内蒙古羊草草原主要建群草种的光合参数

Photosynthetic Parameters of Major Grass Species in Inter Mongol China Plain

为了准确评价草原的光合生产能力,用LI-6400便携式光合测定仪,人工控制光强和CO2浓度,测定了内蒙古羊草草原的优势植物种大针茅(Stipa grandis)、冰草(Agropyron cristatum)、羊草(Lutmus chinensis)叶片光合速率对光强和CO2的响应曲线,阐述了光合作用对光和CO2浓度的响应特征。结果表明,3种牧草叶片光合速率随光强或CO2浓度的增大而升高,可以用米氏方程对其进行描述。由此确定了3种牧草的光合参数:表观量子效率、最大羧化效率、光补偿点、近光饱和点、CO2补偿点、CO2饱和点、暗呼吸速率、光呼吸速率、潜在最大光合速率等。3种牧草的光合参数差异显著,大针茅的表观量子效率、最大光合速率、CO2饱和点高,CO2补偿点低,可以宽幅度利用CO2。而羊草的初始羧化效率最高,具有较高的RuBPCase酶活性。综合考虑各个参数,大针茅的光合能力更强。

In order to truly appraise photosynthetic productivity of plain, the response of photosynthetic rate of Stipa grandis, Agropyron cristatum and Lutmus chinensis to light intensity and CO2 concentration was studied using Li-6400 in Inter Mongol China plain. Generally, photosynthetic rate of 3 grass species increases with light intensity （PPFD） or CO2 concentration, which can be expressed by Michaelis-Menten function. Photosynthetic parameters included apparent quantum yield, apparent carboxylation efficiency, light compensation point, light saturation point, CO2 compensation point, CO2 saturation point, dark respiration rate, photorespiration rate and maximum photosynthetic rate, which were calculated from those Michaelis-Menten functions, and were found to differ significantly among different species. Stipa grandis may possess high photosynthetic productivity as they displayed higher apparent quantum yield, maximum photosynthetic rate, CO2 saturation point and lower CO2 compensation point, compared with the other species. While, Lutmus chinensis possess high RuBPCase activity as they displayed higher apparent carboxylation efficiency.