Propriedades da madeira como potenciais biomarcadores de tolerância a distúrbios fisiológicos: comparação de genótipos de eucalipto divergentes

Eucalypt Physiological disorder (PD) is characterized by symptoms such as bark cracking, loss of apical dominance, adventitious shoot emission, leaf abscission, among others. The use of wood biomarkers easily measurable can contribute as a criterion for the selection of tolerant clones. The objective of this study was to evaluate the wood and bark properties of commercial Eucalyptus clones tolerant and susceptible to the PD and to identify profiles of wood and bark responses related to the disorder. Three trees per clone were sampled at 3 positions along the trunk: DBH (diameter at breast height), 50 and 75%. The wood properties evaluated were wood and bark density, heartwood, sapwood and bark percentages, and wood chemical composition (extractives, lignin, syringyl/guaiacil, holocellulose, and ash). Although there were different values of bark density between the clones and their PD susceptibility classification, the averages were statistically similar. Despite the difference of wood density and extractive content, there were no trends in relation to clone susceptibility or phenotype tolerance. In general, tolerant clones showed higher growth, aboveground biomass, heartwood percentage and syringyl/guaiacil ratio, and lower bark content. These characteristics are indicated as potential biomarkers related to physiological disorder tolerance.