青绿苔草光合作用日变化及季节动态

Daily and seasonal variation of photosynthetic characteristics of Carex leucochlora

利用Li-6400便携式光合分析仪研究了青绿苔草(Carex leucochlora)在5、8、10月的光合日变化和光合-光强响应曲线。结果表明,青绿苔草光合特性受季节影响较大。5月光合作用特性中的净光合速率、蒸腾速率、气孔导度等参数日变化均为双峰型曲线,存在光合"午休"现象,而8、10月均为单峰型曲线。不同季节光合特性的变化与环境有密切关系,最大净光合速率与土壤含水量、气温相关性较高。青绿苔草蒸腾速率和气孔导度较低,水分利用效率较高,表明青绿苔草较耐旱节水。不同月份青绿苔草净光合速率较低,5、8月份光补偿点小于20μmol·m-2·s-1,光饱和点也小于1 000μmol·m-2·s-1,10月光补偿点也仅为30μmol·m-2·s-1,光饱和点为1 047μmol·m-2·s-1,为典型的耐阴植物特征,表明青绿苔草具有较强的耐阴性。

Daily variation of photosynthetic characteristics and light-photosynthetic rate response curve of Carex leucochlora were analyzed using Licor-6400 portable photosynthesis system in May, August and October. The results showed that the daily variation of net photosynthetic rate, transpiration rate and stomatal conductance in leaves presented two-peak curve and midday depression in May and presented single-peak curve in both August and October. Photosynthetic characteristics were extensively affected by environmental conditions of different months. The maximal net photosynthetic rate had closer correlation with soil moisture and air temperature. The lower transpiration rate and stomatal conductance and higher water utilization efficiency indicated that C.leucochlora was a drought-resistant plant species. Net photosynthetic rate of C.leucochlora was low in different months. Light compensation points were less than 20 μmol·m^-2·s^-1ight saturation points were less than 1 000 μmol·m^-2·s^-1 May and August. Light compensation points were 30 μmol·m^-2·s^-1d light saturation points were 1 047 μmol·m^-2·s^-1 October which indicated that C.leucochlora was a typical shade-tolerance plant.