摘要
在人工控制光照强度和CO_2浓度条件下,测量了禾本科C_4植物狗尾草(Setaria viridis)的光合速率(Pn),蒸腾速率(Tr),胞间CO_2浓度(Ci),气孔导度(Gs)和叶面饱和水汽压亏缺(Vpdl)对不同模拟光辐射(SPR)强度与CO_2浓度的响应。结果表明:Pn,Tr及Gs均随SPR的升高而增大,增幅趋缓,最终趋于动态平衡。SPR增强的起始阶段,水分利用率(WUE)逐渐增大,在SPR为1200μmol·m^(-2)·s^(-1)时达最大值,然后逐渐降低。Ci与Vpdl则随SPR的增强而减小,SPR高于600 μmol·m^(-2)·s^(-1)之后,两者均达到平衡状态。CO_2浓度从300增至600μmol·mol^(-1)的过程中,狗尾草Pn逐渐增大,从600增至1000 μmol·mol^(-1)过程中,其Pn逐渐降低。Ci、Vpdl和WUE随C0_2浓度的升高而增大,Gs和Tr则随CO_2浓度的升高而减小。即禾本科一年生C_4植物的光合作用对CO_2浓度升高响应不敏感,水分蒸腾消耗的减少和WUE的提高对CO_2浓度升高的响应极显著。可见,CO_2浓度升高对C_4植物光合作用的直接促进作用有限,但是却能从提高现有水分利用效率途径促进植物的第一性生产。
To determine how transpiration characteristics and water use efficiency of annual €4 plants respond to simulated photosynthetic radiation enhancement and CO2 enrichment, we used LT-6400 Portable Photosynthesis System to examine photosynthesis rate ( Pn ) , transpiration rate ( Tr ) , intercellular CO2 concentration ( Ci) , stomatal conductance ( Gs ) and vapor deficit at the leaf surface ( Vpdl) of Setaria viridis under simulated photosynthetic radiation (SPR) intensities from 0 to 2 400 jumol · m -2 · s-1 and CO2 concentration from 300 to 1 000 μmol · mol -1. Pn, Tr and Gs increased with enhanced SPR intensity. The increase in Pn, Tr and Gs with each unit SPR added was reduced as SPR intensity increased. At last, these physiological parameters tend to dynamic balance. Water use efficiency ( WUE) increased with enhanced SPR, then plateaued as SPR intensity exceeded 1 200 μmol·m-2 ·s-1 . For photosynthesis process demands C02, so Ci intensity enhancement. Vpdl also decreased with SPR intensity increase, then reached dynamic balance as SPR intensity exceeded 600 μmol · m- 2 · s-1. Pn increased with CO2 concentration between 300 and 600μmol · mol -1, and then decreased as C02 concentration increased from 600 to 1 000 μmol· mol-1. Ci, Vpdl and WUE of Setaria viridis rose with the elevation of CO2 concentration. Both Gs and Tr dropped as the CO2 concentration was elevated . We conclude that Pn of annual C4 plants was not sensitive to C02 concentration variation. The response of Tr and WUE to CO2 enrichment was most significant. It is obvious that the function of instantaneous simulated CO2 enrichment to increased photosynthesis rate was gradually diminished. However, it could enhance primary production by improving the use efficiency of existing water.
出处
《植物生态学报》
CAS
CSCD
北大核心
2003年第4期448-453,共6页
Chinese Journal of Plant Ecology
基金
国家重点基础研究发展规划项目(G1999043407)
国家自然科学基金(30070545)
关键词
狗尾草
蒸腾特性
水分利用
光辐射
CO2浓度
Transpiration characteristics, Water use efficiency, Simulated photosynthetic radiation, CO2 con-centrations, Setaria viridis
