光合作用光响应曲线模型选择及低光强属性界定

Selection of Models of Photosynthesis in Response to Irradiance and Definition of Attribute of Weak Light

采用抛物线、直角双曲线、非直角双曲线及直角双曲线修正式等数学函数对金沙江干热河谷3种不同类型植物材料的光合光响应曲线进行了拟合,提出一种分段函数用以拟合实测值并求算光合作用参数,构建了一种有关表观光合量子效率求算的弱光区域的确定方法,得到3点主要结论:(1)5种拟合方式中,分段函数与直角双曲线修正式对3种不同类型的光合光响应曲线均具有良好的拟合效果;(2)直角与非直角双曲线拟合得到的光合参数Pmax、LCP、Rd与实测值接近,但对LSP的估计值总是远低于实测值,直角双曲线修正式适合用于出现光抑制现象的曲线的模拟及其光合参数的求解,但无法得到饱和趋近型曲线的光合特征参数,分段函数求解的不同类型曲线的特征参数均与实测值较为接近;(3)以光合光响应曲线上光能利用效率的下降位点来界定植物表观光合速率随光强呈线性增长的弱光区域是可行的,且具相当的理论可释性。

Parabola, rectangular hyperbola, non-rectangular hyperbola, modified rectangular hyperbola and a subsection function were adopted to model the light-response curve for three different types of vegetations in the dry-hot river valley of Jinsha River, and a method was built to confirm the weak light region which related to apparent quantum yield of photosynthesis. Three main conclusions were gotten： （1）In five simulation methods, only subsection function andmodified rectangular hyperbola had good simulation effect for three different types of light response curves; （2）The parameters Pmax ,LCP, and Rd from rectangular hyperbola and non-rectangular hyperbola were near to the observations, but the estimates of LSP were always far lower than the observations, modified rectangular hyperbola was adapted tomodel the curves with phenomenon of light restrain and the estimation of photosynthetic parameters, but this method could not get the photosynthetic parameters for up-raising curve, the parameters estimated by subsection function for different types of curves were all near to the observations; （3） It was relatively theoretical to view the light range divided by thedescending point of light-using efficiency on light response curve as the weak light range, the apparent quantum yield of photosynthesis was often lowly estimated when the weak light region could not be confirmed.