WOOD DENSITY AND MICROFIBRIL ANGLE IN 10 PINUS RADIATA CLONES: DISTRIBUTION AND INFLUENCE ON PRODUCT PERFORMANCE

A 27-year-old Pinus radiata D. Don clonal trial (with clones propagated from 7-year-old seedlings) was screened to identify clones with a wide range of branch size, internode length, and mature wood density (outer five rings at breast height). Four trees (ramets) from each of 10 such clones were subsequently chosen for use in wood processing/product performance studies, and wood properties were measured on discs taken from each end of 5-m logs up to the merchantable limit (200-mm small-end diameter). Properties assessed included wood density, microfibril angle, spiral grain, and incidence of compression wood. Wood density values differed markedly between clones, but within each the overall patterns of density variation were consistent from pith to bark and between stem levels, indicating high heritability. Broad-sense heritability estimates were 0.6 and higher for wood properties, except compression wood (0.43) and knot area ratio (0.38). Over all wood samples, there was strong evidence for heritability of density and spiral grain, good evidence for heritability of microfibril angle, and wea