对北京昌平和河北廊坊13个黑杨派无性系引种试验林5~6年生苗木生长性状开展遗传变异分析，并对河北廊坊试验林生长性状与3年生苗木上、中、下3个冠层水平上叶片解剖性状和气孔性状进行相关性分析和多性状综合评价，以用于无性系生长性状间接选择，从而提高选择效率和缩短育种周期。

选用2根1干、规格一致的黑杨派无性系苗木在北京昌平和河北廊坊营建无性系对比试验林，株行距分别为3 m×4 m和3 m×5 m，完全随机区组试验设计，3次重复。对两个地点5~6年试验林测定生树高和胸径，并进行多因素方差分析。在河北廊坊试验林3年生各无性系每一区组选2株平均木，依照树冠自然分枝轮序，由上至下依次分上、中、下层，在各冠层南面方向上各取1个代表性一级分枝，由顶端向下选取第6~10个叶片中1个完整、成熟叶片，测定叶片解剖性状（栅栏组织、海绵组织、总厚度）和气孔性状（气孔密度与长度），对生长性状与不同冠层叶片性状进行相关性和主成分分析。

两个地点无性系生长性状遗传参数比较结果表明：北京昌平性状变异系数（15%~47%）大于河北廊坊（13%~30%），广义遗传力和重复力均小于河北廊坊，除了北京昌平树高广义遗传力（0.03）和重复力（0.24）均最小，两地点其他生长性状广义遗传力和重复力均大于0.32和0.82。方差分析结果表明，不同无性系间生长性状差异均为极显著，不同地点间生长性状差异为显著或极显著，且除6年生苗的材积外，其他性状的地点与无性系间交互效应显著或极显著，相同无性系在两个地点间性状差异显著，其中，Br杨、Ti杨、La杨、Por杨和108杨5～6年生苗木胸径和材积在两地间的差异显著。相关分析结果表明，5～6年生苗木胸径和材积与不同冠层叶片上表面气孔密度之间呈显著负相关，与叶片解剖性状和其他气孔性状间相关性不显著。生长性状和叶片性状主成分分析（PCA）结果表明，生长性状与3个冠层叶片性状（共计11个性状）前4个主成分累积贡献率分别为85.5%、87.2%、90.7%，以前2个主成分为综合指标，可将13个无性系分为3类，其中生长量大的一类有8个无性系，其叶片厚度较大，上表皮气孔密度和海绵组织厚度较小。

黑杨派无性系5~6年生时胸径和材积主要受遗传效应和一般环境效应影响，且生长性状基因型与环境互作效应较强，其中，Br杨、Ti杨、La杨、Por杨和108杨生长性状受环境影响程度大于其他无性系。胸径和材积与不同冠层叶片上表面气孔密度显著负相关，叶片气孔性状可用于黑杨派无性系生长性状的间接选择。

Thirteen clones of Populus Section Aigeiros (poplars) mainly introduced from Italy were studied after growing seasons of the 5? and 6?year at the field test plantations in Changping, Beijing City, and Langfang, Hebei Province. Genetic variation analysis on the growth traits of clonal plantations at two sites was carried out. Growth traits, anatomical traits, and stomatal traits of leaves from three different crown positions of the sample trees in Langfang were investigated for correlation analysis and a comprehensive evaluation of multiple traits was carried out to improve selection efficiency and breeding.

Uniformly rooted young trees with 1?year?old stems and 2?year?old roots were established using the completely randomized block design of three blocks at Changping and Langfang in the springs of 2005 and 2008, respectively. For the field trials of Changping and Langfang, 10 to 20 and 25 individuals per clone were planted in each block at spacings of 3 m×4 m and 3 m×5 m. The diameter at breast height(DBH) and height were measured for each tree after growing seasons of the 5th and 6th year at two sites and the stem volume was calculated with the formula from the tree volume table. Growth traits were analyzed by multivariate analysis of variance. Two average sample trees were selected from each block per clone in the third growing season of plantation at Langfang. According to the top?down order of natural branching, the canopy was divided into 3 layers, i.e. upper, middle and lower canopy. A representative branch was selected from the first?order branches on the south side at each canopy position of each average tree. One mature leaf was sampled from the sixth to tenth branches at three different canopies of each sample tree of Langfang. Leaf anatomy (thickness of palisade and spongy parenchyma layers in total leaf) and its stomatal traits (density and length) were measured in the laboratory after collecting the leaves in the field trial. Correlation analysis and principal components analysis (PCA) were performed with 11 traits including the growth traits (DBH, stem volume) and leaf traits at the upper, middle and lower canopy position, separately.

The comparison of genetic parameters among growth traits at two sites showed that variation coefficient of traits at Changping (15%-47%) were more than those at Langfang (13%-30%) and the broad sense heritability and the repeatability at Changping were less than those at Langfang. The broad sense heritability (0.03) and the repeatability (0.24) of tree height at Changping were the minimum, while the broad sense heritability and the repeatability of other growth traits in two sites were greater than 0.32 and 0.82. The results of multivariate analysis of variance show that, the difference of growth traits among different clones was significant. There was significant difference of growth traits between two sites. In addition to the volume at 6?year?old, the interaction effect of other traits between clones and sites was significant or extremely significant. The growth traits of the same clone were significantly different between two sites, among which the DBH and stem volume of five clones (Br, Ti, La, Por and 108) were significantly different between two sites. The correlation analysis results showed that the DBH and stem volume were negatively correlated with abaxial stomatal density at three canopy positions, and were not significantly correlated with other leaf traits. The results of PCA between growth traits and leaf traits showed that the main planes of PCA (PC1, PC2, PC3 and PC4) of 11 traits established for upper, middle and lower canopy positions independently explained 85.5%, 87.2% and 90.7% of the variability, respectively. With PC1 × PC2 plane as factors, the first principal component was the index of growth character. The second principal component was positively correlated with leaf anatomical traits, and negatively correlated with leaf stomatal density and length of the lower epidermis. However, the contribution rate of leaf anatomical traits was the largest; therefore, the second principal component was the relevant index for leaf anatomical traits. Based on the results of PCA, the 13 clones can be divided into three categories: the first class clones (Por, 111, 107, 108, Me, 36, 50 and Be) have greater growth and smaller leaf thickness, leaf epidermis stomatal density, and sponge tissue thickness than the other classes. The classification between the second and third class varied from different canopies. According to PCA of growth traits and leaf traits at the upper and middle canopy, the classification can be divided into the second class clones (Ta and La) and the third class clones (Br, Ti and 109). According to PCA of growth traits and leaf traits at the lower canopy, the classification can be divided into the second class clones (Ti, 109 and La) and the third class clones (Br and Ta). The second and third class clones have smaller growth and greater adaxial stomatal density and spongy parenchyma thickness than the first class clones.

The 5? and 6?year?old DBH and stem volume of Section Aigeiros clones were mainly affected by genetic effects and general environmental effects. There were significant differences of growth traits between the sites and the interaction between the sites and the clones, indicating that the genotypes had strong interaction effect with the environment on the growth traits. Growth traits of five clones (Br, Ti, La, Por and 108) were more affected by environment than these of other clones. There was a significant correlation between DBH and tree volume with abaxial stomatal density. The results of these studies showed that the establishment of a joint selection system for multi?trait perennials was of great significance to the research on selective breeding of poplars.