4种披碱草属植物光合作用光响应特性的比较

A comparison of photosynthesis responses to light of four Elymus species

利用人工模拟光源研究了4种披碱草属植物的光合速率(Pn)、蒸腾速率(Tr)、水分利用效率(WUE)、气孔导度(Gs)、胞间CO2(Ci)浓度及叶面饱和水压亏(Vpdl)随模拟光辐射(SPR)增强的变化规律及其相关性,并计算了各材料表观量子效率及其光饱和点与光补偿点等。结果表明,4种植物的Pn和Tr均随SPR的增强而增大,在相同的光照强度下,麦宾草的光合速率较高,披碱草次之,其他2种材料净光合速率近乎一致。麦宾草和肥披碱草的Tr明显高于老芒麦和披碱草;披碱草属不同材料的WUE随SPR的加强而呈递增规律,其中WUE的大小顺序为老芒麦>披碱草>麦宾草>肥披碱草;4种植物气孔导度均随模拟光辐射强度的升高而增大,麦宾草和披碱草的Gs明显高于其他2种植物;4种植物胞间CO2均随着SPR的增强和Pn的增大而减少。当SPR从0增至500μmol/(m2·s)时,4种植物Vpdl有一个小的下降过程,之后除披碱草缓慢下降外,其他材料随SPR增加而缓慢增加,麦宾草和肥披碱草的Vpdl明显高于其他2种材料。老芒麦和麦宾草光补偿点相对较低,说明两者利用弱光的能力相对较强,麦宾草和披碱草光饱和点较高,说明两者利用强光的能力较强。通过综合分析,利用光能的能力高低顺序为:麦宾草>披碱草>老芒麦>肥披碱草,也就是无论在强光或弱光条件下,麦宾草和披碱草利用光能的能力较强。

The net photosynthetic rate （Pn）, transpiration rate （Tr）, water use efficiency （WUE）, stomatal conductance （Gn）, intercellular CO2 concentration （Ci） and vapor pressure deficit （Vpdl） of four Elyrnus species were determined under simulated photosynthetic radiation （SPR） and the apparent quantum yield （AQY）, light saturation point （LSP） and light compensation point （LCP） were calculated. The P, and Tr increased with an increase in SPR in all four species. Under the same light intensity, E. tangutorum had the highest Pn of the four species, while E. dahuricus was medium, and the other two species had almost the same Pn. The Tr of E. tangutorurn and E. excelsus were significantly higher than those of E. sibiricus and E. dahuricus. The WUE also increased with an increase in SPR, and the order of WUE for the species was E. sibiricus E. dahuricus〉E, tangutorum〉E, excelsus. The G, increased with an increased SPR. The Gs of E. tangutorum and E. dahuricus were significantly higher than those of the other two species. The Ci decreased with increases in SPR and Pn. The Vpdl first dropped with an SPR increase from 0 to 500μmol/（m^2·s）, and except for E. dahuricus, the other two species then showed an increase in the Vpdl with an SPR increase. Overall, the Vpdl of E. tangutorum and E. excelsus were significantly higher than those of the other two species. In addition, E. sibiricus and E. tangutorurn had lower LCPs than the other species, indicating their higher ability to use light under low-light conditions. Both E. tangutorurn and E. dahuricus had a high LSP among, showing their better ability to use strong light. In conclusion, E. tangutorum and E. dahuricus had a relatively higher capacity for light utilization than E. sibiricus and E. excelsus; that is, they had higher photosynthetic efficiency whether under high or low-light conditions.