持续低温弱光对黄瓜叶片气体交换、叶绿素荧光猝灭和吸收光能分配的影响

持续常温弱光(25℃/18℃,l00umol m-2 s-1)、低温弱光(12℃/12℃,100 umol m-2 s-1和7℃/7℃,l00μmolm-2s-1)均导致黄瓜生长减慢或停滞、叶绿素含量、气孔导度和净光合速率、光合电子传递速率下降以及胞间CO2浓度上升.常温弱光和12℃弱光处理对光系统II的最大光化学效率Fv/Fm无显著影响,而7℃弱光处理导致Fv/Fm的可逆性下降.常温弱光和7℃、12℃弱光处理均导致了光化学反应速率的降低以及天线热耗散和反应中心过剩能量的增加.在胁迫后,12℃弱光0比7℃弱光更有利于植株光合功能的恢复.

Effects of Sustained Chilling and Low Light on Gas Exchange,Chlorophyll Fluorescence Quenching and Absorbed Light Allocation in Cucumber Leaves

Exposure of cucumber plants to low light (25 degrees C/18 degrees C, 100 micromol m(-2) s(-1)) and low temperature (12 degrees C/12 degrees C, 100 micromol m(-2) s(-1); 7 degrees C/7 degrees C, 100 micromol m(-2) s(-1)) resulted in a retardation or complete inhibition of plant growth, decreases in chlorophyll content, net photosynthetic rate, stomatal conductance and photosynthetic electron transport rate, but an increase in intracellular CO(2) concentration. Significant reversible reduction in Fv/Fm was found in plants after chilling at 7, but not in those after chilling at 12 degrees C. Chilling and low light treatment resulted in a decrease in chlorophyll content, followed by a decreased allocation of photons absorbed by PSII antenna to the photosynthetic electron transport and an increased allocation of thermal dissipation and excessive energy. Plant chilled at 12 degrees C showed higher recovery capacity than those chilled at 7 degrees C upon returning to normal conditions.