Phytotoxic potential of Sesbania virgata seeds on germination and early growth of seedlings Leucaena leucocephala (Lam.)de Wit

Abstract

The use of invasive plants to recover degraded areas has been extensive, but at the same time, worrying, because the rapid colonization of these species is becoming a threat to native biodiversity. Sesbania virgata (sesbania) is a legume species, native to South America, pioneer, flood tolerant and with rapid growth, being described as invasive in several regions. Studies conducted by our group revealed that seeds of sesbania exude antifungal and phytotoxic secondary metabolites at the beginning of the imbibition and the flavonoid (+)-catechin is the main phytotoxin found in these exudates. The exudates from sesbania seeds inhibited germination and initial growth of agronomic species, as well as delay the mobilisation of their storage carbohydrates. In two forest species that co-occur with sesbania, these effects were much less intense. A recent hypothesis to explain the success of invaders species suggests that more intense phytotoxic effects are expected between plants that do not have common evolutionary histories. Thereby, we aim to evaluate the phytotoxic effects of the exudates of sesbania seeds on seed germination and the metabolism of an exotic species, Leucaena leucocephala (leucena) to test the hypothesis that the effects of allelochemicals are more intense between species that do not have common evolutionary histories. Additionally, we intend to investigate the contribution of the abscisic acid, that is known to be exuded by sesbania seeds, in its allelopathic effect as well as investigate the possible exudation of phytotoxins by leucena seeds. This study proposal represents the continuation of previous studies supported by FAPESP (grants and fellowships) and its proposition aims to answer some crucial questions arising from these studies. Therefore, we intend to contribute to the understanding of plant-plant interactions and ecophysiological processes involved in the adaptive advantages that some species present during their initial establishment.