红壤水分条件对柑橘叶片质膜透性以及活性氧代谢和保护酶活性的影响

通过盆栽柑橘控制盆内红壤不同含水量处理,研究了不同红壤水分条件对柑橘叶片质膜透性以及活性氧代谢和保护酶活性的影响.结果表明,柑橘叶片相对电导率在红壤相对含水量75% 处理时最低,并与红壤相对含水量呈显著负相关(R2 = 0.8236*,n=50);柑橘叶片丙二醛(MDA)含量随土壤水分含量的减少而显著增加,并与红壤相对含水量呈显著负相关(R2 = 0.9051*,n=50).柑橘叶片超氧阴离子自由基(O2.-)生成速率与过氧化氢(H2O2)含量在不同红壤水分条件下具有相近的变化曲线,在红壤相对含水量60% 的处理下达最大值后,随红壤水分减少或增加均呈下降趋势;O2.-、H2O2并不是引起柑橘在红壤水分亏缺或盈余胁迫状况下氧化伤害的单一原因.随着红壤含水量的变化,柑橘叶片抗氧化系统处于动态的平衡中,柑橘叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)酶活性在红壤干旱条件下都保持了较高的活性,但过氧化氢酶(CAT)活性随土壤水分减少却显著降低.

Effects of Red Soil Moisture on Content of Reactive Oxygen Species and Activities of Protective Enzymes of Citrus (Citrus Unshiu Marc.) Leaves

The cytoplasm membrane permeability (CMP), reactive oxygen species (ROS) and the activities of protective enzymes (APX, CAT, POD and SOD) of citrus (Citrus unshiu Marc.cv.) leaves under different red soil moisture treatments (levels) were studied. The results showed that malondialdehyde (MDA) and CMP of citrus leaves increased evidently and superoxidation of lipid metabolism also aggravated as soil relative water content (SWC) reduced. Both MDA content and CMP were significantly correlated with SWC (R2 = 0.9051* and 0.8236*, n = 50, respectively). Both superoxide anion radical (O2.-) producing rate and H2O2 content reduced with the decrease of soil water content. However, this was not the single reason that O2.- and H2O2 led to the oxidative damage of citrus leaves under red soil drought conditions. The anti-oxidation system of citrus leaves was in the homeostasis as SWC changed. The activities of SOD, POD and APX remained high under the deficit of soil water, while CAT activity decreased rapidly with the decrease of SWC.