干旱胁迫对棉花冠层光合、光谱和荧光的影响

Responses of Canopy Photosynthesis, Spectral Indices and Solar-Induced Chlorophyll Fluorescence in Cotton under Drought Stress

【目的】研究干旱胁迫下棉花冠层荧光表现。【方法】以转基因抗虫棉农大601为试材,在田间移动旱棚内,设置4种水分处理(正常、轻度干旱、中度干旱和重度干旱),在群体水平研究了冠层光合速率(CAP)、冠层光谱指数和冠层日光诱导荧光(F761)等指标与植株叶片含水量(LWC)和叶面积指数(LAI)间的关系。【结果】两年试验结果表明:随着干旱胁迫程度的加深,LWC、LAI、CAP、归一化差值植被指数(NDVI)、光化学反射指数(PRI)和F761均呈下降趋势,水分指数(WI)呈上升趋势。经统计分析,重度胁迫下的所有指标与对照差异极显著。NDVI、PRI和WI与LWC、LAI极显著相关,NDVI、PRI和WI与LAI的相关系数(|r|>0.6)均低于它们与LWC的关系(|r|>0.8),F761与LWC、LAI的相关系数高于其它光谱指数。【结论】冠层光合速率、冠层光谱指数和冠层日光诱导荧光均能反映干旱条件下植株含水量和叶面积指数,冠层日光诱导荧光可能比冠层光谱指数更为敏感地反映棉花水分状况。

[Objective] Study canopy photosynthesis, spectral indices and solar-induced chlorophyll fluorescence in cotton under drought stress. [Method] Using transgenic cotton cultivar Nongda 601 as material, a two-year experiment was conducted with four irrigation regimes （CK, light drought, moderate drought and severe drought） under a field mobile shed to measure the fol- lowing indices and parameters at canopy level： canopy photosynthetic rate （CAP）, spectral indices （normalized difference vege- tation index （NDVI）, photochemical reflectance index （PRI） and water index （WI）） and solar-induced fluorescence at 761 nm （F761）, as well as plant leaf water content （LWC） and leaf area index （LAI）. [Result] The results indicated that LWC, LAI, CAP, NDVI, PRI and F761showed a downward trend along with the prolonging of the drought stress, while WI showed an in- creasing trend. Extremely significant differences （P〈 0.01） were found among drought treatments and CK for all parameters. NDVI, PRI and WI were significantly correlated with LAI and LWC （P〈 0.01）. The absolute values of correlation coefficient for NDVI, PRI, WI, F761with LAI （Irl〉0.6） were lower than those with LWC （Irl〉0.8）. F761 was better correlated with leaf water content and LAI than other spectral indices. [Conclusion] It was concluded that CAP, PRI, NDVI, WI and F761 are good indi- cators in cotton leaves during drought stress. Solar-induced fluorescence seems more sensitive to leaf water status than other spectral indices at canopy level in cotton.