Abstract:
Objective Through multi-location trials of birch progeny, this paper analyzes their fast-growth and stability, selects excellent genotypes, and provides a scientific basis for the renovation and reconstruction of seed orchard.
Method The study focused on the progeny test forest of 8-year-old half-sibling families of birch at three experimental sites. Traits such as tree height, diameter at breast height, wood volume, straightness, and survival rate were investigated. The ASReml-R4.0 software package in the R language was employed to fit a mixed linear model with heterogeneous variance. Breeding values for each family at different trial locations were obtained through best linear unbiased prediction (BLUP). Additionally, a comprehensive evaluation and selection of trial sites and families were conducted using the GGE biplot method.
Result (1) In the mixed linear model analysis with location as a fixed effect, differences in the offspring of half-sib family lines of birch reached significant levels (P < 0.05, Z ratio > 1.5) for all five traits among locations, among family lines, and among location × family line interactions. (2) Based on BLUP values of each trait, the GGE biplot revealed that Shangzhi trial site had the optimal discrimination and representativeness. Qing’an and Shangzhi trial sites showed the strongest correlation, while Yongji was almost uncorrelated with Shangzhi and negatively correlated with Qing’an. (3) Progeny from birch family 16 and 15 exhibited the best fast-growth characteristics, and families 4 and 32 demonstrated the highest stability. Considering a comprehensive ranking based on stability and fast-growth characteristics of each family, four excellent families, including family 16, 40, 15, and 38, were selected with a 20% inclusion rate.
Conclusion There are significant differences in the growth performance of birch half-sibling families at different trial locations, and growth performance also varies among different families within the same trial location. The interaction between genotype (family) and environment (site) significantly influences the growth of birch. Based on the comprehensive traits of stability and fast-growth for each family, families 16, 40, 15, and 38 have been selected as excellent half-sibling families of birch.
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