大豆种子萌发对镉与模拟酸雨胁迫的响应

为了解土壤中镉(Cd)与酸雨对作物种子萌发的环境生物学效应,采用种子常规萌发试验研究了不同浓度的Cd~(2+)溶液与模拟酸雨复合污染对大豆种子萌发过程中发芽率、发芽势、发芽指数、活力指数变化的影响.结果表明,Cd~(2+)对大豆种子萌发的毒害作用比酸雨明显,是构成复合污染的主要因素.Cd~(2+)和酸雨复合污染对大豆种子发芽率和发芽势有显著的正交互作用效应,即存在协同作用.Cd~(2+)与酸雨复合污染对大豆种子发芽指数和活力指数都有影响,但不表现出显著的交互作用效应,表明复合污染对这两项指标是两种污染物单因素效应的简单叠加.综合考虑,Cd~(2+)与酸雨复合污染对大豆种子萌发表现出明显的协同作用.

Effects of the soil cadmium and the simulated acid rain on the soybean seed germination

This research is aimed to explore the effects of the joined pollution of the soil cadmium (Cd~(2+)) and the acid rain on the crop seed germination so as to disclose the biological effects of the environment on the growth of the crop. In DOIng our experiments, we have adopted different concentrations of Cd~(2+) solution under six simulated acid rain solutions, namely, those of pH 2.5, 3.0, 3.5, 4.0, 5.0, 5.93 and the neutral solution(pH 7.0) in laboratory conditions. As the first step, the soybean seeds were disinfected for 8 minutes by HgCl_2 and pretreated with the corresponding solutions for 24 hours. Then, the pretreated soybean seeds were put into culture dishes with filter sheets and let to be germinated in a culture container kept in a constant temperature of 25 ℃, in which each group was treated with 100 seeds being experimented in each, respectively. And, then, the seeds were submerged in the corresponding solutions in a depth of about two-thirds of the seeds. In the germination process, the seeds were let to be exposed to the corresponding solutions that were expected to be replaced everyday for 7 d until the germination was over. And, finally, the germination rate, energy, index as well as the vigor index were tested and measured under different degrees of stress. The results of our experiments show that Cd~(2+) stress, the main factor of the joined pollution proved to have brought about stronger toxic harm than the toxic harm of acid rain on soybean seed germination. There exists synergistic effect on soybean seed germination rate and germination vigor between Cd~(2+) and acid rain stress. But there has no significant positive interactive effect on the germination index and vigor index by Cd~(2+) and acid rain stress. It indicates that the effects of Cd~(2+) and acid rain stress on the soybean seed germination were just the two single-factors added. The result also indicates that the synergistic effects on soybean seed germination between Cd~(2+) and acid rain combined pollution could be observed. As stress enhanced, synergistic effects of inhibiting seed germination on soybean seed germination between Cd~(2+) and acid rain combined pollution in soybean were more significant.