花期高温高湿对设施黄瓜叶片光合特性和保护酶活性的影响

Effects of High Temperature and Humidity on Photosynthetic Characteristics and Protective Enzyme Activities of Cucumber Leaves in Greenhouse

以黄瓜品种"津优101"为试材,昼温/夜温设计35℃/25℃,40℃/30℃2个水平,相对湿度设计80%,持续时间设为3、6、9、12 d 4个水平,以昼温/夜温28℃/18℃,相对湿度50%处理作为对照,系统研究了恒定湿度下,高温35~40℃处理不同天数时黄瓜的光合作用以及抗氧化酶活性的变化,以期探究高温高湿环境对黄瓜花期叶片光合特性及保护酶活性的影响。结果表明:在日最高温度35~40℃范围内,随着温度升高处理天数增加,黄瓜的最大光合速率(Pn_(max))、表观量子效率(AQE)、光饱和点(LSP)、气孔导度(Gs)、胞间CO_(2)浓度(Ci)均有所降低,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性在高温处理后有短暂上升,然后随处理天数增加而下降,而光补偿点(LCP)、气孔限制值(Ls)、丙二醛(MDA)含量有所增加。恢复处理14 d后,各指标均向对照组数值靠近。研究证实高温处理会通过气孔限制因素抑制光合反应,也会降低酶促防御系统的活性,导致细胞膜脂过氧化程度加深。黄瓜叶片可以通过适宜气温缓解高温热害造成的伤害,但40℃处理的黄瓜叶片光合反应系统以及抗氧化保护酶活性更难恢复到CK水平。

Taking ‘Jinyou 101’ cucumber as test material, two levels of day/night temperature were designed, which were 35 ℃/25 ℃ and 40 ℃/30 ℃ respectively, and relative humidity design 80%.The duration of temperature and humidity treatment were 3,6,9,12 days.Control was set as day temperature/night temperature 28 ℃/18 ℃,relative humidity 50%.Through the above experiments.The changes of photosynthesis and antioxidant enzyme activities of cucumber under the constant humidity and under the high temperature of 35-40 ℃ for different days were studied, so as to explore the effects of high temperature and high humidity environment on photosynthetic characteristics and protective enzyme activities of cucumber leaves at flowering stage.The results showed that, in the maximum daily temperature 35-40 ℃ ranges and as the temperature increases and the number of treatment days increases, cucumber′s maximum photosynthetic rate(Pn_(max)),apparent quantum efficiency(AQE),light saturation point(LSP),stomatal conductance(Gs),intercellular CO_(2) concentration(Ci) all reduced, and superoxide dismutase activity(SOD),peroxidase activity(POD),and catalase activity(CAT) increased briefly after high temperature treatment, and then decreased with the increase of treatment days, while light compensation point(LCP) and stomata limit value(Ls),malondialdehyde(MDA) increased.After resuming treatment for 14 days, all indexes were close to the values of CK control group.Studies have confirmed that high temperature treatment can inhibit photosynthesis through stoma limiting factors, and also reduce the activity of the enzymatic defense system, lead to a deeper degree of lipid peroxidation of cell membranes.Cucumber leaves can alleviate the damage caused by high temperature heat damage through suitable temperature, but the photosynthetic reaction system and antioxidant protection enzyme activities of cucumber leaves treated at 40 ℃ were more difficult to restore to the CK level.