酸雨对3类不同抗性种子萌发过程的影响Ⅵ——酸雨胁迫对3类种子萌发POD活性的影响

Effects of Acid Rain on Activity of Peroxidase (POD) in Seed Germination of Three Plants Under Time Stress

试验采用不同pH值的模拟酸雨处理3类不同抗性种子,测定了酸雨胁迫对种子萌发过程膜脂过氧化及POD活性的影响。结果表明,萌发7d时,3类种子POD活性随胁迫强度增加而先升后降;丙二醛(MDA)含量升高,且处理组高于CK;3类种子对酸雨胁迫的抵抗能力为水稻>小麦>油菜。考察3￣7d的动态变化时发现,不同种子,不同处理条件下,各项生理生化指标的动态变化曲线不尽一致,但随着时间的推移,POD活性均有不同程度的增加,MDA含量变化也表现相应的增加趋势,同时也反映出相应的剂量效应和防护效果。

To study responses of seed germination of 3 kinds of seeds on acid rain stress, rice (O. sativa), wheat (T. aestivum) and rape (B.chinensis var. oleifera) seeds were used as experimental materials, in our test. The purpose was to understand the effects of acid rain on seed germination of various acid-fast plants in acidic deposition area and to determine reasons of growth and decline dynamics of crop population and its yield change. In the meantime, seven simulated acid rain (SAR) solutions of pH 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 and neutral solution (pH6.5) as control group (CK) were used. Pretreatment seeds for the three species were placed in culture dishes with filter sheets to germinate in a culture container kept at a constant temperature of 25℃. Each treatment group involved in three dishes and each dish received 50 seeds. During germination, seeds were exposed to simulated acid rain freshly prepared everyday. The germination indexes (activity of POD, content of MDA) were all studied under acid rain stress in both experiments. The results showed that at the 7th day, the activity of POD of the three seeds increased at lower acidity levels, and then decreased at higher acidity levels, but the content of MDA increased always along with the increase of the stress strength. In this time, the second index of different acidity level was higher than that of CK. Compared with CK, the amplitude of the content of MDA was found: rice (13.4%) <wheat (213.7%) <rape (324.5%). The responses on acid rain stress of activity for POD and content of MDA of the three species indicated that there was a acidity level significant difference of each index at P<0.05 at the 7th day,i.e rice (no significant difference)>wheat (3.0)>rape(4.0). The experiment data further evidenced that plants could display different sensitivity under the acid rain stress, in which rice had stronger resistance than wheat, and rape was more susceptible to acid rain than rice and wheat. During 3~7 d, the results proved that the changing curves of each physiological topics were not identical. However, as time went on, all of the POD activity increased with different degrees, and the content of MDA also showed the same increase trend. On the other hand, the protective effect was related with acidity levels. Namely, at the same stress time, POD activities of all control groups of rape and wheat seeds were higher than those of CK, and increased along with the acidity levels. But POD activities of rice seed increased at the lower levels,and then decreased at higher levels.However, the content of MDA of three seeds increased always.It may be concluded that the response of the plants tested in the study was in an order with rice >wheat>rape.