<正>从北美一球悬铃木截冠植株上采当年生萌蘖枝条作为起始外植体进行组培试验，当用其茎段作为外植体诱导腋芽时，MS+NAA（0.1mg/L）+6-BA（1.0mg/L）+蔗糖（30g/L）为适合的培养基，而在系统研究基本培养基、植物激素等因素对北美一球悬铃木不定芽增殖的影响后发现：以DCR为基本培养基，添加NAA（0.1mg/L）+6-BA（1.0mg/L）+KT（0.3mg/L）+蔗糖（30g/L）可促进北美一球悬铃木不定芽的增殖，产生的不定芽生长情况良好、增殖系数高，是比较适合芽增殖的培养基。生根培养时，笔者在实验中设计了两条生根技术路线：一步法生根，将芽直接接种在含添加物R（150mg/L）的DCR培养基上；二步生根法，先将芽接种在含添加物R（60mg/L）的DCR培养基上15d左右，再转接至DCR基本培养基上。结果表明两条生根培养途径下的生根率均达100%。

Net photosynthetic rate (Pn), stomatal conductance (Co), internal CO2 concentra tion (Ci), chlorophyll content and leaf area were measured in leaves of Toona ciliata var. pubescens seedlings grown in pots with various shading and various soil water contents. The resuhs showed as follows: The diurnal variations of Pn were "twin-peaked" curve, and the peak value occurred at 10:00 and 16:00 or so. There was an obvious "midday depression" phenoraenon under full light and middle shading (60%), while it didn’t occur obviously under strong shading (80%). The diurnal variations of Ci were just opposite to Pn under the full light. Photosynthesis was the strongest when water content in soil was sufficient. The decreasing of Cond and even variation of Ci showed that the decreasing of Pn was related to non stomatal restriction factors after 10:00. With the increase of leaf area and chlorophyll content under shading, the leaves of T. ciliata var. pubescens had the higher utilization effi ciency on weak light. The results suggested that the control of soil water content and irradiance might help to promote the growth of T. ciliata vat. pubescens.