Deformação residual longitudinal (DRL) e tangencial (DRT) em seis clones de Eucalyptus spp.

Abstract

The species of Eucalyptus genus present high levels of growth stress. These stresses are mechanical efforts generated during the tree growth to help maintaining the balance of the cup, in response to environmental (light, wind and inclination of the land) and silvicultural agents (pruning, thinning and planting density). The growth stresses are responsible for the cracks of tops, in logs and boards, and for the warp after the breaking down. This research evaluated the level of growth stress, measured by the longitudinal residual and tangential strain (DRL and DRT), around the circumference of the trunks of alive trees of six clones of Eucalyptus spp., at the age of 10.5 years, and verified the effect of the planting parcel. The clones belong to VMM-AGRO, and they are coming from a clonal test area implanted in the Bom Sucesso farm, located in Vazante-MG. For evaluating the experiment, the model adopted was the completely randomized one disposed in factorial outline with two factors (clone and portion) in three repetitions. The results indicated that the average LRS was 0.093 mm and that the average LRT was 0.025 mm. It was verified that, for LRS, the clone effects and planting parcel were significant, while the interaction effect was not significant. For LRT the parcel and interaction effect were significant, while clone effect was not significant. Clones 44, 58 and 47 presented the smallest levels and better distributions of LRS, while, the clones 27, 44 and 58 presented the highest LRS levels. The clones 44 and 58 presented the best distribution and the smallest level of growth stress and may be considered potentially apt for producing sawn wood or solid wood.