酸雨胁迫对水稻萌发种子能量代谢的影响

Study on the effect of acid rain stress on the energy metabolism of rice seedling germination

为探讨酸雨对水稻种子萌发时能量代谢的影响,采用pH =2.0、2.5、3.0、4.0、5.0的模拟酸雨处理水稻(宁粳Ⅰ号)种子,研究不同强度酸雨胁迫对水稻种子呼吸速率、CAT活性、呼吸商、线粒体蛋白与ATP含量及能荷的影响。结果表明,酸雨(AR)连续作用7d后,随着pH值的降低,酸雨对水稻种子造成的伤害增强,而水稻种子的呼吸作用与能量代谢减弱。酸雨胁迫强度与水稻萌发种子各呼吸指标间呈剂量-效应关系,具体表现为酸雨胁迫强度增大时,呼吸速率下降,线粒体蛋白含量减少,ATP含量降低,能荷呈下降趋势且降幅随AR胁迫强度的增加而增大。研究表明,酸雨胁迫下种子能量代谢受到抑制是抑制种子萌发的原因之一。

The present investigation intends to discover the effect of acid rain stress on the energy metabolism of seed germination with rice （ Oryza sativa ） seeds as experimental materials. To be exact, our investigation is to disclose the effects of acid rain on the seedling germination plants in acidic deposition area both quantitatively and qualitatively and in turn to determine the reasons of the rice growing and declining dynamics with the change of average rice yield. For our purpose, we have taken six simulated acid rain （SAR） solutions with ~ the respective pH values being 2.0, 2.5, 3.0, 4.0 and 5.0 and neutral solution （pH = 7. 0） as control group. In proceeding to our experiments, pretreated rice seeds were placed in culture dishes with filter sheets to germinate in a culture container at a constant temperature of （25 ± 1.0） ℃, in which each treatment group is placed in three separate dishes with each dish having 50 seeds. In the process of germination, seeds were exposed to the simulated acid rain that was to be changed each day. After 7 d treatment by the simulated acid rain, the respiratory rate, CAT activity, respiratory quotient, mitochondrial protein and ATP contents, as well as energy charge were tested. The results of our investigation have shown that after 7 d SAR continuous treating, the damage caused by the acid rain increased with the decrease of pH value. Meanwhile, the respiration and energy metabelism during the rice seed germination tends to decrease. Moreover, the effects of stress levels of acid rain on the respiratory rate, CAT activity, respiratory quotient, mitochondrial protein and ATP contents, and energy charge during rice seed germination reveal the dose-effect relationship. Compared with CK, the respiration rate under SAR stress tends to decrease and the mitochondrial protein content, ATP content and energy charge indicate the decreasing effect. Furthermore, such decreasing tendency turns to be aggravated with the stress levels of acid rain increased. Thus, our experimental results show that acid rain stress is one of the causes leading to the inhibition of seed germination.