低温对厚皮甜瓜幼苗光合特性的影响

Effect of Low Temperature on Photosynthetic Properties of Melon Seedlings

在人工控制条件下研究了低温对厚皮甜瓜幼苗光合特性的影响.结果表明:低温(昼15℃/夜5℃)胁迫导致甜瓜幼苗的光合色素含量和叶片光能捕捉下降,可利用光强范围变窄,对CO2的利用效率降低,光合作用的瞬时水分利用效率显著降低.在亚适宜温度(昼20℃/夜10℃)下,制约甜瓜光合作用的主导因素为气孔限制,在胁迫低温下则以非气孔因素为主.气孔限制在降低植物碳同化速率的同时,也提高了水分利用效率.低温条件下,伊丽莎白较黄河蜜具有更高的光合色素含量、更大的光能和CO2利用效率、更强的弱光和低浓度CO2利用能力.甜瓜温室型品种伊丽莎白对低温的适应性优于露地品种黄河蜜.

Plant photosynthesis is one of the most important processes sensitive to low temperature stress. Seedlings of melon （Cucumis rnelo L. ）, cv. Huanghemi and Elizabeth, were employed to investigate the effects of low-temperature on chlorophyll contents and photosynthetic characteristics under controllable conditions in growth chamber. The results indicate that chlorophyll contents, light capture capacity, light and CO2 using efficiencies, water using efficiency of melon leaves decrease significantly under low temperatures. Under suboptimum temperature, photosynthesis in melon is limited mainly by deceased stomata conductance, while the major limiting factor under stressing temperature is non-stomata. Stomata limitation increases water using efficiency in melon but decreases the net photosynthetic rate. In the two cultivars investigated, Elizabeth, the greenhouse adapted cultivar, has higher contents, stronger ability photosynthetic pigment to utilize poor light and low concentrations of CO2, higher light and CO2 using efficiencies, and therefore better adaptation to low temperature than Huanghemi, the main cultivar for open field production.