O vigor da planta altera a densidade de galhas em populações de Baccharis longiattenuata (Asteraceae) sob distintas condições de solo?

Abstract

The plant vigor hypothesis suggests that more vigorous plants support higher density of galls. This study will evaluate such hypothesis using a mite-Baccharis longiattenuata system in two restinga populations under different environmental conditions. The measures of vigor are: height and stem diameter, volume and crown area, number of leaves per branch, nitrogen content and specific leaf area. The results evidenced the vigor effect on the density of galls. In addition to plant vigor, other factors may have indirectly influenced the observed pattern. In shrub-tree restinga, the highest water intake may have influenced the growth rates and formation of meristematic sites, which changes the gall-host dynamics. Different than expected in the literature, a population with less sclerophyllous leaves presented higher density of galls. On the other hand, in shrub restinga, the lowest SLA values, in response to high light incidence and lower soil water availability, may be influenced by higher density of mites per gall, since more sclerophyllous leaves have greater longevity, favoring in the time of permanence of the mature female inside the gall, increasing the density of mites per gall in this environment. A discussion is presented of environmental conditions that conform to the gall distribution pattern found.