Water deficiency with nitrogen enrichment makes Wedelia trilobata to become weak competitor under competition.

Global environmental changes are believed to promote the invasion of many invasive plant species, especially under nitrogen enrichment conditions. However, it is unclear, how invasive plant species respond to nitrogen enrichment along with water deficit. In this study, competition of invasive plant (Wedelia trilobata, W_T) was studied with its congener native (Wedelia chinensis, W_C) under three levels of nitrogen (control, additional and double additional), two levels of water (normal and deficit) and three types of culture (single, mono and mixed). The result showed that under control treatment and additional nitrogen, the growth of W_T was 30% higher than W_C in all cultures but under additional nitrogen along with water deficit the growth of W_T was 20% lower than W_C within single plant and monoculture. Under competition, biomass, specific leaf area, root-to-shoot ratio, leaf chlorophyll content and leaf nitrogen of W_T were 20–40% decreased as compared to W_C under water deficit along with nitrogen addition treatments. These results indicated that competitive interaction between W_T and W_C was altered by additional nitrogen together with water deficit. It provides exceptional evidence that vigorous invasive species become weak competitor under additional nitrogen along with water deficit. [ABSTRACT FROM AUTHOR]