干旱及复水对小冠花光合及叶绿素荧光参数的影响

Effects of Drought and Rewatering on the Photosynthesis and Chlorophyll Fluorescence of Coronilla varia

为研究持续控水干旱胁迫和复水对小冠花（Coronilla varia）光合和叶绿素荧光参数的影响,从光合生理角度揭示小冠花对干旱的适应性,采用盆栽控水法对小冠花持续干旱18 d后复水,以保持土壤相对含水量在70％～75％的小冠花为对照,在干旱6,12和18 d及复水后3d测定小冠花光合及叶绿素荧光参数.结果表明：在停止浇水后第6,12和18 d时,土壤相对含水量（RWC）从75％分别下降到了50％,35％和25％.小冠花在受到土壤干旱胁迫后,净光合速率（Pn）、气孔导度（Gs）、胞间二氧化碳浓度（Ci）、蒸腾速率（Tr）、PSⅡ最大光化学量子效率（Fv/Fm）、PSⅡ光能实际转化效率（Yield）、PSⅡ非循环电子传递速率（ETR）、光化学荧光猝灭系数（qP）均呈下降趋势,而叶片初始荧光（F0）、非光化学荧光淬灭系数（NPQ）呈上升趋势.胁迫第6d时,Gs和Tr下降,其余各指标均无显著变化;第12和18 d时,Pn,Gs,Ci,Tr,Fv/Fm,Yield,ETR和qP均显著下降（P＜0.05）,NPQ显著升高（P＜0.05）;而Fv在持续干旱第18 d时显著高于对照（P＜0.05）.同时,绝大多数参数的变化幅度随胁迫时间增加而增大;但在复水3d后,处理和对照的各参数均无显著差异.这表明持续的干旱胁迫影响小冠花光合作用,重度胁迫还会造成光合中心结构受损,此作用和干旱胁迫的时间长短相关;但小冠花对干旱有较强的适应性,在胁迫解除后,受损的光合中心能及时得到修复,光合作用能很快恢复至正常水平.

In order to disclose the photosynthetic adaptability of Coronilla varia to drought, the effect of continuous drought stress and rewatering on the characteristics of photosynthesis and chlorophyll fluores- cence were studied. C. varia was not watered for 18 days, and then rewatered during pot test. The plants growing in the soil with 70%-75% relative water content （RWC） were taken as control. The parameters of photosynthesis and chlorophyll fluorescence were measured on the 6th, 12th, 18th day after no-watering and the 3＇d day after rewatering. Results showed that the RWC of soil decreased from 75 % to 50 %, 35 and 25% on the 6th , 12th and 18＇h day after the plants were not watered, respectively. The Pn, Gs, Ci, Tr, Fv/Fm, Yield, ETR and qP of leaf significantly decreased on the 12＇h and 18th day after no-watering, while NPQ significantly increased （P〈0. 05）. However, Fo didn＇t significantly increased during drought stress. The most parameters of photosynthesis and chlorophyll fluorescence increased with the stress time going. However, there was no significant difference for all parameters between treatments and control on the 3rd day after rewatering. These results indicated that continuous drought stress influenced the photo- synthesis of C. varia, and the severe stress could lead to the damage of photosynthetic reaction center. However, the damage could be repaired soon and the photosynthesis could quickly be back to the level of control after rewatering due to the good adaptability of C. varia to drought stress.