Genetic Parameter Estimates and Genotype × Environment Interactions of Growth and Quality Traits for Betula alnoides Buch.-Ham. ex D. Don in Four Provenance-family Trials in Southern China

Abstract

Betula alnoides is a valuable timber species with wide ecological adaptability in Southeast Asia and southern China. There are more than 150,000 ha of B. alnoides plantations in China until now. However, heavy differentiation in growth and quality traits with low productivity are usually seen in the practice. Elite germplasm are thus urgently needed for this species. Here growth and quality traits for 199 families of 25 provenances were assessed at four sites when 10–15 years old to estimate genetic parameters and reveal genotype by environment (G × E) interaction, and screen out superior provenances and families for plantation forestry of B. alnoides. The growth and quality performances of provenances varied with sites. Significant site, provenance, family and provenance-site effects were revealed for most growth and quality traits, while significant family-site effects were only observed in crown width (CW) and crown shape (CS), inferring that there existed significant G × E interaction. The provenance repeatability ( h p 2 ) and family heritability ( h f 2 ) of all tested traits ranged from 0.026 to 0.636 and 0.148 to 0.578, respectively. Stem volume showed the highest genetic and phenotypic coefficients of variation (GCV, PCV) among all traits at each site. The diameter at breast height (DBH), tree height (H), height to live crown base (HCB) and CW were strongly correlated with other traits, and were also under relatively higher genetic control and had stronger discriminating ability on genotype differences. Through biplot analyses of main genotypic effect and G × E interaction (GGE) for these traits, five provenances and 20 families were screened out with selection ratio of 20 % and 10% at provenance and family level, respectively. The genetic and realized gains at provenance level ranged from 0.25% to 2.01% and 2.43% to 14.84%, and those at family level ranged from 0.85% to 21.22% and 5.76% to 36.71%, respectively. The findings lay a foundation for subsequent study on genetic improvement and breeding of this species, and application of the superior provenances and families will greatly increase the productivity of its plantations in practice.