Allelopathic potential of native invasive plants: The evidence from southern China

In bioassays, the allelopathic potential of seven plant species were tested. These species were 4-native harmful plant species (Merremia umbellata, Byttneria aspera, Millettia dielsiana, Millettia pachycarpa), 2-exotic invasive species (Mikania micrantha, Ipomoea cairica) and one harmless native species (Mussaenda pubescens)]. Two recipient species were Chinese cabbage (Brassica rapa L. ssp. Chinensis) and lettuce (Lactuca sativa L. var. capitata L.). The results showed that the four native invaders have allelopathic potential like the two exotic invasive plants. The allelopathic potential differed among these species and was dependent on the concentrations of aqueous extracts. M. dielsiana had the strongest allelopathic potential among the seven species relative to the control. However, the allelopathic potential of some native invaders was close to the harmless native species M. pubescens. This indicates that besides allelopathy, other plant traits may also facilitate the harmful plants to suppress other plants. Further research is needed to explore the mechanisms underlying the allelopathic potential of native invasive plants and to focus on dynamics of allelochemicals from native invasive plants in competitive condition.