额济纳绿洲胡杨的光合特征及其对光强和CO_2浓度的响应

Photosynthetic characters of Populus euphratica leaves and response rate to light intensity and CO_2 concentration in Ejina oasis of Northwest China

以额济纳绿洲胡杨(Populus euphratica Oliv)为研究对象,用美国Li-cor公司生产的Li-6400便携式光合作用测定仪测定其光合速率的日变化及控制光强、CO2浓度和温度等环境因子,阐述了光合速率对光强和CO2浓度的响应特征。结果表明:在生长季胡杨阳叶光合速率的日变化呈现双峰曲线,具有明显的光合“午休”现象,但胡杨阴叶光合速率的日变化呈单峰曲线。光照、温度和CO2浓度皆对胡杨的光合作用有显著的影响。在控制环境条件下,光合速率随光强或CO2浓度的升高而增大,分别遵循Farquhar模型和Michaelis-Menten模型;在不同CO2浓度下,光饱和点随CO2浓度的升高而增大,表观量子效率和光补偿点则随CO2浓度的升高而减小,但在相同的CO2浓度条件下,阳叶的光补偿点高于阴叶;在不同光强下,表观羧化效率也随光的增强而增大。CO2补偿点随光强的增强而有所下降,且在同等光强条件下,阴叶的CO2补偿点大于阳叶。

The response of photosynthetic rate of Populus euphratica Oliv to changes in light intensity and CO2 concentrations was studied using a Li - 6 400 in Ejina oasis of Northwest china. The result showed that net photosynthetic rate in leaves of sunny positions for Populus euphratica Oliv appeared in curvilinear changes with double peaks and apparent middy depression diurnally, however, the leaves of shade positions appeared in curvilinear changes with single peaks. Light intensity, air temperature and CO2 concentration evidently affected net photosynthetic rate. In general, photosynthetic rates increased with light intensity and CO2 concentration and could be expressed by a Farquhar function and Michaelis - Menten function respectively. Light saturation point increased with CO2 concentration but apparent quantum yield and light compensation point decreased. Light compensation point of sunny leaves is higher than shade leaves at the same CO2 concentration. Similarly, apparent carboxylation efficiency increased with light intensity but CO2 compensation point decreased. And showed CO2 compensation point of shade leaves higher than sunny leaves at the same light intensity.