Clonal Variation In The Quality of Radiata Pine Random Width Boards

Robert Beauregard, Rado Gazo, Mark O. Kimberley, John Turner, Scott Mitchell, Anthony Shelbourne

Abstract


This clonal study was undertaken to analyze clonal variation in the quality of random width boards, and to document broad sense heritabilities of the board quality and the associated tree variables in radiata pine (Pinus radiata D. Don). Two individual trees from each often clones were selected based on a wide range of clone mean values for diameter at breast height (DBH), internode index, branch index, and outerwood basic density.

Several defect types and frequencies showed differences between clones; variation between clones was greater for defect frequencies than for defect areas. Also differences between clones were greater for boards from unpruned logs than from pruned logs. Knot frequency was far higher in boards coming from the clones with shorter internodes, while knot area per m2 did not vary significantly between clones. Internode length appeared to be highly heritable. The blemish area per m2 from pruned logs was highly variable between clones. Causes and exact configuration of this latter defect are largely unknown and unpredictable but appear to be associated with pruning.

Differences were observed in the grade distributions between clones. For all log types, the best performing clone was a large DBH clone with the longest internodes, while a small DBH clone with the shortest internode was the worst. These results show that defect frequency and grades in appearance lumber and associated tree characteristics show high broad sense heritability. This suggests that the grades and the value of these products can be predicted, particularly from tree internode index. A breeding program for long internode radiata pine, started in 1970, has already shown that this trait responds well to selection and breeding.


Keywords


Pinus radiata;clones;defect frequency;DBH;internode;random width boards

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