ABA诱发二次休眠对油菜种子抗老化的效应

Effect of Secondary Dormancy Induced Abscisic Acid on Resistance to Senescence of Brassica napus Seeds

研究表明,油菜种子的休眠与萌发受到内源ABA的明显调节.刚采收的浅休眠种子,体内积累有较高的ABA含量,而后熟后的非休眠种于ABA含量明显下降.以外源500—1500ppm ABA在25±0.5℃处理油菜非休眠种子24小时,可以有效地诱发二次休眠,室内条件下干藏休眠期可持续35周左右.自然及人工加速老化(种子含水量7%、50℃;相对湿度100%、40℃)看出,在能够诱发二次休眠的ABA处理中,并非处理浓度愈高,诱眠程度愈深,致眠种子抵御衰老的效果就越好.500ppm ABA对改善种子耐贮性能有一定效果,但1500ppm ABA处理则过高地促进了体内ABA积累,反而有加这种子衰老劣变的趋势.只有 750 ppm ABA才是诱发种子二次休眠、增强抗老化能力最佳处理浓度.

The seeds of the non-dormant rape cv. Ningyou No. 7( Brassica napus L. )were used as experi-mental material. Endogenous abscisic acid (ABA) and gibberellic acid (GA) in fresh and after-ripening seeds were determined by Enzyme Linked Immunosorbent Assay (ELISA) and Radioimmunoassay (RIA) respectively. Accelerated ageing of seeds was carried out in two environments; (1) seeds of 7% moisture content,at 50 for 5 days; (2)seeds of natural moisture content,at 100% relative humidity and 40 for 4 days. Seeds af ter natural ageing at room temperature and humidity for 115 weeks were analysed for the compositon of fatty acids. It was found that the dormancy and germination of rape seeds was obviously regulated by endoge- , nous ABA. There existed the high ABA level in fresh seeds with weak dormancy and the low one in after-ripening seeds with no dormancy. The secondary dormancy of non-dormant seeds was effectively induced with the seed-soaking of 500-1500 ppm exogenous ABA at 25 0. 5 for 24 hrs and the duration of secondary dormancy reached 35 weeks or so at room temperature and humidity. Analy-sis of results of natural and accelerated ageing indicated that increasing concentration of exogenous ABA and degree of induced secondary dormancy did not result in ever strengthening resistance of treat-ed seeds to deterioration. To a certain extent,500 ppm ABA treatment improved seed storability. How-ever, 1500 ppm ABA treatment,which might have promoted the accumulation of endogenous ABA ex-cessively,accelerated the ageing of treated seeds. 750 ppm of ABA was the optimum concentration for secondary dormancy induction, by which the treated seeds showed high resistance to natural and artif i-cial ageing.