Allelopathic Activity of Hairy Beggarticks (Bidens pilosa L.) Extracts on Germination and Seedling Growth of Weedy Rice (Oryza sativa f. spontanea Roshev.) and Creeping Sensitive Plant (Mimosa diplotricha C.Wright ex Sauvalle)

Abstract

            In this study, hairy beggarticks (Bidens pilosa L.), a common weed and a member of Asteraceae family was investigated for its allelopathic activity against weedy rice (Oryza sativa f. spontanea Roshev.) and creeping sensitive plant (Mimosa diplotricha C.Wright ex Sauvalle). The extractions were done with 2 solvents, 80% ethanol and dichloromethane, then 4 concentrations (5, 10, 25, and 50 mg mL-1) of each extract were prepared to test with seeds of weedy rice and creeping sensitive plant. The experiment was designed by completely randomized design (CRD) with 4 replica tions and 25 seeds in each replication. After 1 week, germinated seeds were counted, shoot and root length of seedling were measured. Seed vigor index, percentage of germination, and percentage of shoot length and root length inhibition were calculated.

       Our results reveal that 50 mg mL-1 of 80% ethanol extract was the most effective extract which inhibits germination and seedling growth of weedy rice with the percentage of shoot length and root length inhibition of 66.39% and 85.96%, respectively. In contrast, dichloromethane extract (50 mg mL-1) shows more strong allelopathic activity against creeping sensitive plant than ethanolic extract, with the percentage of shoot length and root length inhibition of 95.14% and 83.80%, respectively. It is suggested that the allelochemicals from hairy beggarticks which are responsible for germination and growth inhibitory effects were different groups of compound. This might lead to the development of extraction method of allelochemicals from hairy beggarticks which could be utilized as natural herbicide in weed control in the future.