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在红光LED频闪光照射下,采用光合测定系统(CIRAS-2)和光纤光谱仪(QE65),同步测定了闪光频率下番茄叶片的净光合速率Pn、气孔导度Gs、胞间二氧化碳浓度Ci和叶绿素荧光信号F的动态响应。随着闪光频率从0.01 Hz向10.00 Hz增加,Pn振荡幅度减小,至0.25 Hz以上时Pn振荡幅度不显著;光合光能转化效率LCE’逐渐上升至0.25 Hz以上时达最大;与光系统Ⅱ光化学活性的初级醌受体暗期再氧化程度或光期再还原程度有关的光脉冲荧光相对变化量Fpcr也从较高水平迅速下降,至0.12 Hz时达最低值,之后较快回升,至0.50 Hz以上趋稳并接近于中等水平,显示出ATP池和NADPH池的较强缓冲能力。频闪光的光期Gs始终维持在较高水平,对外界CO2进入胞间的Ci无显著影响。而频闪光的光→暗期间的光后光合碳吸收衰减或暗→光期间的暗后光合碳吸收再启动过程的相对同化负荷变化量ΔACr在0.10 Hz以上衰减趋0,暗示着核酮糖-1,5-二磷酸(ribulose-1,5-bisphosphate,RuBP)的消耗与再生趋于平衡状态,呈现出较强的RuBP池的缓冲能力。综合分析表明,频闪光下,ATP池、NADPH池和RuBP池呈现出的联合缓冲能力,对光后暗期或暗后光期RuBP的持续再生或再生恢复均有维持效应,从而增加闪光频率即相应缩短暗期和光期,致使光合碳吸收Pn的暗期下降幅度减小和光期上升幅度减少,呈现Pn振荡幅度减小至趋稳的现象。
The net photosynthetic rate (Pn), stomatal conductance (Gs) and intercellular carbon dioxide concentration (Ci) of tomato leaves at flash frequency were measured synchronously with CIRAS-2 and QE65 under the strobe illumination of red LED. Dynamic Response of Chlorophyll Fluorescence Signal. As the flash frequency increased from 0.01 Hz to 10.00 Hz, the amplitude of Pn oscillations decreased and the amplitude of Pn oscillations was not significant above 0.25 Hz. The maximum conversion efficiency of photosynthetic light energy LCE ’reached above 0.25 Hz, Fpcr, the relative change in light pulse fluorescence relative to the extent of photoperoxidation of primary quinone receptors during dark phase reoxidation or photoreduction, also decreased rapidly from a relatively high level to the lowest at 0.12 Hz and then rose faster to 0.50 Steady above Hz and close to mid-level, showing a strong buffering capacity for the ATP and NADPH pools. The stroboscopic Gs of stroboscopic light is always maintained at a high level, and has no significant effect on Ci entering the intercellular space of CO2. However, the relative assimilation load change ΔACr of the photosynthetic carbon assimilation and restart during the light-dark period after photosynthetic carbon absorption decay or dark → dark during the stroboscopic light → decay 0 at 0.10 Hz, suggesting that the ribulose- The consumption and regeneration of ribulose-1,5-bisphosphate (RuBP) tended to be in balance with the buffer capacity of RuBP pool. The comprehensive analysis shows that the combined buffering ability exhibited by ATP pool, NADPH pool and RuBP pool under stroboscopic light has a sustained effect on the sustained regeneration or regeneration of photoperiod RuBP, which increases the flash frequency Corresponding shortening of the dark period and the light period resulted in a decrease in the dark period of photosynthetic carbon absorption Pn and a decrease of the light period, showing the phenomenon that the oscillation amplitude of Pn decreased to stabilize.