Alelopathic effect of aqueous extracts of leucena (Leucaena leucocephala Wit) leave and fruit on germination and root growth of canafistula (Peltophorum dubium Spreng)

Abstract

Nowadays exotic plants represent a big threat to biodiversity because when they are present in favorable environments, they can influence the development of native plants, as well as they can change the natural functions of the environment. Wrong management practices are some of the main factors that support the environment invasions by exotic species. Leucena (Leucaena leucocephala Wit.) is an exotic species that takes part in Itaipu Dam recuperation riparian areas. Exotic species may have allelopathic effects. The objective of this study has been to verify allelopathic effects of aqueous extracts of leucena leaves and fruits upon germination and root growth of canafistula (Peltophorum dubium Spreng.), a native species. Twelve treatments with four replications have been used, divided in two stages, six treatments each. The utilized treatments were: water, 20%, 40%, 60%, 80% and 100% extract. All the seeds were scared mechanically. The germinated seeds have been counted daily. The length of the roots has been evaluated at the third and seventh day of experiment. The fruit extract presented more allelopathic effects than the leaves extract. The roots were sensitive both to the fruits and leaves extract.