Genotype by environment interaction of progeny families of Castanopsis hystrix based on leaf functional traits

To support the breeding of superior germplasm of Castanopsis hystrix, this study investigated the genetic variation patterns in leaf functional traits and genotype by environment (G×E) interactions among open-pollinated progeny families from C. hystrix seed orchards, with the aim of identifying key environmental drivers and providing a theoretical basis for precision breeding and effective deployment.

The study used thirty-three 5.5-year-old open-pollinated progeny families (with female parents from five geographical provenances) from three test sites—Yulin, Liuzhou, and Nanning in Guangxi. Leaf functional traits, including morphological and physiological characteristics, were measured. Nested ANOVA, factor analysis, and BLUP-GGE joint analysis were applied to systematically assess genetic variation patterns and G×E effects on leaf functional traits.

1) In single-environment tests, leaf functional traits exhibited significant variation at the family level, showing a pattern of “high variation among families within provenances and low differentiation between provenances.” Family heritability ranged from 0.02-0.85 for morphological traits and 0.12-0.92 for physiological traits, supporting the potential for family selection; 2) Multi-environment tests revealed significant site effects and a notable decrease in across-site heritability—0.03-0.25 for morphological and 0.10-0.14 for physiological traits—indicating a strong G×E influence on leaf development and metabolism, and its role in the coordinated improvement of growth and leaf functional traits; 3) Factor analysis identified site-specific elite families, while BLUP-GGE analysis further discerned widely adapted families with both high performance and stability. Thermal factors were identified as key environmental drivers of spatial variation in leaf functional traits.

In C. hystrix seed orchard progenies, genetic variation in leaf functional traits occurs predominantly at the family level and is significantly shaped by G×E. A family-based breeding strategy guided by G×E patterns is recommended to enhance genetic gain. Deployment of site-specific or broadly adapted genotypes according to target environments will help optimize breeding efficiency and promotion outcomes.