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研究了150mmol·L-1NaHCO3胁迫下,不同浓度硝酸镧对黑麦草幼苗光合作用、叶绿素荧光参数、Mehler反应,以及叶黄素循环的影响.结果表明:低浓度硝酸镧(0.05mmol·L-1)叶面喷施处理能显著减小NaHCO3胁迫下黑麦草叶片净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、气孔限制值(Ls)的下降幅度和胞间CO2浓度(Ci)的上升幅度,有效缓解NaHCO3胁迫对叶片PSⅡ光化学猝灭(qP)、实际光化学效率(ΦPSⅡ)、依赖光合碳同化电子传递(ETRp)和依赖Mehler反应电子传递(ETRm)的抑制,增强黑麦草叶片中超氧化物歧化酶、过氧化物酶和抗坏血酸过氧化物酶的活性,提高非光化学能量耗散(NPQ)、叶黄素循环库(V+A+Z)和脱环氧化程度(A+Z)/(V+A+Z),从而减轻NaHCO3胁迫对光合机构的伤害;但高浓度硝酸镧(0.5mmol·L-1)对NaHCO3胁迫伤害的缓解效果不明显.表明适宜浓度的硝酸镧能够缓解NaHCO3胁迫下非气孔因素引起的黑麦草叶片光合速率下降以及对光化学效率的抑制,并通过促进Mehler反应直接耗散过剩激发能和激活依赖叶黄素循环的热耗散,保护NaHCO3胁迫引起的过剩光能对光合机构造成的伤害,而Mehler反应加强所产生的活性氧可被抗氧化酶活性的提高所清除.
The effects of different concentration of lanthanum nitrate on the photosynthesis, chlorophyll fluorescence parameters, Mehler reaction and lutein cycling of Lolium perenne L. were studied under the stress of 150 mmol·L-1NaHCO3 stress.The results showed that Lanthanum nitrate (0.05 mmol·L-1) ) Foliar application significantly reduced the decrease of net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), stomatal limitation value (Ls) and intercellular CO2 concentration (Ci), and effectively alleviated the effects of NaHCO3 stress on photochemical quenching (qP), actual photochemical efficiency (ΦPSⅡ), inhibition of photosynthetic carbon assimilative electron transfer (ETRp) and Mehler electron transport (ETRm) The activities of superoxide dismutase, peroxidase and ascorbate peroxidase in leaves of ryegrass increased the non-photochemical energy dissipation (NPQ), the lutein cycle library (V + A + Z) and the degree of de-epoxidation (A + Z) / (V + A + Z), so as to alleviate the damage of photosynthetic apparatus by NaHCO3 stress. However, the effect of 0.5 mmol·L-1 Lanthanum on the NaHCO3 stress injury was not obvious, Lanthanum nitrate can alleviate the non-stomata-induced rye under NaHCO3 stress The decrease of photosynthetic rate of leaves and the inhibition of photochemical efficiency and protect the photosynthetic apparatus from the excess light energy caused by NaHCO3 stress by directly dissipating the excess excitation energy and activating the heat dissipation dependent on the lutein cycle through the Mehler reaction, Mehler reaction to enhance the production of reactive oxygen species can be antioxidant enzyme activity increased clearance.