TERPENE VARIABILITY OF MAINLAND PINUS-RADIATA

Abstract-Wood and foliage mono- and sesquiterpenes of 45 Pinus radiata trees from the three native mainland populations in California were analysed using conventional and chiral gas chromatography. The wood was found to contain no detectable sesquiterpenes. Wood monoterpenes mainly consisted of beta-pinene [98.5% (-), 1.5% (+)] and variable ratios of (-) and (+)alpha-pinene, the (-) enantiomer predominating in the southernmost population; twenty other monoterpenes were detected. The main foliage monoterpenes were (-)alpha- and (-)beta-pinene, (-)limonene and (-)beta-phellandrene. (-)alpha-Pinene increased from north to south, while (-)beta-phellandrene and especially (-)limonene decreased. The predominant foliage sesquiterpenes were caryophyllene, germacrene D, bicyclogermacrene and 4-alpha-hydroxygermacra-1(10),5-diene (4-alpha-HGD); twenty-four other sesquiterpenes were detected. The central (Monterey) population was distinguished by higher amounts of germacrene D and decreased levels of caryophyllene, bicyclogermacrene and 4-alpha-HGD. Canonical discriminant analysis of each data set (foliage monoterpenes, sesquiterpenes and wood monoterpenes) for all trees showed good separation among the populations with about 95% of the trees correctly grouped. When the three data sets were combined, the populations were completely separated and all trees were correctly grouped. The Mahalanobis distance between the southern pair (Monterey/Cambria) was less than between the northern pair (Ano Nuevo/Monterey).