Methods for the very early selection of Pinus radiata D. Don. for solid wood products

Abstract

• Introduction: There has been an increasing interest in very early selection of radiata pine to reduce the breeding cycle for solid wood products. For such selection, new approaches are required to assess wood quality in wood from very young stems. • Methods: Nursery seedlings of clones of radiata pine were grown in leant condition using two leaning strategies for 18-20 months. Opposite wood and compression wood were isolated from the leaning stems and tested for dynamic modulus of elasticity, density, longitudinal shrinkage, volumetric shrinkage and compression wood area using new methods evolved for testing small size samples quickly and reliably. The methods were tested for their efficiency in differentiating clones by their wood properties. • Results: Leaning of stems provided distinct opposite and compression wood for testing. Automated image analysis method used for compression wood area assessment was found to be a quick and effective method for processing large number of samples from young stems. Compression wood was characterised by high basic density, high longitudinal shrinkage and low volumetric shrinkage than that of opposite wood. Acoustic velocity in opposite wood had a strong negative association with longitudinal shrinkage. The study signifies the importance of preventing mixing of opposite wood with compression wood while assessing wood quality in young stems thus making leaning a critical strategy. The comparison of wood properties of opposite wood revealed significant differences between clones. Opposite wood of the clone with the lowest dynamic modulus of elasticity exhibited the highest longitudinal shrinkage. • Conclusion: Significant differences in measurable wood properties between clones suggest the prospects of early selection for solid wood products.