed by dehydration (W₅₀) was about 0.16 g H₂O/g DW. During dehydration, electrolyte leakage rate of axes gradually increased, the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR) and dehydroascorbate reductase (DHAR) declined, and content of thiobarbituric acid (TBA)-reactive products increased. Two point five-10 mmol/L ascorbic acid (AsA) treatment could significantly increase desiccation tolerance and activities of SOD, APX, CAT and GR in axes, and decrease electrolyte leakage rate and content of TBA-reactive products in axes. The results showed that desiccation tolerance of T. dregeana axes was strongly correlated with the increase in the activities of antioxidant enzymes and the decrease in lipid peroxidation.

Key words: ascorbic acid, ascorbate peroxidase, catalase, dehydroascorbate reductase, glutathione reductase, lipid peroxidation, recalcitrant seed, superoxide dismutase