Pattern of genotype by environment interaction for radiata pine in southern Australia

Milos IVKOVIC, Washington GAPARE, Huixiao YANG, Gregory DUTKOWSKI, Peter BUXTON, Harry WU

Key message: Based on analyses using 20 genetically connected radiata pine trials and on the pattern of trial-trial genetic correlations, current regionalisation of breeding in southern Australia seems justified. However, relationships between environmental variables and genotype by environment interaction are complex.

Current radiata pine breeding and deployment in Australia is based largely on the plantation inventory zones rather than on biological patterns of genotype by environment interaction (G × E), and consequently cannot deliver optimal genetic gains across the whole plantation estate. This study examined patterns of G × E to facilitate deployment of genetic stock to particular environments. We used 20 genetically well-connected trials across southern Australia to obtain estimates of genetic correlations between performances at different trial sites. Extended factor analyses (XFA) were used to estimate G × E variance and produce a matrix of site-site genetic correlations. The patterns among these correlations were examined using a heat map and hierarchical clustering. The XFA captured a large proportion of both additive and non-additive G × E. Significant G × E for diameter growth can be expected between Tasmania and Mainland, and within Tasmania itself. The study also confirmed presence of G × E between Murray Valley region in New South Wales and the rest of southern Australia. The G × E interaction at transcontinental scale can be correlated to the climate variables, primarily rainfall and temperature; however, the drivers of G × E may also be related to smaller scale environmental variation (i.e. soil and terrain variation).

Link to the full paper.