不同灌溉模式下CO_(2)浓度升高对玉米幼苗生理特性的影响

Effects of CO_(2) enhancement on physiological characteristics of maize seedlings under different irrigation strategies

为了揭示不同灌溉模式下CO_(2)浓度升高对玉米幼苗生理特性的影响,深入分析了充分灌溉、交替灌溉与亏水灌溉模式下CO_(2)浓度升高对内源激素含量、光合与叶绿素荧光、活性氧积累及抗氧化机制的影响。结果表明:交替与亏水灌溉均能够促进脱落酸/玉米素核苷(ABA/ZR)升高,进而诱导气孔收缩。这大幅降低了蒸腾,但仅在一定程度上降低了交替灌溉模式下的光合碳同化。最终,交替灌溉诱导了幼苗叶片水分利用效率(WUEleaf)的升高,且其维持了幼苗最大光化学效率(F_(v)/F_(m))的稳定。气孔收缩还进一步诱导了叶片O_(2)^(·-)与H_(2)O_(2)的大量生成;交替灌溉能够通过提高叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)与过氧化氢酶(CAT)等抗氧化酶活性,维持丙二醛(MDA)含量稳定,从而避免了膜脂过氧化伤害。CO_(2)浓度升高降低了各灌溉模式下的ABA/ZR,加快了电子传递、升高了光合速率(Pn)与WUEleaf。此外,CO_(2)浓度升高还在一定程度上抑制了各灌溉模式下叶片O_(2)^(·-)与H_(2)O_(2)的生成,叶片SOD、CAT与POD等抗氧化酶活性相应降低。最终,CO_(2)浓度升高降低了各灌溉模式下膜脂过氧化程度,从而有利于作物的生长。

In order to reveal the effects of CO_(2)enhancement on the physiological characteristics of maize seedlings under different irrigation strategies,the effects of CO_(2)enhancement on endogenous hormone content,photosynthesis and chlorophyll fluorescence,reactive oxygen species accumulation and antioxidant mechanism under sufficient irrigation,alternating irrigation and water deficit irrigation were analyzed.The results showed that,alternative and deficit irrigation promoted the increase of abscisic(ABA)/zeatin-riboside(ZR),and then induced stomatal contraction,which significantly reduced transpiration,but only reduced photosynthetic assimilation under alternative irrigation in a certain extent.Finally,alternating irrigation induced the increase of leaf water use efficiency and maintained the stability of maximal efficiency of PSⅡ(F_(v)/F_(m)).Stomatal contraction also induced excess generation of O_(2)^(·-) and H_(2)O_(2) in leaves.Alternative irrigation could maintain the stability of malondial-dehyle(MDA)content by increasing the activity of leaf antioxidant enzymes including catalase(CAT),peroxidase(POD),and superoxide dismutase(SOD),so as to avoid the possible damage of membrane lipid peroxidation.The enhancement of CO_(2)concentration decreased ABA/ZR,accelerated electron transfer rate,increased photosynthetic rate and leaf water use efficiency.In addition,the enhancement of CO_(2)concentration inhibited the generation of O_(2)^(·-) and H_(2)O_(2) in leaves under different irrigation strategies in a certain extent,and the activities of leaf antioxidant enzymes,such as SOD,CAT and POD,decreased accordingly.Finally,the enhancement of CO_(2)concentration reduced the level of membrane lipid peroxidation under different irrigation strategies,which is conducive to crop growth.