Allelopathic suppression of Sorghum bicolor (L.) moench shoot extracts on weed germination and on weeds treated by foliar application

This study aims to determine the contents of phenolic compounds from sorghum shoot extracts by fractional extraction in different solvents (ethanol, ethanol-chloroform, ethanol-hexane, ethanol-ethyl acetate, and ethanol-methylene chloride) and to assess their weed control efficacy. Results showed that the highest total amount of phenolic compounds was extracted using the solvent 'ethanol-ethyl acetate'. In order to assess allelopathy activity for potential weed management purposes, a bioassay was performed with four weed species including Abutilon avicennae, Digitaria sanguinalis, Amaranthus retrqflexu, and Echinochloa crus-galli. A germination study indicated that all sorghum extracts had an inhibitory effect on all four-weed species. Bioassay results showed that, the extract obtained by ethanol-ethyl acetate solvent was more effective than other extracts (ethanol, ethanol-chloroform, ethanol-hexane, and ethanol-methylene chloride). In this work, the identification of the best extraction method from sorghum using different solvents could possibly lead to the development of an environmentally friendly natural herbicide for a more sustainable agriculture.