酸雨对生菜的光合、抗氧化系统和产量的影响研究

目前国内外有关酸雨对植物生长危害的影响研究多集中在森林植物和粮食作物,而酸雨对叶菜类蔬菜生长的相关研究较少。酸雨的频发可能会影响蔬菜的生长,进而降低蔬菜产量。为探究酸雨对叶菜类蔬菜生理和产量的影响,选取生菜(Lactuca sativa L.var.ramosa Hort.)作为试验材料,采用野外原位研究方法,探究模拟酸雨(pH梯度为3.0、4.0、5.0)和自然降水(CK)对生菜光合、抗氧化系统和产量的影响。结果表明,pH 4.0和5.0酸雨对生菜光合系统影响不显著,pH 3.0酸雨对生菜光合系统影响显著;在整个试验期内,pH 3.0酸雨显著降低生菜净光合作用8.4%—17.0%。pH 3.0、4.0和5.0酸雨均显著提高生菜超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量,表明酸雨会激活生菜抗氧化系统,同时会对生菜叶片膜系统造成损伤;在第20天后,pH 3.0酸雨下生菜过氧化氢酶(CAT)活性显著下降13.8%%—35.2%。pH 5.0酸雨对生菜产量影响不显著;pH 4.0和3.0酸雨显著降低生菜地上部产量,分别降低14.6%和16.7%。pH 3.0酸雨使生菜地下部产量显著降低19.0%。综上可见,模拟酸雨对生菜的光合系统、抗氧化酶系统和产量均产生显著影响,且酸雨对生菜的影响阈值在pH 4—5之间,pH 4.0以下的酸雨明显降低生菜产量,但酸雨强度为pH 5.0时已存在生菜减产的风险,研究结果可为生菜栽培的相关农户以及决策部门提供参考。

Study on the Effects of Acid Rain on the Photosynthetic and Antioxidant Systems and Yield of Lettuce

At present,the domestic and foreign research on the impact of acid rain on plant growth mainly focuses on forest plants and field food crops,and there is little study on the growth of vegetables under acid rain stress.Vegetables play an important role in human diet structure.With the improvement of people’s living standards,the demand for vegetables is increasing.The frequent occurrence of acid rain may affect the growth of vegetables and reduce their yield.In order to explore the impact of acid rain on the physiological and growth effects of lettuce(Lactuca sativa L.var.ramosa),this study investigated effects of simulated acid rain(pH gradients of 3.0,4.0 and 5.0)and natural precipitation(CK)on photosynthesis,antioxidant system and yield of lettuce.The results showed that pH 4.0 and 5.0 acid rain had no significant effect on the photosynthetic system of lettuce.However,pH 3.0 acid rain significantly reduced the relative chlorophyll content and net photosynthesis of lettuce.During the whole experiment period,acid rain at pH 3.0 significantly reduced net photosynthesis of lettuce by 8.4%?17.0%.pH 3.0,4.0 and 5.0 acid rain significantly increased the activity of superoxide dismutase(SOD)and malondialdehyde(MDA)of lettuce,indicating that acid rain activated the antioxidant system and caused damage to the membrane system of lettuce leaves.After the 20th day,the catalase(CAT)activity of lettuce significantly decreased by 13.8%?35.2%under pH 3.0 acid rain.Acid rain at pH 5.0 had no significant effect on lettuce yield,but pH 4.0 and 3.0 treatments significantly reduced lettuce aboveground yield by 14.6%and 16.7%,respectively.Moreover,pH 3.0 acid rain produced a significant 19.0%reduction in lettuce underground yield.In conclusion,simulated acid rain had an impact on the photosynthetic system,antioxidant enzyme system and yield of lettuce,and acid rain reduced the yield of lettuce by affecting the photosynthetic system and antioxidant system.In addition,this study showed that the tolerance threshold of lettuce to acid rain was basically between pH 4 and 5.Acid rain below pH 4.0 significantly reduced the yield of lettuce,but when the intensity of acid rain was pH 5.0,there was still a risk of lettuce yield reduction.These findings can provide references for farmers and decision-making departments engaging in lettuce cultivation.