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对美洲黑杨×欧美杨Ｆ_１代１３个无性系及亲本Ｉ－６９杨的一级分枝特性、生长、干形指标分层次进行系统研究。生长和一级分枝特性在无性系间存在较大差异；相关及通住分析结果表明：上层分枝较直立、中下层分枝趋于平展；上、中层分枝较短，较少；下层分枝较长，较多；上、中层小枝稀少而下层小枝浓密的尖塔形分枝结构是美洲黑杨×欧美杨Ｆ_１无性系的理想冠型。综合生长、干形及一级分枝特性可将该批无性系系统归为三类。
The first-level branch characteristics, growth and dryness index of thirteen clones and I-69 poplars of Populus × sibirica × Oryza sativa × Oryza sativa F_1 were systematically studied at different levels. The results showed that: the upper branches were more upright, the middle and lower branches tended to spread; the upper and middle branches were shorter and less; the lower layers Branches longer and more; upper and middle branchlets sparse and the lower spire thick spire-like branch structure is black poplar × Europe and the United States Yang F_1 clonal ideal coronal. This batch of clonal systems can be grouped into three categories with integrated growth, dry and primary branching characteristics.