光叶子花光合特性研究

Study on Photosynthetic Characteristics of Bougainvillea glabra

利用LI-6400便携式光合作用测定系统研究了光叶子花叶片气孔导度(Gs)、净光合速率(Pn)、蒸腾速率(Tr)和水分利用效率(WUE)对光照强度(PFD)增强和CO2浓度升高的响应及其日变化,结果表明,在不同光照强度下,光叶子花叶片Gs、Pn和WUE随PFD的增强而增大,当达到最大值后又随PFD的增强而逐渐减小,且分别在PFD为2 000、1 500、300μmol.m-2.s-1时达到各自的最大值,而Tr随PFD的增强一直呈增大趋势;在不同CO2浓度下,光叶子花叶片Gs和Tr均随CO2浓度升高而逐渐降低,相反Pn和WUE却随CO2浓度的升高而呈明显的增加趋势;光叶子花叶片Gs、Pn和Tr的日变化均随时间的增加而增大,并在13:00时达到最大值,之后又随时间的增加而逐渐减小,且Gs、Pn和Tr的日变化均呈单峰型,而WUE随时间的增加未表现出明显的日变化规律。

Study on responses and their diurnal variation of stomatal conductance （Gs）, net photosynthesis rate （Pn）, transpiration rate （Tr） and water use efficiency （WUE） of Bougainvillea glabra leaves on enhanced photosynthetic photon flux density （PFD） and increased CO2 concentration was carded out by LI-6 400 Portable Photosynthesis System. The result showed that Gs, Pn and WUE ofB. glabra leaves increased with enhanced PFD prior to reaching the maximum value, and then decreased gradually, and they reached the maximum value under the PFD of 2 000, 1 500, 300 μmol·m^-2·s^-1 respectively. The Tr always increased with enhanced PFD. Gs and Tr decreased with the increased CO2 concentration, on the contrary, Pn and WUE significantly increased. Gs, Pn and Tr increased with time and topped at 13：00, then gradually decreased, and the diurnal variation of Gs, Pn and Tr demonstrated unimodal distribution, but WUE had no distinctive diurnal variation.