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 photosystem Ⅱ (PS Ⅱ),actual photochemical yield (Yield), photochemical fluorescence quenching coefficient (Qp), actual photochemical efficiency (ΦPSⅡ)of PS Ⅱ,alterable fluorescence drop ratio (Rfd)and partition coefficient (α)of excited energy of PS I were decreased with the temperature rising. The initial fluorescence (Fo),excited energy pressure (1 - Qp)of PS Ⅱ , partition coefficient (β) of excited energy of PS Ⅱ ,and partition imbalance (β/α-1)of excited energy between PS Ⅰ and Ⅱ were 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.%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.
展开▼
