2023年5月29日 星期一
干旱胁迫对美国流苏树幼苗光合特性和叶片结构的影响
Effect of drought stress on photosynthetic characteristics and leaf structure of Chionanthus virginicus seedlings
2023年 第32卷 第3期 页码[61-70]    下载全文[11.4MB]  
摘要

以美国流苏树(Chionanthus virginicus Linn.)2年生幼苗为实验材料,设置对照(土壤相对含水量为75%~80%)、轻度干旱胁迫(土壤相对含水量为55%~60%)、中度干旱胁迫(土壤相对含水量为40%~45%)和重度干旱胁迫(土壤相对含水量为25%~30%)4个处理水平,对不同干旱胁迫条件下美国流苏树叶片光合特性和结构的变化进行了比较和分析。结果显示:随胁迫时间延长,各处理组美国流苏树叶片的叶绿素a、叶绿素b和总叶绿素含量呈波动降低的趋势。在胁迫14~42 d,美国流苏树叶片的叶绿素a、叶绿素b和总叶绿素含量在各处理组间均无显著差异;在胁迫70 d,中度和重度干旱胁迫处理组的上述3个指标均显著低于对照组。总体上看,随胁迫程度增加,同一时间美国流苏树叶片净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)呈降低的趋势;水分利用效率(WUE)呈波动降低的趋势;胁迫14、28和56 d的叶片胞间CO2浓度(Ci)呈降低的趋势,胁迫42和70 d的叶片Ci值呈波动升高的趋势,重度干旱胁迫70 d的叶片Ci值最大。各干旱胁迫处理组叶片最大荧光(Fm)和可变荧光(Fv)低于对照组,但均无显著差异;初始荧光(Fo)高于对照组,PSⅡ最大光化学效率(Fv/Fm)和PSⅡ潜在活性(Fv/Fo)低于对照组,但仅重度干旱胁迫处理组与对照组有显著差异。干旱胁迫处理后,美国流苏树叶片总厚度、栅栏组织厚度、海绵组织厚度和组织结构疏松度均增加,叶片组织结构紧密度和栅海比减小;中度和重度干旱胁迫下细胞中叶绿体和淀粉粒降解,嗜锇颗粒增多,质壁产生分离,细胞结构破坏严重。综上所述,美国流苏树在干旱胁迫下可以通过降低光合作用、改变叶片结构特征来提高抗旱能力,且在轻度干旱时具有较强的适应能力。

Abstract

Taking two-year-old Chionanthus virginicus Linn. seedlings as experimental materials, four treatments namely the control (soil relative water content of 75%-80%), mild drought stress (soil relative water content of 55%-60%), moderate drought stress (soil relative water content of 40%-45%), and severe drought stress (soil relative water content of 25%-30%) were set, and the changes of photosynthetic characteristics and structure of leaves of C. virginicus under different drought stress conditions were compared and analyzed. The results show that with the elongation of stress time, contents of chlorophyll a, chlorophyll b, and total chlorophyll in leaves of C. virginicus in each treatment group show a fluctuation decrease tendency. During 14-42 d of stress, there are no significant differences in contents of chlorophyll a, chlorophyll b, and total chlorophyll in leaves of C. virginicus among each treatment group; at 70 d of stress, these three abovementioned indexes in moderate and severe drought stress treatment groups are all significantly lower than those in the control group. Overall, with the increase of stress degree, net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) of leaves of C. virginicus at the same time show a tendency to decrease; water use efficiency (WUE) shows a fluctuation decrease tendency; intercelluar CO2 concentration (Ci) of leaves at 14, 28, and 56 d of stress show a tendency to decrease, those of leaves at 42 and 70 d of stress show a fluctuation increase tendency, and that of leaves at 70 d of severe drought stress is the largest. Maximum fluorescence (Fm) and variable fluorescence (Fv) of leaves in each drought stress treatment group are lower than those in the control group, but there are no significant differences; initial fluorescence (Fo) is higher  than that in the control group, maximum photochemical efficiency of PSⅡ (Fv/Fm) and potential activity of PSⅡ (Fv/Fo) are lower than those in the control group, but only the severe drought stress treatment group is significantly different from the control group. After drought stress treatment, total leaf thickness, palisade tissue thickness, spongy tissue thickness, and tissue structure looseness of C. virginicus all increase, while leaf tissue structure tightness and ratio of palisade tissue to spongy tissue decrease; the chloroplast and starch grain degrade, the osmophilic gramule increases, and plasmolysis appears in cells, and the cell structure is severely damaged under moderate and severe drought stresses. Taken together, C. virginicus can improve droughtresistant ability under drought stress via reducing photosynthesis and changing leaf structure characteristics, and it possesses strong adaptability under mild drought stress.

关键词干旱胁迫; 美国流苏树; 光合特性; 解剖结构; 超微结构
Key wordsdrought stress; Chionanthus virginicus Linn.; photosynthetic characteristics; anatomical structure; ultra-microstructure
作者韩睿婷, 韩丽霞, 张鸽香
所在单位南京林业大学风景园林学院, 江苏 南京 210037
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下载次数20
基金项目国家林业局“948”项目(2014-4-17); 江苏高校品牌专业建设工程项目(PPZY2015A063)