Adaptability and stability of eucalypt clones at different ages across environmental gradients in Brazil

Abstract

The genetic gains from eucalypt breeding programs have decreased compared to previous decades while productivity reduced in recent years. This decrease is mainly attributed to climate change that, according to studies, has been limiting productivity and changing the adaptation of forest species. But other aspects can be listed, as pests and diseases and decreasing gains with the advance of breeding programs. The objective of this work is to investigate the genotype × site × age interaction in a multi-environment trial with eucalypt clones to verify the adaptability and stability of the genotypes and, finally, to identify mega-environments over time, as well as the influence of climate variables on the genotype performances. The trait diameter at breast height (DBH) of 11 Eucalyptus commercial clones at 11 sites (range from −0.84 to −24.23 latitude and from −39.60 to −52.59 longitude) and three evaluated ages (Age 1 – ranging from 13 to 17 months after planting; Age 2 – from 31 to 34 months; Age 3 – from 48 to 53 months old) was measured and analyzed by factor analytic multiplicative mixed (FAMM) model associated with the GGE biplot and multivariate regression tree using climate variables. A significant G × E interaction and genotypes with different performance across environments and ages were observed. There are clones with high adaptability to specific sites while others show good stability. The results clustered the sites into three mega-environments according to a latitude gradient, over time. The performance of Eucalyptus clones over time indicate precisely either roughly similar or extremely contrasting environments. Temperature affected the most the clustering of the studied sites followed by the latitudinal gradient, impacting productivity negatively, regardless of age. These results may help future studies on the development of selection strategies in tropical regions to address climate change and assist forest breeding programs to deal with the effect of climate change on eucalypt productivity.