Analysis of Phenotypic Plasticity and Growth Strategies of Multi-Generational Selected Cunninghamia lanceolata Varieties in Different Artificial Forest Soils

Aims: Maximizing tree growth potential and effectively integrating with the growth environment are vital strategies for enhancing phenotypic plasticity. These approaches enable tree species to adapt to dynamic environmental conditions by leveraging the effects of the environment, genotype, and genotype-by-environment (G×E) interactions. Methods: In this study, 25 improved Cunninghamia lanceolata varieties, developed through multiple generations of breeding, were transplanted into four artificial forest soils. We analyzed genotype, environment, and G×E interactions contributing to variations in growth, biomass, and root traits, identifying key factors driving phenotypic plasticity. Results: The results show that soil environmental effects and G×E interactions are the dominant factors influencing trait variation, explaining 55.89% to 93.94% of the observed variation, while the varietal effect is relatively minor. Pronounced phenotypic plasticity drives divergent selection in aboveground and belowground growth strategies. Root average diameter (RAD), total root volume (TRV), and root-to-shoot ratio (R/S) are critical traits influencing root dry weight (RDW). Although RDW does not directly impact plant height, it significantly affects aboveground dry weight (ADW). Conclusions: The above results emphasize that the changes in the aboveground-belowground growth strategies of Chinese fir during the seedling stage are related to the plasticity of root functional traits. For multi-generational genetically improved varieties, we explored how leveraging genetic effects (G), environmental effects (E), and genotype-by-environment interactions (G×E) in the selection of aboveground growth and root functional traits influences the driving processes of biomass accumulation. Our results provide actionable insights for selecting soil-specific genotypes in subtropical plantations, reducing dependency on chemical fertilizers.