黄瓜幼苗光合及荧光特性对弱光的响应

Effects of Low Light on Photosynthetic and Fluorescent Characteristics of Seedlings of Cucumis sativus

以不耐弱光的‘津研2号’和较耐弱光的‘戴多星’黄瓜(Cucumis sativus L.)为试材,在人工气候室内研究其光合及荧光特性对弱光(75～85μmol·m^(-2)·s^(-1))的响应。结果表明,弱光处理后叶片光合色素含量、总叶绿素/类胡萝卜素比值呈增加趋势,尤其是戴多星更明显;叶绿素a/b比值呈减小趋势,且戴多星的减小幅度大于津研2号;净光合速率、水分利用效率呈下降趋势,戴多星下降幅度小于津研2号;叶片最大光化学效率、光系统Ⅱ实际光化学效率、光化学反应速率、光系统非环式电子传递速率、光系统Ⅱ吸收光能用于光化学反应的比例,对弱光的响应有一定差异,弱光下戴多星均有明显增加,而津研2号的增减不规律,且幅度均较小,说明弱光下戴多星对弱光的利用能力明显强于津研2号。

The effects of low light on photosynthetic and fluorescent characteristics of seedlings of Cucumis sativus （ shade susceptible ‘ Jinyan 2＇ and shade tolerant ‘ Dehastar＇ ） were investigated in the growth chamber. After 20 days of treatment under low light intensity （75 -85 mol · m^-2 · s^-1 ） , the photosynthesis pigment contents and the ratios of chlorophylls/carotenoids [ Chl. （ a ＋ b） /Car. ] in leaves of the two cuhivars increased, and the values were higher in ‘ Deltastar＇ than in ‘ Jinyan 2＇. While, the ratios of Chl. a/b decreased, especially in ‘ Dehastar＇. The net photosynthesis rate （Pn） and water use efficiency in the two cuhivars decreased but the smaller reduction extents and higher values were observed in ＇ Deltastar＇. There were some differences in effects of low light on the maximal photochemical efficiency of PS Ⅱ in the dark （ Fv/ Fm） , the actual photochemical efficiency of PS Ⅱ in the light （ ФPS Ⅱ） , the photochemical reaction rate （Prate） , the linear whole-chain electron transport rate and the partitioning proportion for photochemical reaction of light energy absorbed by PS Ⅱ between the two eultivars, which increased markedly in ‘ Dehastar＇ , while less changes were obsearved in‘Jinyan 2＇. It indicated that light energy use capability in ‘ Dehastar＇ was stronger than that in ‘Jinyan 2＇ under low light.