【摘要】 以番茄幼苗为试材,采用光合测试系统(CIRAS-2)和光纤光谱仪(QE65000),同步测定了不同占空比对0.04Hz和0.40 Hz频闪光照射下番茄叶片光合机构的动态影响。结果表明:与连续光相比,超低频(0.04Hz)不同占空比频闪光照射处理增加了番茄叶片RuBP底物的相对同化负荷(rAC),破坏了RuBP底物消耗与再生间的平衡和缓冲性能,降低了叶绿素荧光的光化学淬灭效率,抑制了光系统中电子传递活性,减少了脉冲驱动形成的同化力(NADPH和ATP),光合碳吸收呈现峰谷振荡的弛豫进程;此外,随着占空比的增加,番茄叶片实际光合光能转化效率(aLCE)呈现迅速上升至趋饱合的变化趋势,其中0.04Hz和0.40Hz频闪光下最大aLCE分别出现在60%和40%占空比下,但是当占空比小于60%,0.40Hz下各占空比的aLCE明显高于0.04Hz下的。更多还原

【Abstract】 The dynamic process of net photosynthetic rate(Pn)accompanied chlorophyll a fluorescence was measured by using portable photosynthesis system(CIRAS-2)and fiber optical spectrometer(QE65000)when tomato leaf was illuminated with different duty cycles of pulsed light(frequencies of0.04 Hz and 0.40 Hz)from lightemitting diodes(LEDs,peak wavelength of about 622nm).The results showed that,the oscillation phenomenon of Pn showed peak-valley type only in 0.04 Hz pulsed light with different duty cycle.With increasing of duty cycle,actual light conversion efficiency(aLCE)gradually increased to maximal value at 40% duty cycle for 0.40 Hz and 60% duty cycle for 0.04 Hz,respectively.However,the higher aLCE associated with lower duty cycle(<60%)was present for 0.04 Hz than 0.40 Hz.Under 0.04 Hz pulsed light illumination with 30%-40% duty cycle,the maximum value of relative variable quantity of assimilatory charge(rAC),which related to RuBP consumption and regeneration,played an important role in its photosynthetic oscillation.Furthermore,the peak size and its emerged time of chlorophyll a fluorescence(CF)gradually reduced and delayed when duty cycle of pulsed light varied from 20% to 80% at 0.04 Hz and 0.40 Hz.Consequently,the duty cycle of pulsed light at lower frequency(e.g.0.04 Hz)directly maintained poorer buffering capacity and storage capacity of RuBP pool,which was regulated by smaller assimilatory power(NADPH and ATP)due to discontinuous electron current drive.Then,the smaller relative quantity and bigger variation rate of RuBP regeneration and consumption determined instability of photosynthetic oscillation in pulsed light.更多还原