菊芋(Helianthus tuberoses)蒸腾特性与水分利用效率对光辐射和CO_2浓度变化的响应

Response of Transpiration Characteristics and Water Use Efficiency of Helianthus tuberoses to the Enhancement of Simulated Photosynthetic Radiation and CO_2 Enrichment

利用便携式光合气体分析系统(LI-6400)在控制光照强度和CO2浓度的条件下,测量和分析了菊芋(Heli-anthustuberoses)的光合速率(Pn)、蒸腾速率(Tr)、胞间CO2浓度(Ci)、气孔导度(Gs)和饱和水汽压亏缺(Vpdl)对不同光辐射(SPR)强度与CO2浓度的响应。结果表明,Pn、Tr、Gs、WUE均随SPR的升高而增大,增幅趋缓,最终趋于动态平衡。Ci与Vpdl则随SPR的增强而减小,SPR高于600μmol.m-2.s-1之后,Ci达到平衡状态。CO2浓度从0增至800μmol.mol-1的过程中,菊芋Pn逐渐增大,从800增至2000μmol.mol-1过程中,其Pn逐渐降低。Ci、Vpdl和WUE随着CO2浓度的升高而增大,Gs和Tr则随CO2浓度的升高而减小。菊芋叶片的光饱和点(LSP)约在1400μmolCO2m-2.s-1,光补偿点(LCP)约19μmolCO2m-2.s-1。

To determine how transpiration characteristics and water use efficiency of Helianthus tuberoses respond to simulated photosynthetic radiation enhancement and CO_2 enrichment,the authors used LI-6400 Portable Photosynthesis System to examine photosynthetic rate（Pn）,transpiration rate（Tr）,intercellular CO_2 concentration（Ci）,stomatal conductance（Gs）and vapor pressure deficit based on leaf temp（Vpdl）of Helianthus tuberoses under simulated photosynthetic radiation（SPR）intensities and CO_2 concentration.Pn,Tr,Gs and WUE（water use efficiency）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.Whereas,Ci and Vpdl decreased with SPR intensity increase,and Ci reached dynamic balance as SPR intensity exceeded 600 mol·m-2·s-1.Pn increased with CO_2 concentration between 0 and 800 μmol·mol-1,and then decreased as CO_2 concentration increased from 800 to 2 000 μmol·mol-1.Ci,Vpdl and WUE of Helianthus tuberoses increase with the increase of CO_2 concentration,on the contrary,Gs and Tr decreased.The Light Saturation Point（LSP）measured in leaves was at 1 400 mol CO_2·m-2·s-1,and the Light Compensation Point（LCP）was at 19 mol CO_2·m-2·s-1.