春、夏季土壤水分对连翘光合作用的影响  

Effects of soil water on photosynthesis of Forsythia suspensa( Thunb. ) Vahl. in spring and summer

作　　者：郎莹[1] 汪明[1] 

机构地区：[1]北京师范大学减灾与应急管理研究院,地表过程与资源生态国家重点实验室,北京100875

出　　处：《生态学报》2015年第9期3043-3051,共9页Acta Ecologica Sinica

基　　金：973计划项目(2012CB955404);国际科技合作项目(2012DFG20710)

摘　　要：在全球气候和环境变化的背景下,我国华北地区表现出平均气温升高和降水时空格局变化的趋势,导致华北地区春、夏季土壤水分变化加剧,从而一定程度上制约了植物的光合作用和生物生产力。为探索植物光合作用对土壤水分变化以及所处生长发育季节的响应特点,以华北地区为研究区,利用Li-6400光合作用测定系统,通过受控温室内盆栽控水的方法,测定和分析了春、夏两个季节2年生连翘叶片在多级连续土壤水分梯度下的光合作用光响应过程。研究结果表明:1)弱光(光合有效辐射PAR≤200μmol m-2s-1)下,净光合速率(Pn)、气孔导度(Gs)、水分利用效率(WUE)光响应过程对季节不敏感,强光下Pn-PAR、Gs-PAR过程与土壤水分和季节同时有关,春、夏两个季节Pn、Gs对强光响应的差异更多表现在阈值:土壤相对含水量(SRWC)>40%范围。2)春、夏两个季节表观量子效率(φ)、Pn、WUE、Gs、胞间CO2浓度(Ci)、气孔限制值(Ls)对SRWC具有相似的响应过程,但两个季节各个参数达到阈值时的SRWC不同,说明水分阈值是不同季节植物光合作用响应土壤水分产生差异的关键。3)春、夏两个季节连翘光合作用较适宜的土壤水分分别是春季51.84%≤SRWC≤58.96%,夏季52%≤SRWC≤83.34%;此SRWC范围内,春、夏两个季节连翘光合作用适宜的PAR范围相似,为1000μmol m-2s-1≤PAR≤1400μmol m-2s-1。因此,为适应未来气候和环境变化,有必要根据植物所处的物候期确定环境因子(土壤水分、光照、温度等)的适宜范围和关键阈值,更好地为区域适应性措施的探索提供科学依据。In face of global climate and environment change,the North China is experiencing the increasing trend of mean temperature and the pattern change of precipitation,resulting in more and more severe volatility in regional soil water contents. This phenomenon may significantly affect the photosynthesis,growth and productivity of plants in the region. The objective of this study is to explore the photosynthetic and physiological characteristics of Forsythia suspensa（ Thunb.）Vahl. under different soil water conditions and various light intensities in both spring and summer. With the quantified relationship between the photosynthesis and soil water content in both seasons, this study can help understand the responsive and adaptive characteristics of Forsythia suspensa for more severe and longer droughts that may occur as a result of regional climate change in the North China. By using a Li-6400 portable photosynthetic system,the light response processes of the two-year Forsythia suspensa under multiple controlled soil water content treatments in both spring and summer were measured and analyzed. The response of photosynthetic parameters under both low light and saturated lightconditions in spring and summer were also investigated. The results show that the photosynthetic characteristics of Forsythia suspensa are related to the photosynthetically active radiation（ PAR）,the relative soil water content（ SRWC） and the periods of plant growth and development. First,when PAR≤200 μmol m-2s-1,the light responses of net photosynthetic rate（ Pn）,stomatal conductance（ Gs）,and water use efficiency（ WUE） were not sensitive to seasons,while the responses of Pn and Gs were related to both soil water contents and seasons in strong light,and their differences between spring and summer appeared to be significant when the SRWC40%. When the SRWC≤32. 41% in spring and SRWC≤38. 65% in summer,Pn and Gs maintained lower level when PAR increased from 0 to 1800 μmol m-2s-1. Second,when37. 52% ≤ SRWC ≤ 42. 55%

关 键 词：土壤水分 光合作用 光响应 连翘 气候变化 

分 类 号：S685.24[农业科学—观赏园艺]