<正>本文分析了Ⅰ-69杨×小叶杨和Ⅰ-69杨×欧洲黑杨F_1无性系干形性状的遗传变异度,结果表明对干形实行直接选择是可行的。为了充分挖掘干形改良的遗传潜力和为多世代育种提供理论依据,探讨了从树冠结构方面对干形实行间接选择的可能性。遗传相关分析提供了树冠各组成性状与干形的联系情况,通径分析具体剖析了它们的直接和间接作用,确立各F_1无性系干形改良的理想冠型。在比较不同性状组合的干形选择指数效果基础上,利用一个合理的选择式预测了各F_1无性系的干形。将干形选择效果与生长选择效果进行比较,具体评述了生长与干形同时进行改良的可能性。

This paper analysed the genetic variation of the stem form characters in 1-69 poplar × Simon poplar and 1-69 poplar × Nigra poplar F1 clones, which indicated that it is possible to select directly for stem form. In, order to tap adequately the potential of stem form improvement and to provide theoretical foundation for mult-generation breeding, the possibility of selecting indirectly for stem form from the tree crown structure was studied. The analysis of ge-notypic correlation provided the asseciations of different characters composing of tree crown to stem form and path-analysis analysed concretely their direct and indirect effects so as to determine the ideal crown form for stem form improvement of two different F1 clones. Based on the comparison among the results of selecting indexes of stem form of different characters combinations, the stem form estimates of different clones were taken by the most reasonable selection equations. By means of the comparison of the results of stem form selection to those of growth selection, the possibitity of improving simultaneously growth and stem form was concretely reviewed.