高温胁迫对不同类型黄瓜幼苗叶绿素荧光特性的影响

研究了5个不同类型黄瓜自交系幼苗在高温胁迫(昼温38℃/夜温28℃,昼温42℃/夜温32℃)下的热害指数和叶绿素荧光参数的变化。结果表明:高温胁迫下,最大荧光(Fm)、光系统Ⅱ(PSⅡ)最大光化学效率(Fv/Fm)、实际光化学量子产量(Yield)、光化学荧光淬灭系数(qP)、光系统Ⅱ实际光化学效率(ΦPSⅡ)、可变荧光下降比值(Rfd)和光系统Ⅰ激发能分配系数(α)均随着胁迫温度的升高而降低;初始荧光Fo、光系统Ⅱ激发能压力(1-qP)、光系统Ⅱ激发能分配系数(β)和光系统Ⅰ和Ⅱ间激发能分配的不平衡性(β/α-1)则随着胁迫温度的升高而升高。表观光合电子传递速率(ETR)在38℃高温下迅速上升,42℃高温下则急剧下降。相关性分析表明:Yield、ETR与热害指数呈显著的负相关关系,可以作为黄瓜幼苗期耐热鉴定的可靠指标。

Effects of high temperature stress on chlorophyll fluorescence characteristics of different-type cucumber seedlings

Seedlings of 5 different-type cucumber inbred lines under high temperature stress(day 38℃/night 28℃and day 42℃/night 32℃)were investigated in terms of heat injury index and chlorophyll fluorescence parameters.The results indicated that under high temperature stress,the maximum fluorescence(Fm),maximum photochemical efficiency(Fv/Fm)of photosystemⅡ(PSⅡ),actual photochemical yield(Yield),photochemical fluorescence quenching coefficient(qP),actual photochemical efficiency(ΦPSⅡ)of PSⅡ,alterable fluorescence drop ratio(Rfd)and partition coefficient(α)of excited energy of PSⅠwere decreased with the temperature rising.The initial fluorescence(Fo),excited energy pressure(1-qP)of PSⅡ,partition coefficient(β)of excited energy of PSⅡ,and partition imbalance(β/α-1)of excited energy between PSⅠandⅡwere increased with the temperature rising. The apparent electron transport rate(ETR)was rapidly increased after 38℃treatment but sharply decreased after 42℃treatment.The correlation analysis showed that the Yield and ETR had a significant negative correlation with the heat injury index and could be used as reliable indexes to determine the heat tolerance of cucumber at seedling stage.