Allelopathic potential of species of Pteridaceae (Pteridophyta).

Ferns exhibit a strong pattern of dominance in the areas in which they grow, forming almost pure associations, where only a few species coexist. Ethanol extractions of five species of Pteridaceae, in concentrations of 250, 500 and 1000 mgllitre, were evaluated using germination and growth bioassays under laboratory conditions, to verify the potential for allelopathic activity against lettuce cv. Grand rapids and onion cv. Baia periforme. Adiantopsis radiata, Adiantum serratodentatum and Pteris denticulata var. denticulata were collected in Dourados, Mato Grosso do SuI, Brazil, while the Adiantum tetraphyllum and Pityrogramma calomelanos var. calomelanos were collected in Ponta Pora. The bioassays revealed the following: (1) the five vegetal extracts did not significantly interfere with the germination of lettuce or onion; (2) the extracts of Adiantum serratodentatum, Adiantum tetraphyllum, Adiantopsis radiata and Pityrogramma calomelanos inhibited the radicular growth of lettuce seedlings; (3) Adiantum serratodentatum, Adiantum tetraphyllum and Pteris denticulata inhibited the growth oflettuce hypocotyls; (4) Adiantopsis radiata, Adiantum serratodentatum and Pteris denticulata inhibited both the growth of the radicles and the coleoptiles of onion seedlings.