干旱胁迫下春玉米叶片光合生理对不同叶温的响应——以大喇叭口期为例
Response of spring maize leaf photosynthetic physiology to different leaf temperatures under drought stress:A case study of spring maize at the flared stage
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摘要: 以桶栽土培春玉米为研究对象,设置不同叶温梯度,利用 Li-6400 便携式光合作用系统测定受旱过程中春玉米叶片在不同叶温下的光合生理变化及光响应过程,揭示干旱区春玉米受旱过程中叶片光合生理对叶温变化的响应机制。结果表明:受旱过程中,春玉米叶片净光合速率、蒸腾速率、气孔导度和气孔限制随光合有效辐射增强而增大;其中叶片净光合速率、蒸腾速率和气孔导度呈现干旱初期＞中期＞末期(P<0.05),而气孔限制值呈现干旱初期＜中期＜末期。光响应过程中,干旱初期叶片净光合速率、蒸腾速率、气孔导度随叶温升高而增大,但极端高温40 ℃时叶片净光合速率和气孔导度反而减小;随着干旱发展,在干旱中期和末期叶片净光合速率峰值曲线对应的适宜温度逐步下降,分别为31 ℃和25 ℃;气孔导度的适宜温度为25 ℃;蒸腾速率与叶片净光合速率、气孔导度不同,适宜温度较高;气孔限制在不同叶温下差异不显著,呈现干旱影响大于高温。对叶温的响应,叶片净光合速率、气孔导度和气孔限制呈抛物线型,随叶温升高先增大后减小。干旱末期高温对叶片光合生理有显著的限制作用。随着干旱发展,高温增加了玉米受旱强度,解除高温干旱的最佳时机在干旱中期。Abstract: Taking spring maize as the research object,bucket planting experiment was conducted to determine the photosynthetic physiological changes and light response processes of spring maize leaves under different leaf temperature gradients during drought by using Li-6400 portable photosynthesis system,and to reveal the response mechanism of leaf photosynthetic physiology to leaf temperature changes during spring maize drought in arid areas.The results showed as follows:During drought,the net photosynthetic rate (Pn),transpiration rate (Tr),stomatal conductance (Gs) and stomatal limit value (Ls) of spring maize increase with the increase of photosynthetic effective radiation (PAR).Pn,Tr and Gs show the initial>middle>end of drought (P<0.05),while Ls show the initial
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