【目的】研究美洲黑杨‘I-69’杨(Populus deltoides ‘Lux’)×青杨(P. cathayana)F₁代初选无性系苗期表型性状指标的分化,解析不同性状分化的生物学和生态学意义,并对无性系进行类型划分,综合考虑无性系性状以及对应的目标用途,为应对干旱等条件下杨树造林的适地适树(无性系)选择提供参考。【方法】以江苏省宿迁市泗洪县半城马浪湖林场36个‘I-69’杨×青杨F₁代无性系3根1干苗为材料,调查苗木的生长量、叶片形态、气孔特征、侧芽萌发情况和分枝特性等17个指标,分析各指标的变异特征,并根据性状变化对无性系进行分类和评价。【结果】F₁代无性系的生长和表型指标均具有显著的分化,总体上呈连续的正态分布特征,其中侧枝数与侧芽萌发率的变异系数最大,分别达102.0%和93.5%。相关分析表明,苗木生长指标与叶片形态以及分枝特性指标显著正相关,但与叶片气孔特征无显著相关。叶面积以及叶干质量分别与叶片长宽比呈显著负相关,与上下表皮气孔密度比呈显著正相关。叶片长宽比与叶柄相对长呈显著负相关,同时也与上下表皮气孔密度比呈显著负相关。叶面积和叶干质量的异速生长指数为1.007 4,整体呈等速生长关系,与分枝特性等无相关关系。基于主成分分析方法,利用表型性状可以把36个F₁代无性系分为8类,不同类型具有独特的生长、分枝特性和潜在的抗旱性能。【结论】美洲黑杨和青杨杂交F₁代无性系表型性状变异丰富,通过早期判断可以针对不同气候和立地条件造林提供无性系选择的初步信息,其中类型Ⅳ中的4个无性系生长量最大、侧枝少,叶型和气孔特性等表型性状表现出一定的耐旱特征,可以选择用于在偏干旱的平原地区或山地进行进一步的适应性造林试验。

【Objective】 The variations in growth and phenotypic traits of the F₁ hybrid progenies of Populus deltoides ‘Lux’ × P. cathayana were investigated at the cutting-seedling stage to interpret their biological and ecological significance, and to classify the F₁ hybrid clones in order to evaluate the resistance of clones and their target uses comprehensively. The results can provide basic information for matching suitable poplar clones with afforestation sites under the background of climate change such as frequent drought. 【Method】 Using the cuttings with one-year stem and three-year root of 36 F₁ hybrid progenies in Bancheng-Malanghu Forest Farm of Sihong City, Jiangsu Province, 17 traits on seedling growth, leaf morphology, stomatal properties, and lateral branching characteristics were investigated and the variations of each trait were analyzed. Based on the trait variations, the 36 hybrid clones were categorized and evaluated for potential use on afforestation selection on different sites. 【Result】 The 36 F₁ hybrid progeny showed a significant variation on growth and phenotypic traits, expressing continuous normal distributions for each trait in general. Among all the traits, the number of lateral branches and the germination ratio of lateral buds showed the largest coefficients of variations as 102.0% and 93.5%, respectively. A correlation analysis showed that the traits related to growth were positively correlated with those related to leaf morphology and branching characteristics significantly; however, no significant correlation was found with stomatal properties. The single leaf area and dry mass were negatively correlated with the leaf length-to-width ratio, and positively correlated with the upper-to-lower ratio of leaf stomatal density significantly. The leaf length-to-width ratio was also negatively correlated with the relative length of petiole (the ratio of petiole length to leaf length) and the upper-to-lower ratio of leaf stomatal density significantly. Single leaf area and dry mass showed a constant scaling relation for all the 36 clones, with an allometric index of 1.007 4, which was not related to branching characteristics. Using a principal component analysis, the 36 F₁ hybrid clones were classified into eight categories with specific properties on growth, branching and potential drought resistance. 【Conclusion】The F₁ hybrid progenies of P. deltoides × P. cathayana have abundant variations in growth and phenotypic traits, which provides phenotype-function information for clone choice for afforestation under changing climate and site conditions at an early stage. The four clones in category Ⅳ have highest growth performances, few lateral branches, and phenotypic traits such as leaf morphology and stomatal characteristics that show drought tolerance, and are suitable for further adaptive afforestation experiments in arid plains or mountainous areas.