摘要
鼎湖山季风常绿阔叶林的主要优势乔木树种裂壳锥（Ｃａｓｔａｎｏｐｓｉｓｆｉｓｓａ （Ｃｈａｍ ｐ．ｅｘ Ｂｅｎｔｈ．） Ｒｅｈｄ．ｅｔＷｉｌｓ．）和荷木（Ｓｃｈｉｍ ａ ｓｕｐｅｒｂａ Ｇａｒｄｎ．ｅｔＣｈａｍ ｐ．）幼苗，盆栽于自然条件（ＣＯ２ 浓度３５０ μＬ·Ｌ－ １）或高ＣＯ２ 浓度为５００ μＬ·Ｌ－ １和空气ＣＯ２（３５０ μＬ·Ｌ－ １）的半开顶式气罩中。在生长最旺盛的６～９ 月份，高浓度ＣＯ２ 条件下生长的叶片，其光合速率比在自然条件下生长的提高７９％ ～９５％ 。当叶片在３５０ μＬ·Ｌ－ １和５００ μＬ·Ｌ－ １的ＣＯ２ 浓度下测定时，其光合速率无明显差异。高浓度ＣＯ２ 下生长的叶片其光合速率－ＣＯ２ 浓度响应曲线比对照（３５０ μＬ·Ｌ－ １）高，叶绿素和类胡萝卜素含量低，但叶绿素ａ 和ｂ 的比值及类胡萝卜素和叶绿素的比值不变。高浓度ＣＯ２ 下生长的叶片气孔导度明显降低。两种植物在８５ ｄ 的高浓度ＣＯ２ 的生长过程中。
Photosynthetic response of seedlings of two evergreen trees dorminant in a subtropical forest to long term elevated CO 2 were studied.Pot seedlings of Castanopsis fissa (Champ.) Rehd.et Wils. and Schima superba Gardn.et Champ.were grown in semi open chambers with ambient (350 μL·L -1 ) CO 2 concentration under natural light from June to September,1993.Net photosynthetic rate of the plants exposed to elevated CO 2 increased by 79%～95% than that of the plants in ambient CO 2 atmosphere. But no significant difference was observed when measurement was done at either CO 2 concentration,350 μL·L -1 or 500 μL·L -1 .The P n CO 2 concentration response curves of plants growing in elevated CO 2 were higher than that of plants growing in ambient (350 μL·L -1 CO 2). In addition,the chlorophyll and carotenoid contents dropped slightly and stomatal conductance decreased obviously under elevated atmospheric CO 2,while the ratios of chlorophyll a to b and carotenoid to chlorophyll were unaltered.The results indicated that downward acclimation of phetosynthesis did not appear in both plant species when they were grown under prolonged exposure to high (500 μL·L -1 ) atmospherie CO 2.
基金
国家自然科学基金
