Genetic parameter estimates for radiata pine in New Zealand and New South Wales: A synthesis of results

This paper summarises genetic parameters for radiata pine, based on 1961 fi rst-generation selections: 1660 tested in New Zealand and 301 tested in New South Wales. Three genetic parameters were estimated from analyses of pair s of sites: narrow-sense heritability (h(A)(2)), type B genetic correlation (r(B)), and the genetic correlation between different traits (r(G)). Withi n-site estimates of narrow-sense heritability (h(w)(2)) were also obtained. The traits were height, over-bark diameter at breast height (dbh), stem st raightness score, branch cluster frequency score, malformation score, needl e retention score, crop acceptability, wood density and grain spirality. Th e trees were assessed at between 5 1/2 and 11 years from planting, with mos t of the trials assessed near age eight. Over 154,000 trees were assessed f or growth and form, 6,200 for grain spirality and 6,700 for wood density. A total of 172 estimates of h(A)(2) and r(B) were obtained; these were uneq ually distributed across traits, from six estimates for spiral grain to 33 estimates each for dbh, branching and straightness. The mean h(w)(2) were h igher than the pair-wise estimates; the discrepancy was greatest for height , malformation and needle retention score. The highest mean h(2), obtained by both approaches, was for branch cluster frequency. The overall mean h(A) (2) were: 0.11 (dbh), 0.13 (height), 0.19 (straightness score), 0.33 (branc h cluster frequency score), 0.12 (needle retention score), 0.06 (acceptabil ity) and 0.26 (spiral grain angle). The highest average r(B) were for strai ghtness, branch cluster frequency and spiral grain angle (0.89, 0.87 and 0. 81 respectively). Based on 120 progenies on two sites, an h(A)(2) of 0.72 a nd a r(B) of 0.99 were obtained for wood density. A total of 711 r(G) estimates were obtained, ranging for three estimates fo r spiral grain- acceptability to 66 estimates each for dbh-straightness and branching-straightness. Branch cluster frequency was positively correlated with height, dbh and straightness. Acceptability was strongly and positive ly correlated with straightness and malformation score. There appeared to b e weak unfavourable correlations between dbh and grain spirality, and betwe en dbh and density (the latter estimate based on two sites only).