以茶树品种龙井43为试验材料,研究外源24-表油菜素内酯(EBR)处理对高温胁迫下茶树叶片光合特性、叶绿素荧光参数、丙二醛(MDA)含量和抗氧化酶活性的影响.研究发现:叶面喷施EBR能显著提高高温胁迫下茶树叶片的净光合速率(Pn),气孔导度(Gs),Rubisco最大羧化速率(Vc,max)、Rubisco的最大再生速率(Jmax)和PSⅡ最大光化学效率(Fv/Fm);同时外源EBR处理后,高温胁迫下茶树叶片中的抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性显著提高,而MDA含量则显著下降.外源EBR主要通过解除非气孔因素的限制、促进光合碳反应的进行来缓解高温胁迫对茶树叶片光合作用的抑制;同时EBR能够有效利用多种抗氧化途径以清除其细胞内的自由基和活性氧,最终缓解高温胁迫对茶树的伤害.%The present study investigated the effects of exogenous 24-epibrassinolide ( EBR) on gas exchange, chlo-rophyll fluorescence parameters, lipid peroxidation ( MDA content) and antioxidant enzymes activities in tea ( Camel-lia sinensis cv. Longjing 43) leaves under heat stress. Results showed that foliar application of EBR could signifi-cantly increase Pn, Gs, Vc ,max , Jmax and Fv/Fm in tea leaves under heat stress. Moreover, EBR remarkably in-creased activities of APX, CAT, SOD and POD, but decreased MDA content in tea leaves following heat stress. These results suggest that exogenous EBR mitigates heat stress-induced photosynthetic inhibitions in tea leaves, mainly by eliminating the non-stomatal limitations and promoting the photosynthetic carbon reaction. Furthermore, EBR strengthened the antioxidant system effectively to scavenge harmful levels of reactive oxygen species and thus al-leviated heat stress in tea plant.
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