Responses of antioxidant defense system of Lespedeza davurica to enhanced UV-B radiation | 达乌里胡枝子抗氧化防御系统对增强UV-B辐射的动态响应

chinois. 为探究增强UV-B辐射对达乌里胡枝子（Lespedeza davrica）抗氧化能力的影响，采用盆栽试验研究其在不同UV-B辐射强度（CK=0, T1=1.944kJ/m2/d, T2=3.002kJ/m2/d）下的抗氧化保护系统相关指标的动态响应，UV-B辐射处理持续15d，每3d取样一次至结束后第3d再取样一次。结果表明：随着处理时间的延长，增强UV-B辐射使超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性降低，抗坏血酸过氧化物酶（APX）和过氧化物酶（POD）活性升高，且SOD，POD和CAT的活性随着辐射强度的增加而降低，APX活性在开始处理9d内随着辐射强度的增加而增加，此后随着辐射强度的增加而降低；增强UV-B辐射使抗坏血酸（AsA）含量增加，类胡萝卜素（Car）含量降低，且二者的含量均随着辐射强度的增加而降低；增强UV-B辐射使超氧阴离子（O2.-）、丙二醛（MDA）含量升高，O2.-含量和MDA含量均随着辐射强度的增加而增加。UV-B处理结束后，除SOD活性、POD活性、AsA含量呈下降趋势外，其他指标都呈上升趋势。通过隶属函数法综合评价得出：增强UV-B辐射降低了达乌里胡枝子的抗氧化能力，随着UV-B辐射强度的增加，抗氧化能力降低。

anglais. The objective of this study was to investigate the effects of different UV-B radiation intensity (CK, T1, T2) on antioxidant defense system and other related indicators of Lespedeza davurica (Laxm.) Schindl. Malonaldehyde (MDA), ascorbic acid (AsA) and carotenoid (Car) contents, as well as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activities of leaves from Lespedeza davurica under different UV-B radiation intensity were investigated. Samples were collected once every three days. The UV-B treatment was continued 15 days. Result indicated that SOD and POD activities decreased, APX and POD activities increased with UV-B radiation enhanced during the whole treatment time. SOD, POD and CAT activities decreased with UV-B radiation intensity increasing. APX activity increased during the first 9-day treatment with radiation intensity increasing then decreased with radiation intensity increasing. UV-B radiation increased AsA content, decreased Car content. Both AsA and Car contents decreased with radiation intensity increasing when compared with control.O・-2and MDA increased with radiation intensity increasing. All other tested indicators increased except SOD and POD activity as well as AsA content decreased after UV-B radiation treatment. Comprehensive evaluation of subordinate function showed that UV-B radiation reduced the antioxidant capacity of Lespedeza davurica, and the antioxidant capacity decreased with UV-B radiation intensity increasing.