Potencial alelopático de extratos do cumarú (Amburana cearensis A.C. Smith) e da jurema-preta (Mimosa tenuiflora (Willd.) Poir) na germinação e crescimento de sorgo (Sorghum bicolor L.), milho (Zea mays L.) e feijão guandu (Cajanus cajan L.).

Abstract

Studies of allelopathic effects in plants are of great interest in the establishment and management of agrosilvipastoral systems. The present study consisted of two laboratory bioassays and a greenhouse experiment. The first bioassay studied the effects of increasing concentrations (0, 25, 50, 75 and 100%) of the aqueous extract of cumarú (Amburana cearensis A.C. Smith) bark and leaves on sorghum (Sorghum bicolor L.), corn (Zea mays L.), and guandu bean (Cajanus cajan L.) seed germination. The second bioasssay studied the effects of the aqueous extract of jurema preta (Mimosa tenuiflora (Willd.) Poiret) bark and leaves on sorghum and guandu bean seed germination and seedling development. The greenhouse experiment studied sorghum seed germination and seedling development in soil substrate moistened with five levels (0, 25, 50, 75 and 100%) of water extract of cumaru bark or leaves. Sorghum, corn and guandu bean seed germination and plantule growth in the first bioassay were reduced with the increase of the concentrations of bark or leaf extracts. In the second, only the jurema preta leaf extract reduced seed germination and plantule growth. In the greenhouse experiment, the growing concentrations of cumarú extracts did not affect germination and growth. The two native species of the caatinga forest show allelopathic effects, and may regulate plant succession in the caatinga ecosystem. Thus, further studies on these species should be considered.