铜胁迫条件下土壤微生物对海州香薷光合特性和叶绿素荧光参数的影响

为探讨铜（Cu）胁迫条件下土壤微生物对海州香薷（Elsholtzia splendens）光合生理和叶绿素荧光参数的影响，实验设置添加Cu（Cu胁迫）、接种土壤微生物、添加Cu与接种土壤微生物等3个处理，以不添加Cu与不接种土壤微生物为对照（CK）。结果表明：接种土壤微生物处理的植株相对叶绿素含量、净光合速率（P_n）、水分利用效率（WUE）均显著高于CK；且对初始荧光（F_o）和最大光化学效率（F_v/F_m）均有显著性影响。与CK相比，添加Cu降低了海州香薷的P_n和气孔导度（G_s），但胞间CO₂浓度（C_i）的变化与P_n相反，表明其对光合作用的影响主要是非气孔限制因素。添加Cu的植株相对叶绿素含量显著下降，但Cu胁迫下接种土壤微生物提高了植株相对叶绿素含量，差异显著。在Cu胁迫条件下，接种土壤微生物的植株具有较高的F_v/F_m及较低的F_o，显著提高了海州香薷的WUE、P_n、G_s。说明接种土壤微生物可通过提高相对叶绿素含量、改善叶绿素荧光和光合作用来减轻Cu胁迫对海州香薷植株造成的伤害，从而提高海州香薷耐受Cu胁迫的能力。

Effects of Soil Microbes on Photosynthetic Characteristics and Chlorophyll Fluorescence Parameters of Elsholtzia splendens under Copper Stress Condition

To determine the effects of soil microbes on the photosynthetic and physiological responses as well as the chlorophyll fluorescence parameters of Elsholtzia splendens, four soil treatments were analyzed in this experiment: the addition of copper (copper stress); a soil microbes inoculation; addition of copper and soil microbes inoculation; and no additional copper or soil microbes inoculation (CK). The results showed that the net photosynthetic rates (P_n), relative chlorophyll content, and water use efficiency (WUE) of E.splendens inoculated with the soil microbes were higher than those in the CK, and the differences among the various treatments were significant. There was a significant impact on the minimal fluorescence (F_o) and maximal efficiency of PSⅡ photochemistry (F_v/F_m). In comparison with CK, the additional copper treatment reduced P_n and stomatal conductance (G_s), but the intercellular CO₂ concentration (C_i) increased, which was mainly due to a non-stomatal limitation. The addition of copper was found to reduce the relative chlorophyll content, but the soil microbes inoculation could increase it, and the difference between the treatments was significant. Soil microbes inoculated plants had higher F_v/F_m and F_o under copper stress. The P_n, WUE, and G_s of E.splendens inoculated with the soil microbes increased markedly. It was suggested that soil microbes inoculation could alleviate copper stress on E.splendens plants by improving the relative chlorophyll content, photosynthesis, and chlorophyll fluorescence of leaves.