不同生境中头花蓼光响应曲线优化及光合参数变化规律

The Changing Rules on Photosynthetic Parameters and Light-response Curves Optimization of Polygonum capitatum-Buch.-Ham.ex D.Don in Different Habitats

在黔中杉木-白玉兰次生林内,利用Li-6400便携式光合测定仪对林窗、林缘和林下3种生境中生长的头花蓼光响应曲线进行测定,采用直角双曲线模型、直角双曲线修正模型、非直角双曲线模型和指数模型对光响应曲线进行了拟合,旨在优选头花蓼的光响应曲线模型及分析不同生境中的光合参数变化规律。结果表明直角双曲线修正模型是拟合头花蓼在3种生境中的光响应曲线最优模型。林下、林缘和林窗光饱和点(Isat)分别为1780.4、1201.4和808.4μmol·m^(-2)·s^(-1),光补偿点(Ic)的相应值为63.5、33.6和34.2μmol·m^(-2)·s^(-1),初始量子效率(α)的相应值为0.026、0.024和0.058,暗呼吸速率(Rd)的相应值为1.7、0.8和2.0μmol·m^(-2)·s^(-1),最大净光合速率(Pnmax)的相应值为13.7、9.5和7.5μmol·m^(-2)·s^(-1)。不同生境中头花蓼光饱和点和净光合速率的变化趋势为林下>林缘>林窗、光补偿点为林下>林窗>林缘、初始量子效率和暗呼吸速率为林窗>林下>林缘,表明头花蓼在林下具有较高的光合产物积累能力和耐荫性,适宜林下种植。

In secondary forest of Chinese fir-Magnolia in the middle area of Guizhou,aportable Li-6400 photosynthesis measuring system was used to explore light-response curves of Polygonum capitatum-Buch.-Ham.ex D.Don in three natural habitats with different light conditions,specifically canopy gap,edge and understory habitats.To optimize the light-response curves and analyze the change rules of photosynthetic parameters of Polygonum capitatum-Buch.-Ham.ex D.Don in different habitats,four lightresponse curve models were chosen,which included rectangular hyperbolic model（RHM）,modified rectangular hyperbolic model（MRHM）,non-rectangular hyperbolic model（NHM）,and exponential model（EM）to fit the light-response curves.The results showed that the MRHM provided a best model for the light-response curve.The photosynthetic parameters in 3habitats were estimated.Light saturation points（Isat）of the habitats were 1780.4,1201.4 and 808.4μmol·m^-2·s^-1 respectively;Light compensation points（Ic）were 63.5,33.6 and 34.2μmol·m^-2·s^-1;Initial quantum efficiency（α）in understory habitat were 0.026,0.024 and 0.058;Dark respiration rates（Rd）were 1.7,0.8and 2.0μmol·m^-2·s^-1;Maximum net photosynthetic rates（Pnmax）were 13.7,9.5and 7.5μmol·m^-2·s^-1.The trend of Isat and Pnmaxshowed understory〉edge〉gap;the trend of Ic showed understory〉gap〉edge;the trend ofαand Rd showed gap〉understory〉edge.These data indicated that Polygonum capitatum-Buch.-Ham.ex D.Don in understory habitat have more photosynthetic product accumulation and shade resistance,and it is suitable for planting under the forest.