Compression Wood does not Form in the Roots of Pinus Radiata

Abstract

We investigated the potential for the roots of Pinus radiata D. Don to form compression wood. Compression wood was not observed in either the tap or any lateral roots further than 300 mm from the base of the stem. This suggests that either the roots do not experience the stresses required to induce compression wood formation, or that they lack the ability to form it. Roots artificially subjected to mechanical stress also failed to develop compression wood. It is therefore unlikely that an absence of a compressive load on buried roots can account for the lack of compression wood. Application of auxin to the cambia of lateral roots was similarly ineffective at inducing the formation of compression wood. These observations suggest that the buried roots of radiata pine lack the ability to develop compression wood. We also report the formation of an atypical S3 wall layer in the mechanically-stressed and auxin-treated tracheids and suggest that a reaction wood that is different to compression wood may well form in roots.