Fig 6. Mean (± standard deviation) relative growth rate (RGR) of Lemna (bars) in the four phosphorus treatments when grown as monoculture and in competition with Azolla or Ricciocarpus (triangles represent mean RGR of the competitor) In the competition treatments, 50% of the surface was initially covered by Lemna (L. minor/gibba) and 50% by either Azolla (A. filiculoides) or Ricciocarpus (R. natans).

Different letters within each panel indicate significant differences (p<0.05) found through pairwise comparisons.