Genetic parameters of Fagus sylvatica L. open-pollinated progeny trials in a gradient of site fertility and climatic conditions

MOHYTYCH, VASYL ; NIEMCZYK, MARZENA; CAPPA, EDUARDO PABLO; KLISZ, MARCIN; KOWALCZYK, JAN

Vernon

Conferencia; Forest Genetics 2023: Discovery & Innovation in Changing Climates; 2023

The Western Forest Genetics Association (WFGA) and the Canadian Forest Genetics Association/ l?Association canadienne de génétique forestière (CFGA)

Fagus sylvatica (FS) is a broadleaved tree species of high economic importance in European forests. Despite previous studies indicating high intra-population variability, individual selection is rarely used in this species. We aimed at analysing genetic parameters for growth traits (diameter and tree height) of open-pollinated (OP) progeny of FS, while accounting for site fertility and climatic conditions. We studied three series (each consisting of four experimental sites) of 10-year-old OP progeny trials in north-western Poland, with a total of 189 families and 74,374 seedlings planted across a gradient of site fertility and climatic conditions. To account for environmental heterogeneity within sites, we tested models using three approaches: a priori block design, and a posteriori B-spline and autoregressive residuals. Heritability and genetic correlation were estimated using a multi-trait-multi-site model. Phenotypic values for progeny growth traits and their genetic parameters were analysed in relation to the site fertility and climatic transfer of the tested material. Our results showed considerable spatial variability that affected the estimated genetic parameters within each site. Notably, models using a B-spline and an autoregressive approach produced more accurate estimates of genetic parameters than models using an a priori block design. Single-site narrow-sense heritability for growth traits ranged from 0.03 to 0.24 and varied most among fertile sites. Genetic correlations between sites (0.20-0.81 for diameter and 0.34-0.81 for tree height) revealed significant effects of genotype-by-environment interaction in each series tested. Specifically, on less fertile sites, the heritability of growth traits was more constrained by site fertility than by climate. In contrast, progeny on fertile sites exhibited higher heritability but also a local adaptation pattern to precipitation, with climate transfer significantly affecting heritability and tree performance. Therefore, our findings emphasize the importance of considering both site fertility and precipitation transfer to increase the genetic gain from individual selection of FS.