干旱胁迫与复水对棉花叶片光谱、光合和荧光参数的影响

Responses of Spectral Reflectance,Photosynthesis and Chlorophyll Fluorescence in Cotton During Drought Stress and Rewatering

【目的】明确持续干旱胁迫对棉花叶片光谱、光合和荧光特征的影响,为筛选水分敏感指标提供理论依据。【方法】以转基因抗虫棉银瑞361为试材,采用盆栽控水方式,测定持续干旱与复水条件下棉花叶片光谱、光合和荧光参数。【结果】两年试验结果表明,随着干旱胁迫时间的延长叶片相对含水量(RWC)、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、PSⅡ原初光能转化效率(Fv/Fm)、PSⅡ实际光化学量子产量(ΦPSⅡ)、光化学淬灭系数(qP)、光化学反射指数(PRI)呈下降趋势,气孔限制值(Ls)先上升后下降,非光化学淬灭系数(NPQ)则呈上升趋势,复水后除RWC外,其它指标都未恢复到初始状态。与初始状态相比,Pn、Gs、Tr、Fv/Fm、ΦPSⅡ、qP、PRI在干旱胁迫第4天时,两年平均下降了53.1%、79.9%、66.0%、3.8%、11.0%、5.7%、18.4%;Ls、NPQ在第4天时,两年平均上升了98.1%、28.6%。综合两年数据,只有Pn、Gs、Tr、Ls、Fv/Fm、PRI在第4天时与初始状态差异极显著,与RWC的R2分别为0.7640、0.7058、0.5625、0.3665、0.7319、0.4378。【结论】Pn、Gs、Tr、Ls、Fv/Fm、PRI均能在干旱胁迫初期灵敏地反映棉花叶片水分状况;在持续干旱胁迫中,Pn、Gs、Fv/Fm能更灵敏、准确地反映棉花叶片水分状况。

【Objective】 The objective of this paper was to identify photosynthetic and spectral indicators related to drought stress through analysis of photosynthetic traits and spectral index in cotton（Gossypium hirsutum L.）.【Method】 The transgenic cotton cultivar Yinrui 361 was used as material,leaf spectral reflectance,photosynthesis and chlorophyll fluorescence characteristics were studied by a pot experiment during the continuous drought stress and rewatering.【Result】Two years results indicated that leaf relative water content（RWC）,net photosynthesis（Pn）,stomatal conductance（Gs）,transpiration rate（Tr）,maximal photochemical efficiency of PSⅡ in the dark（Fv/Fm）,actual photochemical efficiency of PSⅡ in the light（ΦPSII）,photochemical quenching coefficient（qP） and photochemical reflectance index（PRI） showed a downward trend along with the prolonging of the drought stress.Stomatal limitation value（Ls） increased at the early time,and then decreased later.While non-photochemical quenching coefficient（NPQ） showed an increasing trend.After rewatering,most parameters could not recover to the initial state except RWC.Compared with the initial state on two-year average,Pn,Gs,Tr,Fv/Fm,ΦPSII,qP and PRI in the 4th day of stress decreased by 53.1%,79.9%,66.0%,3.8%,11.0%,5.7% and 18.4%,respectively.While Ls and NPQ increased by 98.1% and 28.6%,respectively.Among them,only Pn,Gs,Tr,Ls,Fv/Fm and PRI had significant differences between values in the 4th day and the initial state,and R2were 0.7640,0.7058,0.5625,0.3665,0.7319 and 0.4378,respectively.【Conclusion】 It was concluded that Pn,Gs,Tr,Ls,Fv/Fm and PRI could be considered as reliable indicators in cotton leaves at the first stage of drought stress,while Pn,Gs,Fv/Fm can sensitively and accurately reflect the water condition of cotton leaves under continuous drought stress.