Fitotoxicidade e citotoxicidade de extratos de Schinus molle L. (Anacardiaceae) em Lactuca sativa L.

Abstract

Schinus molle L. is a plant belonging to the family Anacardiaceae that presents many popular uses, among which the medical, landscape and timber purposes. Their metabolites, at an environmental context, can interact with plants and other organisms in the ecosystem through the effect known as allelopathy. This interaction can be assessed by several parameters, mainly the germination of neighboring plants. In this context, the aim of this study was to evaluate the allelopathic effect of different organs of S. molle L., as well as the behavior of this effect in populations under different environmental and management pressures, in bioassays with lettuce (Lactuca sativa L.). The first work consisted in to evaluate the behavior of lseeds of letucce exposed to water and ethanol extracts of different plant structures that were collected from a population of Alfenas. The second part of the work was to evaluate the interference effect of pruning on allelopathy. For it, leaves were collected in two distinct populations, one with pruning and one without regular pruning. To evaluate the allelopathic effect of S. molle, germination, number of normal seedlings, germination velocity index, root elongation, fresh weight, dry weight, mitotic index and chromosomal abnormalities were evaluated. The experimental design was a completely randomized block design with three replications and five concentrations in the first experiment. In the second experiment were evaluated only four concentrations. Statistical analysis consisted of analysis of variance - ANOVA (p<0.05), when possible was adjusted linear regression model, and for the other results means were compared by Scott-Knott test. The results obtained in the first experiment for both, aqueous and ethanol extract, showed differences between plant organs tested, with lower interference obtained when lettuce was exposed to extracts of ripe fruit and the greatest interference when exposed to extracts of green fruits. In all cases it was observed that with increasing concentration there is a decrease of the measured parameter, showed concentration dependent effect. In the second experiment concentration-dependent effect was also observed in the parameters tested except for fresh biomass exposed to ethanol extract, regardless of population. All variables showed the allelopathic effect of species.