Avaliação dafitotoxidez de 18 espécies ocorrentes na restinga de Massambaba, Rio de Janeiro

Abstract

The Environmental Protection Area of Massambaba concentrates diverse vegetation formations with a great floristic richness and endemism. Unfortunately this area is subject to both human action that some fragments are degraded. To recover this vegetation is ecologically important to understand the mechanisms of ecological succession. As little is known about interactions between plants sandbank, and even less from the perspective of allelopathy (a plant exerts influence on other agencies to release secondary metabolites to their surroundings), we aimed to the realization of biological assays with native species. Initially we determined the optimum conditions for extraction of metabolites, and finally were tested 18 native species (Allagoptera Arenaria, Andira legalis, Byrsonima sericea, Clusia fluminensis, Couepia ovalifolia, Erythroxylum ovalifolium, Eugenia copacabanensis, Eugenia selloi, Garcinia brasiliensis, Guapira opposita, Maytenus obtusifolia, Myrsine parvifolia, Neomitranthes obscura, Ocotea notata, Pouteria caimito, Renvoizea trinii, Vitex megapotamica and Tocoyena bullata). We applied the extracts and checked the germination and early growth of lettuce seeds. For this, leaves of these species were collected seasonally in non-flooded open shrub and in sandbank formation Massambaba for preparing aqueous extracts. Extracts were obtained by drying the leaves at 60°C for further soaking, heating, dilution and filtration to give concentrations of 5 and 10% concentration (weight/volume). Parameters to evaluate the phytotoxicity were: the percentage and speed of germination and root length after seven days of growth in Petri dishes moistened with extracts. In addition to these three parameters, the index of global effect, which transforms the three variables into a single index and a cluster analysis (Euclidean distance, Ward method) to classify them according to the index value was used. The growth inhibition was observed in all species, and there was significant seasonal differences, especially in winter. This suggests that the differences between levels of toxicity symptoms are correlated to the environment and genetics. If the inhibitory action of species with greater allelopathic effect is proven, new strategies can be developed for release in environmental conservation projects