为了探索美洲黑杨物候性状遗传变异水平与利用潜力，开展基因资源评价，提供杨树定向遗传改良育种材料，对60个引种美洲黑杨无性系苗期的8个物候期进行观测分析。结果表明：（1）各无性系物候特征存在较大差异，展叶盛期差异最大，变异系数为14.97%，最小的是落叶末期，为3.83%；（2）展叶盛期出现的时间最分散，落叶末期相对集中，苗木生长前期物候特征是影响生长期长短的主要因素；（3）通过主成分分析将物候期分为3类典型，即萌芽期、展叶盛期和落叶期；（4）对各无性系物候出现时间变量进行聚类分析，将60个无性系分成4类。

In order to provide directionally genetically improved breeding materials of poplar by exploring the phenological traits genetic variation level and its development potential of Populus deltoides and carry out the resource evaluation, the author observed and analyzed 8 phenological phases in seedling period of 60 Populus deltoids clones introduced from America. The results showed that: (1) there was obvious difference in phonological character among clones, especially in lamina stage and late deciduous stage, with the largest variation coefficient of 14.97% and the minimum of 3.83% respectively. (2) The time of lamina stage was most scattered while that of late deciduous stage was most concentrated. The phonological character in the early stage of seedling growth was the main factor influencing the length of growing season. (3) By principal component analysis, the author classified phenological phases into 3 typical periods, including germination stage, lamina stage and deciduous stage. (4) The author classified 60 clones into 4 types by using clustering analysis in phenological time variables of clones.