镁对温室黄瓜光合特性的影响

在温室无土栽培条件下研究了镁对黄瓜开花结果期光合特性的影响。结果表明，多镁胁迫增加了黄瓜叶片叶绿素a、叶绿素b含量，降低了 胡萝卜素含量，缺镁胁迫使黄瓜叶片叶绿素a、叶绿素b、胡萝卜素含量均极显著降低，但缺镁胁迫的叶绿素a/b最高；缺镁胁迫下黄瓜叶片净光合速 率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）的日变化呈单峰曲线变化，而多镁胁迫下Pn和Tr呈双峰曲线；多镁和缺镁胁迫的胞间CO₂浓度（Ci）、 多镁胁迫的Gs呈近似倒抛物线型；多镁和适镁处理叶片的光饱和点、CO₂饱和点以及表观量子效率和羧化效率都大于缺镁处理。缺镁胁迫下黄瓜光合 作用主要是受非气孔限制,而多镁胁迫下气孔因素和非气孔因素二者兼具。

Effects of Magnesium Stress on Photosynthetic Character of Cucumber in Greenhouse

The effects of magnesium stress on photosynthetic character of cucumber were studied in greenhouse and under soilless condition.The results showed that the contents of chlorophyll a,chlorophyll b were inecreased,and carotenoids content decreased under Mg-excessive,the contents of chlorophyll a,chlorophyll b and carotenoids were extremly significantly decreased under Mg- deficiency.Net photosynthesis rate（Pn）,stomata conductance（Gs）and transpiration rate（Tr）changed in one peak curve under Mg-deficiency，Pn and Tr changed in double peak curve under Mg-excessive.Ci under Mg-excessive and Mg-deficiency,Gs under Mg- excessive changed in inverted parabolic curve in daytime.Light saturation point，CO₂ saturation point,apparent quantum yield and carboxylation efficiency under Mg-excessive and Mg-optimum are higher than Mg-deficiency.The main limiting factor of photosynthesis of cucumber seedling is non-stomata factors under Mg-deficiency.They were both stomata and non-stomata factors under Mg-excessive.