Residual effects of invasive weed Yellowtop (Flaveria bidentis) on forage plants for ecological restoration

In bioassays, we investigated the residual effects of yellowtop (Flaveria bidentis), a new invasive weed in China and its effects on test forage species for restoration of sites invaded by exotic weeds. The relative contributions of leaves and roots to the residual effects of yellowtop were evaluated. We found that the sensitivity to yellowtop residues was species dependent and there was no effect on the germination and initial growth of Lolium perenne, Medicago sativa and Sorghum vulgare × S. sudanense hybrid, but other species (Lactuca indica,Trifolium repens and Euchlaena mexicana) seedlings were more sensitive, but there was little influence on itself. The phytotoxic activity depended on the extract concentration and the extract sources. The yellowtop root residues were more inhibitory than leaf, helping to explain its residual effects on the surrounding soil. Screening of forage plants resistant to these allelochemicals may improve their success in ecological restoration after yellowtop weed invasion.