Developmental rates and morphological properties of fibres in two eucalypt clones at sites differing in water availability

Abstract

One of the ways in which the global forestry industry can remain competitive is to improve the predictability of properties of fibres produced, particularly in plantations. Since the properties of the fibres are determined by growth and developmental processes, it is of importance to understand these processes and how they are affected by changing environmental conditions. Using two Eucalyptus spp. clones growing at sites contrasting in available water, this study measured the rates of fibre production, fibre transverse radial enlargement and fibre secondary thickening and the duration of the cell cycle, as well as the duration for which the processes of fibre enlargement and wall thickening continued. Samples were taken from the cambial zone in late summer (February–March) and in winter(May–June). The study found that season had the greatest effects on characteristics of the developmental zones as well as on developmental rates and durations, although there were significant effects of both site and clone. This was complicated by significant interactions that occur between genotype, sitetype and short-term variations in environmental conditions. It was found, however, that dry sites, where trees are experiencing comparatively high levels of environmental stress, can be expected to experience greater extremes in developmental processes between seasons, or over relatively short periods, generally, than wetter sites. These sorts of fluctuations will also translate into greater wood quality variation, and hence different site-types should be managed accordingly. Results from this work will contribute to the development of models of xylogenesis which are currently in development.

Southern Hemisphere Forestry Journal 2007, 69(2): 71–79