Abstract: To explore interspecific relationship between invasive and native plants, we conducted a greenhouse experiment with two invasive plants (Alternanthera philoxeroides and Wedelia trilobata) and their native congeners (A. sessilis and W. chinensis) across monoculture and mixture plantings. Biomass and morphological indexes were measured and the interspecific relationships between species were analyzed. The results showed that: (1) Congener and heterogeneric interspecific relationship increased the biomass, root/shoot ratio and number of nodes of A. philoxeroides, but decreased the height and number of nodes of W. trilobata. (2) Congener interspecific relationship decreased the height of A. sessilis and number of nodes of W. chinensis, heterogeneric interspecific relationship increased the biomass, height and number of branches of A. sessilis, but decreased the total biomass and height of W. chinensis. (3) Congener interspecific competition had a positive effect on the growth of A. philoxeroides, while heterogeneric interspecific competition had a positive effect on the growth of A. sessilis. In future studies, relationships of cooperation and competition between invasive and native plants in the field need to be advanced to provide a theoretical basis for prevention and control of invasive plants.

Key words: cucumber seedling, suboptimal temperature, NO₃^- stress, magnesium.