揭示川滇高山栎的光合特性对磷添加的响应机制,可为川滇高山栎的优质高效栽培和种质评价提供数据支持。以1、3 a生川滇高山栎幼苗为研究对象,分别设置对照(0,未添加)、低磷(0.5 g/株)、中磷(1.0 g/株)、高磷(2.0 g/株)4个磷添加处理,采用Li-6800便携式光合仪测定光响应曲线及光合参数;选用直角双曲线模型、非直角双曲线模型与叶子飘模型3 种光合模型对光响应曲线进行拟合,筛选适用于川滇高山栎叶片的最优光响应曲线模型;并对比分析不同磷添加水平下幼苗的光合参数差异,明确磷添加对其光合特性的调控效应,揭示川滇高山栎光合特性对磷添加的响应机制。结果表明:1)叶子飘模型在所有处理组中均表现最优,其决定系数(R²)、残差平方和(RSS)和均方误差(MSE)的值最低,拟合得出的最大净光合速率(P_nmax)等参数与实测值接近程度最高;2)不同处理组间的光合参数均有显著差异,1 a生低磷添加处理组的P_nmax最大,3 a生对照组的光饱和点(LSP)最大,1 a生对照组的表观量子效率(α)最高,3 a生低磷添加处理组的光补偿点(LCP)最低;3)磷添加明显增强了3 a生川滇高山栎幼苗的“光午休”现象。叶子飘模型的特征参数及拟合效果均优于其他2个模型,可作为川滇高山栎光响应曲线的最佳拟合模型;1 a生川滇高山栎幼苗在低磷添加处理下的光合生理最优。研究结果可为该物种的优质高效栽培及种质评价提供科学数据支撑。

By revealing how Quercus aquifolioides responds to phosphorus(P)addition in terms of photosynthetic characteristics,data support for its high-quality and efficient cultivation and germplasm evaluation were provided.With Quercus aquifolioides seedlings of different forest ages as the research object,we set up gradient phosphorus addition treatments and determined the leaf light response curves and photosynthetic parameters using a Li-6800 portable photosynthesis system.Three photosynthetic models were selected to fit the light response curves,and the optimal model suitable for the leaves of Q.aquifolioides was screened out based on the fitting parameters.The differences in photosynthetic parameters of seedlings under different phosphorus addition levels were compared and analyzed to clarify the regulatory effect of phosphorus addition on their photosynthetic characteristics,thereby revealing the response mechanism of photosynthetic characteristics of Q.aquifolioides to phosphorus addition.The results showed that:1)the leaf drifting model performed the best in all groups,with R²>0.98.The values of RSS and MSE were the lowest,and the fitted parameters such as maximum net photosynthetic rate(P_nmax)were closest to the measured values.2)There were significant differences in photosynthetic parameters between different treatment groups.The P_nmax was highest in the one-year low-P addition group,the light saturation point(LSP)was highest in the three-year control group,the apparent quantum efficiency(α)was highest in the one-year control group,and the light compensation point(LCP)was lowest in the three-year low-P addition group.3)Phosphorus addition significantly enhanced the midday depression of photosynthesis in three-year Q.aquifolioides seedlings.Based on comprehensive analysis,the characteristic parameters and fitting effect of the leaf drifting model are superior to those of the other two models,and it can be used as the best fitting model for the light response curve of Q.aquifolioides.The photosynthetic physiology of one-year high-mountain oak seedlings in Sichuan and Yunnan was optimal at a phosphorus addition concentration of 0.5 g per plant.The results provide a scientific basis for the high-quality and efficient cultivation and germplasm evaluation of this species.