Effect of different drying rates on the desiccation tolerance and antioxidant enzyme activities of Baccaurea ramilfora (Euphorbiaceae) seeds.

The effects of different drying rate on desiccation tolerance and ntioxidant enzyme activities of Baccaurea ramilfora seeds were studied in this paper. The initial water content(WC) of B.ramilfora seeds was high 1.72 g H2O·g-1DW,and germination was 86.67%,respectively. When the seeds dehydrated to the same water content (0.90g H2O·g-1DW),the germination of seeds increased with slwo-dehydrated method ( 97.78%),while decreased with rapid-dehydrated method ( 64.44%). The germination of rapid-dehydrated seeds with 0.76 g H2O·g-1DW WC was 21.67%,while that of slow-dehydrated seeds with 0.68 g H2O·g-1DW WC was 55.56%. The B.ramilfora seeds were recalcitrant seeds which showed higher tolerance to slow dehydration. Both of relative electrolyte leakage and lipid peroxidation increased following hedehydration,and the increase rate of slow-dehydrated seeds were slower than rapid-dehydrated seeds. Among these antioxidant enzymes,the activities of SOD,DHAR and APX were higher in rapid-dehydrated seeds than slow-dehydrated seeds,while CAT was lower,and GR was not found. These results indicated that CAT played more important role in desiccation tolerance of B.ramilfora seeds than the other antioxidant enzymes.