Comparative allelopathic and competitive abilities of 3-native forage legumes and the invasive weed Bidens pilosa L.
Bidens pilosa L., an invasive exotic weed, has caused substantial damage to the ecosystem in Southern China. Till now there is no effective way to control this invasive plant. In this study laboratory bioassay and pot experiments were conducted to compare allelopathic potentials and competitive abilities of the B. pilosa and three native forage legumes (Vicia villosa Roth, Medicago sativa L. and Trifolium repens L.). Allelopathic activity was evaluated by determining the phytotoxic effects of aqueous leachates of fresh leaves and litter leachate in water-agar sandwich on seed germination and seedling growth. Competitive ability was determined by measuring the biomass of plants grown in pots at different densities and proportions for 45 d. At the same concentration of leachates, V. villosa, M. sativa and T. repens showed more inhibitory effects on B. pilosa than the effects of B. pilosa on the three legume plants. Based on the relative yield, relative yield total and aggressivity, the order of the competitive ability was: V. villosa > M. sativa > T. repens. V. villosa can be used as biological alternative material to manage the invasive plant B. pilosa.