模拟酸雨对玉米种子萌发和幼苗生长的影响

Effects of Simulated Acid Rain on Seed Germination and Seedling Growth of Maize

以中性溶液(pH=7.0)为对照,研究了pH值为1.0、2.0、3.0、4.0、5.0和6.0模拟酸雨对玉米种子萌发和幼苗生长的影响。结果表明:玉米种子萌发和幼苗生长各指标(发芽率、发芽势、发芽指数和活力指数)随着pH值的降低而降低,pH值模拟酸雨胁迫对玉米种子萌发和幼苗生长均产生了一定的抑制作用,随着pH值的降低其抑制作用逐渐增强;弱酸(pH=5.0和pH=6.0)条件下玉米种子能够正常萌发和生长,种子萌发和幼苗生长各指标(玉米幼苗苗长、苗干重、苗干物质分配和根长、根干重、根干物质分配)与对照没有显著差异(P>0.05),表现出一定的耐酸性;在pH值低于5.0时,玉米种子萌发和幼苗生长严重受阻,种子萌发和幼苗生长各指标均显著低于对照(P<0.05);pH值为1.0时,玉米种子失去活性而完全没有萌发;玉米种子浸提液电导率和丙二醛(MDA)含量随pH值的降低呈增加趋势,根系活力(TTC)随pH值的降低呈降低趋势,说明模拟酸雨降低了玉米种子的根系活力。不同pH值模拟酸雨胁迫对玉米幼苗生理指标影响较大,叶绿素含量、类胡萝卜素含量、保护酶(SOD、POD、CAT)和非保护酶(PPO、PAL)活性随酸性的增强呈降低趋势。综合分析认为,玉米种子萌发对pH值模拟酸雨胁迫下的临界值和极限值为3.0~4.0。

In order to study the effects of acid rain on seed germination and seedling growth of maize,the experiment was carried out with simulated acid rain at pH 1.0,2.0,3.0,4.0,5.0,6.0 and 7.0.The results showed that the indexes of seed germination and seedling growth of maize were inhibited and reduced by the decreasing of the pH value.The indexes of seed germination and seedling growth of maizehad no significant difference from CK with the pH value from 5.0 to 6.0(P>0.05)and showed some resistance to acid.When the pH was below 5.0,maize seed germination and seedling growth of maize were sharply inhibited,and the indexes were significantly lower than CK(P<0.05).The maize didn’t shoot up at pH 1.0 at all.The results also showed that different pH simulated acid rain had a large effect on the seedling physiological indexes of maize,the activity of chlorophyll content,carotenoid content,protected enzyme(SOD,POD,CAT)content and the protective enzyme(PPO,PAL)content showed a decreasing trend with the increase of acid,while the relative conductivity and malondialdehyde(MDA)showed an increasing trend.According to the comprehensive results,we can draw the conclusion that the injury threshold value of acid rain was likely between pH 3.0 and pH 4.0.