高CO2浓度和干旱胁迫对4种树苗光合特性的影响  

Influences of Drought Stress on Photosynthetic Characteristics and Water Use Efficiency of 4 Tree Species under Elevated CO_2 Concentration

作　　者：刘娟娟[1] 李吉跃[2] 张建国[1] 

机构地区：[1]中国林业科学研究院林业研究所,林木遗传育种国家重点实验室,国家林业局林木培育重点实验室,北京100091 [2]华南农业大学林学院,广东广州510642

出　　处：《林业科学研究》2015年第3期339-345,共7页Forest Research

基　　金：国家自然科学基金项目(30471370);教育部博士点基金资助项目(20050022003)

摘　　要：在不同CO2浓度(380、720μmol·mol-1)的密闭式生长箱内,对5年生油松和侧柏苗、3年生元宝枫和刺槐苗进行培养,研究CO2浓度升高与干旱胁迫对4种树苗光合特性和水分利用效率的影响。结果表明:高CO2浓度均能增加正常水分和重度干旱胁迫下4个树苗的光合速率(Pn)、胞间CO2浓度(Ci)和瞬时水分利用效率(WUEi),而降低蒸腾速率(Tr)和气孔导度(Cond);在轻度干旱和重度干旱条件下,Pn、Ci、Tr、Cond和WUEi增加,刺槐的WUEi却减少。CO2浓度增加,4个树种在同一干旱时期的碳稳定同位素比值(δ13C)减少。随着干旱胁迫加剧,不同CO2浓度下4个树种的Pn、Tr和Cond减少,而720μmol·mol-1CO2浓度下4个树种和380μmol·mol-1CO2浓度下刺槐和元宝枫的WUEi和δ13C增加,而380μmol·mol-1CO2浓度下油松和侧柏的WUEi和δ13C先增加,到重度干旱时又下降。CO2浓度增加与干旱胁迫的交互作用减弱了干旱胁迫或者CO2浓度增加中的某一因子对气孔变化的敏感性,使得气孔变化缓慢,延迟了水分胁迫的发生。Five-year-old Pinus tabulaeformis and Platycladus orientalis and three-year-old Acer truncatum and Robin- ia pseudoacacia saplings were exposed to 720 μmol mol-1 CO2 for 13 months. The leaf photosynthetic ratio （Pn）, internal CO2 concentration （Ci）, transpiration ratio （Tr） and stomatal conductance （Cond） were measured by Li- 6400. The leaf Carbon isotope ratio （δ13C） was measured by Isotope Ratio Mass Spectrometer. Under normal water and heavy drought conditions, the Pn, Ci and WUEi of the 4 tree species increased, while the Tr and Cond reduced along with the CO2concentration. Under mild drought and moderate drought conditions, the Pn, Ci, Tr, Cond and WUEi increased along with COzconcentration. The WUEi of R. pseudoacacia under 720 μmol mol-1 CO2concentration reduced along with CO, concentration under mild drought, moderate drought and heavy drought conditions. In the same drought condition, the leaf δ13C values increased along with CO2concentration. The Pn, Tr and Cond reduced along with drought condition. The leaf WUEi and δ13C values of the 4 tree species increased under 720 μmol mol-1 CO2 concentration, while A. truncatum and R. pseudoacacia under 380 μmol mol- 1 CO2 concentration in- creased under mild drought and moderate drought conditions and then reduced under heavy drought condition. The interaction of elevated CO2 concentration and drought stress decreased the sensitivity of stomata, which changed quickly under elevated CO2concentration or drought stress, and postponed the occurrence of drought stress.

关 键 词：CO2浓度增加 干旱胁迫 光合特性 水分利用效率 碳稳定同位素 

分 类 号：S718.43[农业科学—林学]