<正>研究了土壤干旱过程中北京东灵山辽东栎林4种木本植物(辽东栎Quercusliaotungensis,大叶白蜡Fraxinusrhynchophylla,柔毛绣线菊Spiraeapubescens和二色胡枝子Lepsedezabicolor)盆栽幼苗的净光合速率(Pn)、气孔导度(gs)、胞间CO2浓度(Ci)及叶肉导度(gm)的变化。结果表明:干旱引起Pn、gs以及gm降低,但两种乔木幼苗的Ci没有降低反而在严重干旱时出现增加,两种灌木幼苗的Ci保持相对稳定。说明干旱引起4种植物光合的下降主要是来自于非气孔因素gm的限制,而不是由于气孔的关闭引起对CO2供应的制约。

Effects of drought were investigated on net photosynthetic rate(P_n,μmol/(m~2·s)),stomatal conductance(g_s,mmol/(m~2·s)),subcelluar CO_2 concentration(C_i,μmol/mol) and mesophyll conductance to CO_2(g_m,mol/(m~2·s)) in potted seedlings of four woody species(Quercus liaotungensis and Fraxinus rhynchophylla,Spiraea pubescens and Lepsedeza bicolor)from Q.liaotungensis forest in Beijing Dongling mountain.The results showed that soil drought which caused decreases in P_n,g_s,and g_m.C_i was maintained stable in two shrubs during the whole drought duration,whereas it was stable in two tree species only under mild drought but increased under serious drought.This suggests that the limitation to photosynthesis under drought conditions was not entirely attributed to stomatal limitation,but mainly to non-stomatal limitation.