Genotypic Variation and Genotype-by-Environment Interactions in Growth and Wood Properties in a Cloned Eucalyptus urophylla x E. tereticornis Family in Southern China

Using a cloned Eucalyptus urophylla × E. tereticornis family, the present study estimated clonal mean repeatability, inter-trait correlation, and clone-by-site interactions for height (H) and diameter at breast height (D) across 0.5-8 years of age as well as 8-year-old wood basic density (BD8), cellulose content (CC8), hemi-cellulose content (HC8), Klason lignin content (LC8), and lignin syringyl-to-guaiacyl ratio (S/G8). Clonal mean repeatability estimates were 0.40-0.91 for growth traits H and D over 0.5-8 years and 0.50-0.87 for wood properties at age 8 for three separate sites (except that of 0.01 for HC8 at Yanxi) and across sites, indicating moderate to high levels of genetic control of the traits investigated. H had high positive genetic correlation with D. Growth traits (H and/or D) showed generally positive genetic correlation with BD8 and CC8 while negative with HC8 and LC8. Significant genotype-by-environment (clone-by-site) interactions were observed for most traits, suggesting that clones should be matched to sites to increase genetic gain. Our results suggest that there is potential to use E. urophylla × E. tereticornis clones to increase yield with desirable wood properties in Southern China.