不同光照环境下荷花叶片光合光响应模型比较

Comparison of light response models of photosynthesis in Nelumbo nucifera leaves under different light conditions

以上海荷花品种‘伯里夫人’为试验材料,设置全光照和林下遮荫(50%全光照)2种不同的光照环境,采用4种光响应模型拟合分析荷花叶片净光合速率光响应过程,比较不同光照下适宜的光响应模型,研究荷花品种对遮荫环境的适应规律.结果表明:4种模型对荷花叶片光合作用光响应过程拟合效果的优劣顺序为:直角双曲线修正模型>指数模型>非直角双曲线模型>直角双曲线模型,后3种模型均为没有极值的函数,不能直接求得最大净光合速率(Pn max)和光饱和点(LSP).直角双曲线修正模型对LSP、Pn max、暗呼吸速率(Rd)和光补偿点(LCP)等光响应参数表现出最佳的拟合效果,拟合值与实测值相对误差最小.随光强减弱,荷花主要的光合生理参数均降低,其中,Rd下降幅度显著,其他参数变化不显著.说明荷花对适度弱光环境具备一定的适应能力,表现出良好的光合适应性反应与调节,能够维持植株的正常生长.

The light responses of Nelumbo nucifera ‘ Boli Furen＇ , a local N. nucifera species was investigated under full light and 50% shading conditions in Shanghai The net photosynthetic ratelight response curves of N. nucifera leaves were fitted and analyzed through four light response models to identify the best-fit models of different light conditions and explore the adaptability of N. nucifera to shading environment. The results showed that the sequence of fitting effect of the four light response models was in descending order of modified rectangular hyperbola model 〉 exponen- tial model 〉 non-rectangular hyperbola model 〉 rectangular hyperbola model. The latter three mod- els had no extreme values, and could not directly and accurately provide values of light saturation point （LSP） and maximum net photosynthetic rate （Pn max）.In contrast, the modified rectangular hyperbola model showed the best fit for LSP, P dark respiration rate （Rd ） and LCP resulting in the minimum relative errors between the measured and fitted values. Light response parameters of N. nucifera declined with the decreasing light. There were no significant differences between full light and shade treatments except for Rd. It was indicated that N. nucifera had good photosynthetic adaptive response and adjustment to weak light to maintain normal growth.