河西走廊沙漠泡泡刺群体光合特征及其与环境因子的关系

以河西走廊沙漠典型的荒漠植物泡泡刺群落为材料,运用LI-8100土壤碳通量测定系统与改进的同化箱联合对其7月和8月中旬的群体光合作用进行了测定,分析群体光合速率与立地环境因子的关系,探讨泡泡刺群体对干旱荒漠环境的光合适应机制。结果表明,7月中旬泡泡刺的土壤呼吸速率和蒸发速率均高于8月中旬,而其同期群体光合速率和水分利用效率也显著高于8月中旬。两时期的光合有效辐射是影响泡泡刺群体光合速率的主要因子,于7、8月中旬对泡泡刺群体的光合速率起着直接作用;同时,实验地8月中旬的空气相对湿度也能通过与大气温度以及光合有效辐射的相互作用对泡泡刺群体的光合速率产生较大影响。在7月中旬高温强光环境下,泡泡刺的群体光合速率高于8月中旬,从而说明泡泡刺对高光强、高温的荒漠环境具有较好的适应性。

Relationship between Canopy Photosynthesis Characteristics of Nitraria sphaerocarpa and Environmental Factors in Hexi Corridor Desert

Nitraria sphaerocarpa Maxim.is a typical desert plant,which often forming N.sphaerocarpa bubbles with varying sizes.To further explore the photosynthetic adaptation mechanism of N.sphaerocarpa canopy for the arid desert environment,we use the measurement system of LI-8100 carbon flux and the modified assimilation chamber to study the photosynthetic characteristics of N.sphaerocarpa canopy in the mid-July and mid-August.The results showed that:the soil respiration rate and soil evaporation rate in mid-July were both higher than those in mid-August;the canopy photosynthetic rate and water use efficiency in mid-August decrease compared with those in mid-July,and the difference was significant (P<0.05).Path analysis between canopy photosynthetic rates of N.sphaerocarpa and environmental factors indicated that photosynthetic active radiation was the major factor to affect canopy photosynthetic rates of N.sphaerocarpa,and play a direct role in canopy photosynthetic rates in mid-July and mid-August;meanwhile,the interaction of air relative humidity,air temperature and photosynthetic active radiation also has a greater influence on canopy photosynthetic rates of N.sphaerocarpa in mid-August.Canopy photosynthetic rate of N.sphaerocarpa in mid-July under high temperature and strong light environment was higher than that in mid-August,which indicated that N.sphaerocarpa had a highly adaptability to the high temperature and light intensity in desert environment.