模拟酸雨对榉树生理特性的影响

选择2年生国家二级重点保护植物榉树为研究对象,设置4个酸雨梯度(pH值设为2.5、3.5、4.5、5.6,其中pH 5.6为对照),进行为期2.5个月的试验,研究不同强度的模拟酸雨对榉树气体交换参数、叶绿素含量和抗氧化酶活性等的影响。结果表明:随着胁迫酸雨pH值的减小,榉树叶片相对电导率和丙二醛(MDA)含量均升高,且二者呈显著正相关;净光合速率(Pn)、气孔导度(Gs)及蒸腾速率(Tr)均先升后降;胞间CO2浓度(Ci)呈逐渐降低;而气孔限制值(Ls)则逐渐增大;叶绿素a(Chl a)和叶绿素b(Chl b)的含量逐渐降低,但Chl a/Chl b无显著变化;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性呈先升后降的单峰曲线变化,其中pH 3.5处理的SOD活性最大,pH 4.5处理的CAT及POD活性最大。榉树叶片在pH 4.5时Pn值最大,抗氧化酶活性高,受到的伤害小,可以考虑作为华东地区园林绿化物种。

Effects of simulated acid rain on physiological characteristics of Zelkova serrata

Taking 2-year old seedlings of Zelkova serrata, a Chinese second class key protected wild plant as test materials, this paper studied effects of 2.5 months simulated acid rain that included 4 different pH values (2.5, 3.5, 4.5 and 5.6, 5.6 as CK) on the gas exchange parameters, chlorophyll content and antioxidant enzyme activities of Z.serrata seedlings leaves. The results showed that with the decreasing of simulated acid rain pH value, the relative conductivities and malondialdehyde (MDA) content of leaves gradually increased, and there was a significant correlation between them. The net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) all showed a trend of increase first and then decrease, however, intercellular CO2 concentration (Ci) decreased continuously. The stomatal limitation value(Ls) showed an trend of gradual increase. Chl a and Chl b content decreased gradually, while the value of Chl a/Chl b showed no significant difference. The dismutase(SOD), catalase(CAT) and peroxidase(POD) activities were showed a single-peak curve which was firstly increased and then decreased, and the maximum of SOD appeared at pH 3.5, CAT and POD appeared at pH 4.5. The Pn value was the biggest, the antioxidant enzymes was high, and the injuries was small, when Z.serrata were stressed in simulated acid rain of pH 4.5. Therefore, Zelkova serrata can be considered as one of the landscaping species in East China.