丛枝菌根真菌对汞胁迫下水稻叶片生理和光合特性的影响

为了研究AM（arbuscular mycorrhizal，丛枝菌根）真菌在Hg胁迫下对农作物生长的影响，通过温室盆栽试验，分析不同Hg投加量（0、0.1、1.0和2.0 mg/kg）下，接种AM真菌对水稻植株生物量、株高、叶片叶绿素相对含量、膜质过氧化程度、抗氧化酶系活性、光合速率、气孔导度、胞间CO₂、水分利用效率、可溶性糖和可溶性蛋白含量的影响.结果表明:①在不同Hg投加量下，AM真菌均能促进水稻植株生长.②AM真菌接种能提高水稻叶片叶绿素相对含量，增加水稻叶片光合速率.③接种AM真菌后，水稻叶片MDA（malondialdehyde）含量降低，水稻叶片超氧化物歧化酶（superoxide dismutase，SOD）、过氧化氢酶（catalase，CAT）、过氧化物酶（peroxidase）和抗坏血酸过氧化物酶（ascorbate peroxidase，APX）活性均升高.综合显著性分析结果来看，当Hg投加量为0.1 mg/kg时，接种AM真菌后水稻整体长势良好，多项生理指标偏高，说明AM真菌在较低Hg投加量下能促进水稻生长，提高水稻对汞的抗性.研究显示，AM真菌能通过促进水稻光合色素分泌来提高水稻光合作用，同时能提高水稻抗氧化酶活性，维持细胞稳态，缓解汞的毒害作用.总之，AM真菌能增强水稻对汞污染的适应能力，促进植株生长发育，降低汞对水稻造成的毒害及损伤，增强抗逆性，且该作用在较低Hg投加量下表现更加明显. 

Effects of Arbuscular Mycorrhizal fungi on Physiological and Photosynthetic Characteristics of Rice Leaves under Mercury Stress

Pot experiments were conducted in a greenhouse to study the effects of AM fungi on the growth and photosynthesis under Hg stress, based on the effect of AM fungi on biomass, height, chlorophyll relative content, photosynthetic rate, stomatal conductance, intercellular CO₂, water use efficiency, membrane lipid peroxidation, antioxidant enzyme activities soluble sugar and soluble protein content. The results showed that: (1) Under different Hg pollution conditions, AM fungi could promote the growth of rice plants. (2) The photosynthetic rate and chlorophyll were also increased by AM fungus inoculation, and AM fungi could improve the photosynthesis of rice by promoting the secretion of photosynthetic pigments. (3) AM fungi could decrease the content of MDA and reduce the degree of lipid peroxidation of cell membrane. The activities of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase were also increased by AM fungus inoculation, which indicated that AM fungi could improve the activity of antioxidant enzymes, maintain cell homeostasis, and alleviate the toxicity of Hg. The results of significance analysis showed that when the concentration of Hg was 0.1 mg/kg, the overall growth of rice was better, while a number of physiological indexes were on the high side, indicating that AM fungi could promote the growth of rice and improve the resistance of rice under low mercury concentration. In conclusion, AM fungi can enhance the adaptability of rice to mercury pollution, promote plant growth and development, reduce the toxicity and damage of Hg to rice, and enhance the stress resistance. This effect will be more obvious under the condition of low concentration mercury pollution.