互花米草成熟期光合作用日变化特征研究

Study on Diurnal Variation of Photosynthesis of Spartina alterniflora in Its Mature Stage

[目的]为互花米草的防治提供生理生态学依据。[方法]利用LI-6400型便携式光合仪测定成熟期互花米草光合生理特性的日变化及其与环境影响因子的关系。[结果]互花米草净光合速率（Pn）的日变化呈双峰曲线，7：00～9：00迅速升高，9：00左右达到1d中的最大值，9：00～13：00持续下降，出现明显的光合“午休”现象；气孔导度（叫）和蒸腾速率（Tr）的日变化均呈单峰曲线；胞间CO2浓度与净光合速率呈极显著负相关；光强、温度、气孔导度和蒸腾速率的峰值均出现在12：00。[结论]互花米草的光合“午休”现象受非气孔因素和气孔因素的共同影响。

[ Objective ] The study was to provide the physiological ecology basis for the control of Spartina alterniflora. [ Method ] The diurnal variation of photosynthetic physiological characteristics of S. alterrtiflora and its relationship with environmental impact factors in mature stage of S. alterniflora was determined by LI-6400 portable photosynthesis system. [Result] The diurnal variation of net photosynthetic rate （Pn） of S. alterniflora was bimodal curve. The Pn was increased rapidly at 7：00 - 9：00 am, it reached the highest at 9：00 am and decreased continuously at 9：00- 13：00, so obvious midday depression of photosynthesis appeared. The diurnal variations of stomatal conductance （Cd） and transpiration rate （Tr） were single peak curve. The intercellular CO2 concn had highly significant negative correlation with Pn. The peak values of light, temperature, stomatal conductance and transpiration rate were all appeared at 12：00. [ Conclusion] The midday depression of photosynthesis of S. alterniflora was common affected by non stomatal factors and stomatal factors.