酸雨胁迫对缙云山马尾松幼苗光合生理特性的影响

Effects of Acid Rain Stress on Photosynthetic Physiological Characteristics of Pinus massoniana Seedlings in Jinyun Mountain

缙云山位于我国的西南酸雨区,近年来酸雨的酸性和频率越来越高,同时也存在硫酸型酸雨向硫酸-硝酸混合型及硝酸型酸雨转变的趋势。研究酸雨类型的转变对缙云山植被光合生理特性的影响,为酸雨受灾区的植被建设和抗酸树种的培育提供基础数据。以缙云山两年生马尾松幼苗为研究对象,通过4个月的盆栽实验的方法对幼苗进行了3种酸雨类型(硫酸型、硝酸型和混合型)和3个酸雨浓度(pH2.5、pH3.5、pH4.5)的处理,并辅以pH值为5.7的蒸馏水作为对照组,对植物的净光合速率、胞间CO;浓度、气孔导度、蒸腾速率、抗氧化酶活性、叶绿素含量和丙二醛含量进行测定。结果表明:(1)3种酸雨对马尾松的光合生理特性都产生了影响,酸雨浓度越高对光合速率的抑制作用越明显;pH3.5是影响马尾松各指标发生急剧变化的酸度值,pH值为3.5的SAR和NAR酸雨对马尾松的株高增长产生严重抑制,抑制率高达53.49%和54.99%。(2)不同类型酸雨胁迫会抑制马尾松叶片叶绿素的形成主要表现为SAR>NAR>MAR,叶绿素含量随酸雨浓度升高而下降;酸雨能够促进丙二醛含量的增加,pH值越低丙二醛含量越高。(3)酸雨会刺激植物叶片抗氧化酶活性,不同酸雨对叶片抗氧化酶活性均产生不同程度的影响,表现为NAR>SAR>MAR。这3种类型酸雨对马尾松幼苗的光合生理特性均有影响,且不同类型酸雨各梯度下影响程度均不同,综合比较发现MAR酸雨的抑制作用较其他两种单一酸雨要小,NAR酸雨对马尾松的影响最大。

Jinyun mountain is located in the acid rain area of southwest China.In recent years,the acidity and frequency of acid rain are getting higher and higher,and there is also a trend of transformation from sulfuric acid rain to sulfuric acid-nitric acid mixed rain and nitric acid rain.The effects of acid rain type change on photosynthetic and physiological characteristics of vegetation in jinyun mountain were studied to provide basic data for vegetation construction and cultivation of acid-resistant tree species in disasterareas.Two years of Pinus massoniana seedling in jinyun mountain were treated with three acid rain types(sulfuric acid,nitric acid and mixed),and three acid concentration(pH2.5,pH3.5,pH4.5)processing by pot experiment for four months,supplemented by the pH value of 5.7 distilled water as control group,the net photosynthetic rate,intercellular carbon dioxide concentration,transpiration rate,stomatal conductance,antioxidant enzyme activity,chlorophyll content and malondialdehyde content were determined.The results showed that:(1)The three kinds of acid rain had effects on the photosynthetic physiological characteristics of Pinus massoniana.The higher the concentration of acid rain,the more obvious the inhibition effect on the photosynthetic rate.The pH value of 3.5 was the acid value that affected the sharp changes of all indexes of Pinus massoniana.SAR and NAR acid rain with pH value of 3.5 had serious inhibition on the growth of Pinus massoniana plant height,and the inhibition rates were as high as 53.49% and 54.99%.(2)Different types of acid rain stress inhibited the formation of chlorophyll in Pinus massoniana leaves,and the main expression was SAR>NAR>MAR.The chlorophyll content decreased with the increase of acid rain concentration.Acid rain can promote the increase of malondialdehyde content,and the lower the pH value,the higher the content of malondialdehyde.(3)Acid rain could stimulate the activity of antioxidant enzymes in plant leaves.Different acid rain had different effects on the activity of antioxidant enzymes in leaves,which showed NAR>SAR>MAR.The three types of acid rain all had effects on the photosynthetic physiological characteristics of Pinus massoniana seedlings,and the effects of different types of acid rain were different under different gradiens.By comprehensive comparison,it was found that MAR acid rain had less inhibitory effect than the other two single acid rain,and NAR acid rain had the largest effect on Pinus massoniana seedlings.