三裂叶蟛蜞菊光合生理特性对光合有效辐射增强的响应

Response of photosynthetic physiological characteristics of Wedelia trlobata to the increasing photosynthetic active radiation

三裂叶蟛蜞菊是华南地区重要的园林绿化植物。在人工控制光合有效辐射(PAR)条件下,测量了三裂叶蟛蜞菊在深秋和冬季的净光合速率(Pn),蒸腾速率(Tr),胞间CO2浓度(Ci)和气孔导度(Gs)等光合生理特性对连续光照强度增强的响应。结果表明:Tr、Pn均随PAR的增强而增大,且增幅稳定;Gs在PAR增强的起始阶段先下降,从200μmol/(m2·s)后,逐渐上升,尤其11 月较明显;Ci随着PAR的增强而逐渐减少,在PAR为2 000μmol/(m2·s)后趋于平衡。温度对三裂叶蟛蜞菊光合生理特性的影响较显著,但若光照充分,其光合速率也能提高。三裂叶蟛蜞菊有较高的水分利用率,表明它比较耐干旱。

The effect of photosynthetic active radiation (PAR) on the photosynthetic physiological characteristics of Wedelia trlobata ,including photosynthesis rate (Pn), transpiration rate (Tr), intercellular CO_2 concentration (Ci) and stomatal conductance (Gs), were studied under the controlled PAR condition (from 0 mol/m^2 s to 2600 mol/m^2 s). The results indicated that: Tr and Pn increased with the enhanced PAR intensity. Gs decreased with the enhanced of PAR at the beginning, but increased as PAR increased later. Ci decreased with the increasing of PAR, then reach balance when PAR intensity was more than 2000 mol/m^2 s. The values of Tr and Pn in November were higher than in January, but the value of Ci was lower. It was obvious that the influence of the temperature change on photosynthetic physiological character of Wedelia trlobata was significant.