High heritability of wood extractives in Pinus sylvestris progeny tests

Pinosylvin, resin acid, fatty acid, and sterol contents were analyzed in no rth Swedish Scots pine (Pinus sylvestris L.) heartwood from 160 and 44 tree s in two full-sib progeny tests, aged 25 and 44 years, respectively. Large variations were found between individual trees, with coefficients of variat ion of ca. 0.7, 0.8, 0.3, and 0.5 for the four groups of extractives, respe ctively. Heritabilities were estimated to be 0.5-0.7, ca. 0.6, 0.3-0.8, and 0.6-0.9, respectively, and corresponding genetic coefficients of variation were 0.4-0.8, ca. 0.6, ca. 0.2, and 0.2-0.5, respectively. The results ind icate that there is strong genetic control of the wide individual variation , which consequently provides excellent opportunities for genetic improveme nt. Although similarities in genetic parameters were observed at the two te st sites, some differences in total levels of the extractive groups and in their isomeric ratios were detected. This suggests that the genetic control of these features, although strong, may be modulated by environmental fact ors or other influences, such as the phase of tree development.