温光处理对节瓜幼苗光合作用的影响

试验以江心4号节瓜为试材,研究了温光处理对节瓜苗期叶片光合作用的影响,结果表明:低温导致了叶片光合色素含量明显降低,且随处理时间的延长而下降;低温下强光促进光合色素含量降低。低温处理下叶绿素a/叶绿素b比值明显提高,且随处理时间的延长而上升。低温下叶绿体类囊体解体、排列无序、联结断开,基粒片层肿涨,淀粉粒、质体球增加,淀粉粒体积变大;持续低温强光导致了叶绿体膜的解体;常温弱光下类囊体排列混乱、质体球增加。低温下叶片Fv/Fm明显下降,低温下强光明显降低Fv/Fm。低温、强光都会造成Fv/Fo的下降,而且低温和强光存在互作。低温下乙醇酸氧化酶活性上升,低温下强光增强了乙醇酸氧化酶活性,低温下较强的光呼吸有利于防御低温光抑制造成的伤害。

Effect of Temperature and Light Treatments on Photosynthesis of Chiehqua Seedlings

Effects of temperature and light treatment on leaf photosynthesis in Chiehqua(Benincasa hispida Cogn var.Chieh-qua How.)seedling(cv.Jiangxin 4) were studied.The results showed that photosynthetic pigments contents decreased under lower temperature.And with the treatment delayed,pigments contents decreased more.Under low temperature,pigment contents de-creased by higher light intensity.The ratio of chlorophyll a/b increased under low temperature,and increased more with the treatment delayed.In chloroplast under low temperature treatment,thylakoid was in disorder and coupling disconnect,the stroma lumen swelled,the number of the starch grain and plastoglobule increased and the starch grain enlarged.The damage of the chloroplast enhanced by lasting higher light intensity and low temperature treatments.However at normal temperature chloroplast ultrastructure was damaged by low light intensity,in which thylakoid was in disorder and plastoglobule increased.The Fv/Fm in leaves decreased obviously under low temperature,and the decrease were enhanced by higher light intensity.While the activities of the glycolate oxidase increased under lower temperature,and enhanced by higher light intensity.The higher photorespiration activity was helpful to the alleviation of the photoinhibition at low temperature.