【摘要】 以2年生沙蒿实生苗为材料，通过盆栽控水试验测定不同水分条件沙蒿叶片水分含量、光合特性及抗氧化酶活性，分析各指标在干旱胁迫过程中的变化特征、响应机制及其与土壤水分的定量关系，揭示沙蒿对干旱胁迫的响应规律。结果表明，1)随着干旱胁迫时间增加，沙蒿叶片相对含水量(RWC)持续降低，叶片水分亏缺(RWD)呈波动式上升趋势；2)沙蒿总叶绿素(Chl)、叶绿素a(Chla)和叶绿素b(Chlb)含量均随胁迫时间增加而持续降低，胁迫30 d时均降为最小值，而类胡萝卜素含量随胁迫时间增加逐渐升高；3)沙蒿净光合速率(P_n)、蒸腾速率(T_r)、水分利用效率(WUE)等主要气体交换参数对土壤水分都表现出明显的阈值响应，适宜进行正常光合生理活动的土壤含水率阈值为6.48%～17.51%;4)沙蒿PSⅡ最大光化学效率(F_v/F_m)、有效光化学量子效率(F_v′/F_m′)及光化学淬灭系数(qP)均随干旱胁迫时间增加而逐渐降低，而非光化学淬灭系数(NPQ)呈平缓上升趋势；5)沙蒿叶片中丙二醛(MDA)含量随胁迫时间增加而升高，持续干旱胁迫导致MDA大量积累；超氧化物歧化酶(SOD)活性也随胁迫时间增加而升高，30 d时达到最大值；过氧化物酶(POD)活性能对干旱胁迫做出较早的响应，胁迫12 d时达到峰值；过氧化氢酶(CAT)活性对干旱胁迫的敏感性较差，持续干旱对沙蒿CAT活性产生抑制。研究发现，在干旱胁迫条件下，沙蒿会通过提高叶片光能捕获转换能力、增强抗氧化水平等方式适应干旱环境。更多还原

【Abstract】 Two-year-old Artemisia desertorum seedlings were used as materials to determine the water, photosynthetic characteristics and antioxidant enzyme activity characteristics of the leaves under different water conditions by potted plan water control experiment.The variation characteristics, response mechanism and quantitative relationship with soil moisture of each index during drought stress were analyzed, so as to reveal the response law of A.desertorum to drought stress.The results showed that 1) relative water content(RWC) of A.desertorum leaves continued to decrease with the increase of drought stress days, relative water deficit(RWD) showed a fluctuating upward trend.2) The contents of total chlorophyll(Chl),Chla and Chlb all decreased with the increase of stress days, and decreased to the minimum at 30 days, while the content of carotenoid increased gradually with stress days.3) The main gas exchange parameters such as net photosynthetic rate(P_n),transpiration rate(T_r) and water use efficiency(WUE) showed obvious threshold response to soil moisture, and the threshold value of soil moisture was 6.48%-17.51%,which was suitable for normal photosynthetic physiological activities.4) F_v/F_m、F_v′/F_m′ and qP decreased with stress days and light intensity, while NPQ increased slowly.5) The content of MDA increased with stress days, and the content of SOD increased with stress days, and the maximum was at 30 d.POD could respond to drought stress early, the CAT activity was inhibited by persistent drought stress, and the sensitivity of CAT to drought stress was poor.At the late stage of stress, under drought stress conditions, A.desertorum can adapt to arid environments by improving the light energy capture and conversion ability of leaves and enhancing the antioxidant capacity.更多还原