<正>以杨树无性系797杨（Populus deltoides×P. euramericana）1年生苗为材料，对不同器官蛋白质含量与硝酸还原酶、谷氨酰胺合成酶、蛋白酶等3种氮代谢关键酶的动态变化与关系进行了研究。结果表明：杨树不同器官（木质部、皮层、根部）蛋白质含量在芽萌发期间（4月中旬）最低，木质部和皮层是杨树越冬期间贮藏蛋白质的主要贮存场所，根部相对较低。叶片和根部硝酸还原酶（NR）活性分别在9月初和10月中旬达到最大，落叶前后明显下降。叶片谷氨酰胺合成酶（GS）活性在5月中旬和10月中旬有两次高峰，与蛋白质变化趋势一致，而根部在芽萌发期间达到最大，与蛋白质变化趋势相反，两部位GS活性落叶前后明显下降。根部蛋白酶在春季芽萌发期间随着贮藏蛋白质的降解其活性逐渐上升，落叶前后，亦呈上升趋势，与蛋白质含量呈显著的相关关系。

The growth and certain physiological characters of Phoebe ckekiangensis seedlings under various soil moisture stress were studied. With the increasing of soil moisture, the individual leaf area,the leaf dried mass per seedling,the leaf fresh mass per seedling and leaf area per leaf dried mass(LAM)increased, but the leaf thickness and succulence degree decreared; The content of leaf chlorophyll was sensitive to soil moisture,under 5 kinds of different soil moisture status and the content of leaf chlorophyll was distinct. The drought and inundation were much destructive to the synthesis of both chlorophyll a and chlorophyll b. Under the light drought condition, the change of the containing water content, water saturation deficit and water potential were not evident, but under the serious drought condition, the containing water content and water potential fell, the water saturation deficit increased;the soil moisture status affected the net photosynthetic rate(Pn), serious drought would result in the smaller Pn, and seedlings’growth slowed down.