Efeito da aplicação de extratos de sementes de Crotalaria spectabilis na pré-emergência de Digitaria insularis

Abstract

In this work, possible allelopathic effects of Crotalaria spectabilis seed extracts on the germination of D. insularis seeds were evaluated. Were obtained extracts in ethanol, water and n-hexane. Ethanolic and aqueous extracts showing a high concentration of total phenols (13.9 and 13.5 mg of AG g-1 respectively) in relation to hexanic extract (1.1 mg of AG g-1). The analysis by HPLC revealed that the ethanolic extract has gallic acid, (+) catechin, vanillic acid, p-cumaric acid, resveratrol and mirecetin in their composition, while the aqueous extract showed only (+) catechin and resveratrol. The hexanic extract showed only gallic acid. No treatment with Crotalaria spectabilis seed extract caused a reduction in the germination of D. insularis, nor a reduction in the germination speed index. However, in relation to fresh and dry matter, the ethanol extract showed small differences in relation to the control. In general, the phytotoxic effects of Crotalaria spectabilis seed extracts on germination D. insularis were insignificant, not justifying the pre-emergence application and the beginning of germination.