毛竹林下苦参和决明幼苗光合作用光响应模型比较

Comparison of Photosynthetic Light Response Models of Sophora flavescens and Catsia tora under Phyllostachys edulis Seedlings

[目的]探讨苦参和决明对不同立竹密度毛竹林下光环境的适应规律,为毛竹林下苦参和决明的复合经营提供理论参考。[方法]以毛竹林下种子播种的固氮植物苦参和决明幼苗为试验材料,选择立地条件和经营水平一致,立竹密度为低(1 600±200株·hm-2)、中(2 400±200株·hm-2)、高(3 200±200株·hm-2)3种试验毛竹林,采用直角双曲线模型、非直角双曲线模型、直角双曲线修正模型和指数模型4种光合响应模型拟合。[结果]表明:在不同立竹密度的毛竹林下,苦参和决明拟合的均方误差(MSE)、平均绝对误差(MAE)值均是直角双曲线修正模型最小,直角双曲线模型最大,MSE、MAE预测值也是直角双曲线模型大于直角双曲线修正模型;4种模型拟合的苦参和决明的初始量子效率(α)、最大净光合速率(Pnmax)、暗呼吸速率(Rd)、光补偿点(LCP)存在差异,苦参和决明在不同立竹密度的毛竹林下4种模型拟合的α值均不同,Pnmax、Rd、LCP总体上是直角双曲线模型最大,直角双曲线修正模型较小,并且只有直角双曲线修正模型可以直接计算出光饱和点(LSP);在一定的光强范围内,除直角双曲线模型外,其余3种模型拟合的苦参和决明净光合速率(Pn)随着光强的增强而增加,但光强超过光饱和点(LSP)后,净光合速率(Pn)随着光强的增强而降低,且不同立竹密度的毛竹林下苦参和决明4种光响应拟合模型的决定系数R2值均是直角双曲线修正模型最大。[结论]不同立竹密度毛竹林下苦参和决明的光响应曲线用直角双曲线修正模型拟合更精确。

[ Objective ] To Compare the photosynthetic light response physiological parameters of four fitting models and identify the adaptability of Sophora flavescens and Catsia tora, so as to provide theoretical reference for the com- pound management of S. flavescens and C. tora under moso bamboo （Phyllostachys edulis）. [ Method ] The S. fla- vescens and C. tom seedlings, the nitrogen-fixing plants, were investigated under low （ 1 600 ± 200 stein·hm^-2 ） and medium （2 400±200 stem · hm^-2） and high （3 200±200 stem· hm^-2） density of moso bamboo with same sites condition and management level. The light response curves of S. flavescens and C. tora leaves were measured and fitted, as well as analyzed by rectangular hyperbola, non-rectangular hyperbola, modified rectangular hyperbola model and exponential model. [ Result ] The values of fitted mean-square error （MSE） and mean absolute deviation （MAE） of S. flavescens and C. tora were the smallest for the modified rectangular hyperbola model and largest for the rectangular hyperbola model. The MSE and MAE estimated by rectangular hyperbola were more than that by modified model under different stand density of moso bamboo. The light response physiological parameters of or, P and LCP were different in the iour models, and both the fitted values of α of S. flavescens and C. tora were different under different bamboo stand density, and the P Rd and LCP estimated by rectangular hyperbola were more than the measured values, and these photosynthetic parameters estimated by the modified rectangular hyperbola model was close to the measured values. At the same time, only the modified model enables directly calculating the Lsp. Except for the rectangular hyperbola model, there was a certain law of S. flavescens and C. tora, namely, the net photosynthetic rate increased with the light intensity, then decreased while exceeding the saturation point, and the determinant R2 of modified rectangular hyperbola model was the largest in the four fitted models. [ Conclusion ] The photosynthetic light response curve of S. flavescens and C. tora fitted by modified rectangular hyperbola model is more accurate than that fitted by the other models under different stand density of moso bamboo.