Objective  This paper aims to analyze the inheritance and variation rules of allotriploid poplar, explore the effects of ploidy level, gender, genotype and environmental effects on the variation of short branch functional leaf and stomatal characters in full-sib diploid and triploid hybrids between section Tacamahaca and sect. Aigeiros of Populus.

  Method  In this study, variations of short branch functional leaf and stomatal traits between full-sib diploid and triploid hybrids of 10-year-old clone experimental forest of P. pseudo-simonii × P. nigra ‘Zheyin3#’ and P. × beijingensis were analyzed.

  Result  Clonal repeatability of short branch functional leaf and stomata was high, ranging from 0.789 to 0.960, which was controlled by strong heredity and had little environmental impact. There were very significant differences among clones in leaf and stomatal traits. The variation coefficient of leaf width and stomatal width was lower, which was a relatively stable genetic feature among the tested traits. The leaf length, leaf width, leaf area, stomatal length and stomatal width of triploid were extremely significantly larger than those of diploid, and the stomatal density was extremely significantly smaller than diploids, while the petiole length and serration number of triploids were not significantly different from diploid. There was no significant difference in leaf and stomatal traits between different gender plants. Correlation analysis results showed that leaf length, leaf width, leaf area, stomatal length and width were very significantly positively correlated with ploidy level, stomatal density was very significantly negatively correlated with ploidy level, while petiole length and serration number were not significantly correlated with ploidy level. The variance contribution rate showed that the gender effect of clones had the least influence on leaf and stomatal characters; stomatal traits were mostly affected by ploidy effect, followed by genotype effect; leaf traits were mainly affected by genotype effect, followed by ploidy and environmental effects.

  Conclusion  The variation of short branch functional leaf and stomatal traits of full-sib hybrid between section Tacamahaca and sect. Aigeiros of Populus was mainly come from ploidy effect and genotype effect, but the influence of gender and environment was small. There were abundant trait variations among clones. It is necessary to carry out “large population, strong selection” breeding based on genetic determination in triploid breeding of Populus.