提高CO2浓度对两种亚热带树苗叶片水分状况的影响

鼎湖山季风常绿阔叶林的主要优势乔木树种黧蒴和荷木的幼苗,盆栽于自然光照和人工调节CO₂浓度为500μl·L^-1或空气CO₂(340μl·L^-1)的气罩中3个月.在各自生长条件下测定,高CO₂下生长的黧蒴和荷木叶片平均气孔导度分别降低13%和20%,蒸腾速率下降20%和18%,水分利用效率提高1倍以上,不同CO₂浓度下的植物叶片气孔导度和蒸腾速率日进程曲线也有明显差异.处理后将幼苗置于自然条件下观测其后效应,第7d时处理间的气孔导度和蒸腾速率皆无明显差异

Effect of elevated CO2 concentration on leaf water regime of subtropical tree seedlings

Potted seedlings of Castanopsis fissa and Schima superba, two dominant species in monsoon evergreen broad leaf forest of Dinghushan, Guangdong Province, are grown in semi opened chambers with ambient(340 μl·L^-1) and elevatcd (500±50 μl·L^-1) CO₂ concentration under natural light for three months.The stomatal conductance of leaves grown in high CO₂ is decreased by 13% for C.fissa and by 18% for S.superba,and their transpiration rate is decreased by 20% and 18%, respectively. For these two species, their water use efficiency is increased by more than 100%. The diurnal courses of stomatal conductance and transpiration rate are quite different between plants grown in elevated and ambient CO₂. When all plants are put back to ambient CO₂ without chamber, no obvious difference of stomatal conductance and transpiration rate is observed on the seventh day.