Heritability estimates for real resin capacity and growth traits in high-gum-yielding slash pine

Key words: 
• forest tree breeding /
• Pinus elliottii /
• resin capacity /
• growth /
• heritability /
• covariance

Abstract: Resin is important industrial material，while real resin capacity（resin yielded by individual tree） was depended on both basic resin yield capacity and individual growth. There were few researches on the two factors. Real resin yields and growth traits （height，DBH，and volume） of 16 high-gum-yielding slash pine half-sib families introduced from America and a control （general families of slash pine improved for timber volume） were measured twice in two years of 2007 and 2008. Variance components estimated by SAS （V8.01 release） VARCOMP Procedure with the restricted maximum likelihood （REML） method for unbalanced individual data were used to estimate the heritability. Family mean heritability for resin production of 2007 and 2008 was 0.674 8 and 0.693 0，respectively；whereas single-tree heritability for resin yield was 0.367 8 and 0.416 2，respectively. Log volume had a family mean heritability of 0.881 0 and single-tree heritability of 0.682 6. There were highly significant（P＜0.001） correlations between tree height and DBH（R2 = 0.763 8） and the correlation between resin yields in 2007 and 2008（R2 = 0.696 9） was highly significant（P＜0.001），too. Correlations for resin yields and each growth trait （height，DBH，and volume） were significant （P＜0.05）. The analysis of variance revealed that family effects of growth traits and resin yields were all significant （P＜0.05），which means the selection of high-gum-yielding and high-volume-harvesting family was effective，thus four families with high gum and volume were selected according to Duncans contrast. This study showed that basic resin yield capacity and amount of growth were both the important factors for selection of high-gum-yielding slash pines，and the two factors have significant correlation and high heritability.［Ch，8 tab. 14 ref.］