Identification and Characterization of Tension Wood in Acacia auriculiformis A. Cunn. ex Benth. and Acacia mangium Willd. Grown in Kerala

Abstract

The present study was carried out to characterize the tension wood and normal wood in Acacia auriculiformis and Acacia mangium and to analyse their variation in fibre and vessel morphology. The fibre morphological characters included fibre length and diameter, fibre lumen diameter and fibre wall thickness, and those of vessels included vessel diameter and frequency. Wood blocks of 1 cm3 were obtained from the base billets of felled Acacia trees, and microtome sections were prepared. In order to distinguish tension wood and normal wood, sections were stained using toluidine blue-‘O’. In order to obtain fibre dimensions, the maceration was carried out with Jeffry’s fluid. The results revealed that the anatomical properties, viz., fibre morphology and vessel morphology, were found to vary between tension wood and normal wood. The fibre morphology of both the species followed the similar pattern in which magnitude of all the fibre properties was higher in tension wood than in normal wood. Vessel morphology of both the species followed the similar trend; however, frequency and diameter of the vessels were much lesser in tension wood than in normal wood. The present study distinctly proved the occurrence of tension wood in Acacia auriculiformis and Acacia mangium. In order to reduce the occurrence of tension wood or to prevent its occurrence, better silvicultural and management practices could be adopted, such as closer spacing, and early and proper pruning.