欧洲3种常见乔木幼苗在两种光环境下叶片的气体交换、叶绿素含量和氮素含量

在室内测定了分别栽培于全光照和20％光照条件下的垂枝桦Betulapendula，欧洲水青冈Fagussylvatica和欧洲白栎Quercusrobur幼苗叶片的光合作用－光响应曲线、叶片气孔导度、胞间二氧化碳浓度、水分利用效率，叶绿素含量和氮素含量，并分析叶片叶绿素含量和净光合速率的回归关系．20％光照条件引起净光合速率的光饱和点下降，叶片气孔导度和水分利用效率以及单位叶面积叶绿素含量降低，叶片的光合物质积累减少，但氮素含量上升．回归分析结果表明，叶片叶绿素含量与净光合速率成正相关．3种植物的幼苗对荫蔽条件有一定的适应性，其中B．pendula和Q．robur的耐荫能力比Fsylvatica强.

GAS EXCHANGE, CHLOROPHYLL AND NITROGEN CONTENTS IN LEAVES OF THREE COMMON TREES IN MIDDLE EUROPE UNDER TWO CONTRASTING LIGHT REGIMES

Measurements were made of photosynthesis-light response curves, leaf stomatalconductance, intercellular CO_2 concentration, water use efficiency (WUE), chlorophyll andnitrogen contents in leaves of 2- to 3-year old seedlings of Betula pendula, Fagus sylvaticaand Quercus robur potted under two contrasting light (full light and 20% full light) regimesin indoor condition in Germany in September, 1989. Regression relationship between netphotosynthetic rate and chlorophyll content was also analysed .The seedling grown under 20% full light condition showed a lower net photosynthetic rate and light-saturated point,lower stomatal conductance and WUE, lower chlorophyll content per fresh weight unit ofleaf and the reduced accumulation of dry matter compared to those grown under full light.A positive correlation was found between chlorophyll content and net photosynthetic rate.Seedlings of the three examined tree species could deal well with the shadiness under forest.Betula pendula and Quercus robur would be more capable of adaptation to shadyenvironment than Fagus Sylvatica.