Genetics of heartwood formation and moisture status in Pinus radiata

Genetic parameters of heartwood formation (Hf), detected using o-anisidine/ sodium nitrite, and moisture status (average content and content gradient) of a small 4 by 4 diallel progeny test of radiata pine involving parent 800 55 were studied. Both properties exhibited a large phenotypic variation wit hin families at 23 years of age. Parent 80055 developed heartwood to a grea ter extent than other parents (12038, 12197 and 12447), especially 12197. 8 0055 progeny were drier in the inner corewood (initial 6 growth rings) than progeny of other parents. This implies that wood of 80055 progeny may be m ore brittle during refining than that of other progeny. Strong positive phenotypic and genetic correlations were found between grow th traits (section area at breast height, height, sapwood area, initial fiv e year radial growth), Hf (rings and area) and moisture content gradient (M cg) between the inner corewood and outer slabwood. Genetic control of heart wood formation traits was primarily through additive action of genes (GCA). Specific combining ability (SCA), reciprocal and maternal effects were abs ent, possibly due to the small sample size and a small number of reciprocal pairs. Additive genetic variance accounted for a third of total phenotypic variance in heartwood formation. The heritabilities of Hf and Meg were hig h suggesting selection for traits was likely to be very effective.