Efectos del defoliador Atta cephalotes Linnaeaus. en el crecimiento y el desarrollo fisiológico e hidráulico de árboles juveniles de Gmelina arborea Roxb. en condiciones controladas

Atta cephalotes is a species of scrubbing insect that affects the development of Gmelina arborea under commercial cultivation conditions. There has been little research regarding the physiological aspects of the recovery process of the affected tree. In the present study, we analyzed the effects of the defoliation generated by A. cephalotes on the growth and the physiological and hydraulic development of juvenile trees. We used 25 trees with similar age and morphometric conditions and placed them under the same environmental conditions; 16 of them were exposed to the attack by the insect and their recovery was evaluated for 510 days assessing growth (diametric and total height), physiological (index of foliar area - IFA, transpiration, and SPAD values) and hydraulic development (turgidity, sap flow movement – SFM, and foliar moisture content-CHF). We found that the trees under attack failed to recover their growth rate with a deficiency of 39.0% in diameter and 64.3% in height. At the physiological level, they required 120 days to recover the SPAD values and 150 days to recover the stomatal conductance and the IAF at similar levels to the control. On the other hand, with the hydraulic variables, the period was shorter: leaf turgor was recovered in 45 days and the MFS and CHF in 60 days to the same values of the control. This behavior would be explained by the defoliation stress which forces the tree to restart the foliar recomposition through the movement of sugars, nutrients, and water for which the hydraulic movement is essential to avoid death due to stress.