Eucalyptus growth under the effect of artificial defoliation

Abstract

The objective of this work was to evaluate the effects of total defoliation at planting initial stages, and along the first year of cultivation, on Eucalyptus grandis growth, from planting to plantation cut. Five treatments were tested: without defoliation; one defoliation, at 56^th day after planting (DAP); two defoliations, at 56^th and 143^rd DAP; two defoliations, at 56^th and 267^th DAP; and three defoliations, at 56^th, 143^rd and 278^th DAP. Trunk diameter at 1.30-m height and the total height of 60 trees were measured from the 21^st to the 92^nd cultivation months. The average growth of each treatment was described by nonlinear models and compared by identity tests in order to estimate the tendencies between control and the other treatments in each variable. Defoliation significantly reduces diameter of the trunk and height growth rates, and expressively decreases the income at the plantation cut. However, greater losses were verified after consecutive defoliation, along the first cultivation year. Maintaining areas that suffered severe defoliations at initial planting stages can become economically unfeasible.