pH环境对香椿幼苗生长、光合作用和生理特性的影响

Effects of different pH environments on the growth, photosynthesis and physiological characteristics of Toona sinensis seedlings

【目的】为香椿育苗基质配置和苗圃地、造林地选择提供参考。【方法】以香椿2年生幼苗为材料进行盆栽试验,探究不同pH(3.0、4.0、5.0、6.0、7.0、8.0、9.0、10.0)环境对香椿幼苗生长、光合作用、细胞膜透性、渗透调节物质含量及抗氧化酶活性的影响。【结果】强酸(pH≤4.0)和强碱(pH≥9.0)胁迫对香椿幼苗生长具有抑制作用,地径增长量、苗高增长量、复叶长度和小叶面积随pH增大总体表现出先升高后下降的规律。地径增长量和苗高增长量在pH为3.0~6.0和9.0~10.0时极显著低于pH为7.0、8.0的处理和对照;复叶长度和小叶面积在pH为6.0~8.0时受影响不显著,其他处理极显著低于对照。随着pH增加,香椿幼苗叶片的净光合效率、气孔导度和蒸腾效率均呈现先增加后下降的变化规律,pH为3.0、4.0、10.0时均极显著低于其他处理;叶片胞间CO_(2)浓度整体呈现先下降后增加的趋势,在pH为7.0时其浓度最低。叶片细胞膜透性、MDA含量、SOD活性、POD活性和渗透调节物质含量随pH增加呈现先降低后升高的趋势,但各指标的变幅存在差异,且酸胁迫比碱胁迫的影响更大。在pH≤5和pH≥9环境下,香椿幼苗叶片的细胞膜均受到了不同程度的破坏,在强酸强碱环境下细胞膜受损更为严重。【结论】香椿幼苗生长受到pH环境影响,酸、碱环境导致叶片细胞膜透性增大、抗氧化酶活性增强以及光合作用减弱,酸胁迫比碱胁迫对香椿幼苗生长的抑制作用更显著。香椿幼苗有一定耐酸碱能力,生长适宜pH为6.0~8.0。

【Objective】Provide reference for configuring the matrix of Toona sinensis seedling cultivation and selecting nursery and afforestation sites.【Method】Using 2-year-old T.sinensis seedlings as materials,potted experiments were conducted to investigate the effects of different pH environments(3.0,4.0,5.0,6.0,7.0,8.0,9.0,10.0)on the growth,photosynthesis,cell membrane permeability,osmotic regulation substance content,and antioxidant enzyme activity of T.sinensis seedlings.【Result】Strong acids(pH≤4.0)and strong alkalis(pH≥9.0)stress had inhibitory effects on the growth of young T.sinensis seedlings.The growth increments of stem diameter,seedling height,compound leaf length,and leaf area generally show a pattern of first increasing and then decreasing with increasing pH;the growth increments of stem diameter and seedling height were significantly lower at pH 3.0-6.0 and 9.0-10.0 than those at pH 7.0,8.0 treatments,and the control;compound leaf length and leaf area were not significantly affected at pH 6.0-8.0,but significantly lower in other treatments compared to the control.As the pH increased,the net photosynthetic efficiency,stomatal conductance, and transpiration efficiency of young T. sinensis seedlings showed a pattern of first increasing and then decreasing. At pH 3.0, 4.0, and 10.0, these values were significantly lower compared to other treatments. The intercellular CO_(2)concentration of the leaves overall showed a trend of first decreasing and then increasing, with the lowest concentration at pH 7.0. The leaf cell membrane permeability, MDA content, SOD activity, POD activity, and osmotic regulation substance content all showed a trend of decreasing first and then increasing with increasing pH, but the magnitude of change varied among these indicators, and the impact of acid stress was greater than that of alkaline stress. In environments with pH ≤ 5 and pH ≥ 9, the cell membranes of T. sinensis seedlings were both damaged to varying degrees. The cell membranes were more severely damaged in strong acid and alkali environments.【Conclusion】The growth of T. sinensis seedlings is affected by the pH value of the environment. Acidic or alkaline conditions cause an increase in leaf cell membrane permeability, enhanced antioxidant enzyme activity, and weakened photosynthesis. Acid stress has a more significant inhibitory effect on the growth of T. sinensis seedlings compared to alkaline stress. T. sinensis seedlings have a certain tolerance to acidity and alkalinity, with the optimal pH range for growth being 6.0 to 8.0.