Abstract:

Objective: Variation of growth traits in 12 hybrid clones of Populus×euramericana in different environments was investigated to study the genotype by environment interaction. We screened superior genotypes that can be promoted for stable and high yield, summarized patterns of the interaction how varieties adapting to site conditions in the trials, and evaluated the discrimination and representation of the test sites. It aims to provide technical support for the follow-up work of the Populus×euramericana. Method: The test materials were 12 different genotypes of 3-year-old Populus×euramericana hybrid clones. Six test sites in Heishan, Luannan, Zhucheng, Yuncheng, Ningyang and Shishou were used in the trials. The tree height and DBH were measured, and the coefficient of variation and the mean were calculated for preliminary comparison. A mixed effect model was established using the ASReml-R package, and the predicted trait values were used to generate GGE biplots. Patterns of variation were analyzed and used to evaluate the test site and to select superior genotypes. Result: Overall, the variation is greater in DBH than in tree height, and the variation in Heishan and Shishou is larger. The statistics show that the growth traits of different genotypes behave differently under the same environment, and that the growth traits of the same genotype behave differently under different environments. The test by the mixed linear model shows that genotype, environment, and genotype-environment interaction have very significant (P < 0.01) effects on the tree height and DBH of Populus×euramericana in the early growth, and the effect brought by the block is also very significant (P < 0.01). The predicted values of the traits are extracted as GGE biplots, the fitting degrees are all above 80%, and the results are almost consistent with the actual situation. The GGE biplots show that the relationship between the environment of tree height and DBH is similar but not the same; there is crossover interaction in the tree height and DBH; the selected genotypes are 5, 7, 3, 4 and 9. Among them, genotype 4, 5 and 7 belong to a full sib family. The genetic material and provenance of the male parent have a visible effect on the performance of hybrid clones, and N146 is an excellent genetic material. Conclusion: 1) The tree height and DBH of Populus×euramericana in the early growth stage are highly variable in Northeast China and Central China; the growth traits of Populus×euramericana in the early growth stage are significantly affected by genotype and environment and their interaction. 2) From the information in the GGE biplots, selected genotypes are the genotype 7 with high yield and the highest stability of yield, the genotype 5 with high yield, and the genotype 4 with a yield higher than the average and a high yield stability. 3) It is suitable to grow the genotype 3 and 4 in Heishan and Zhucheng areas; it is suitable to grow genotype 5 in Ningyang and Shishou areas; it is suitable to grow genotype 7 in Luannan and Yuncheng areas.

Key words: Populus×euramericana, clones, mixed effect model, genotype by environment interaction, GGE biplot, genotype selection