Fig. 2. Effect of nutsedge density (nutsedge-cotton ratio) on (A) shoot biomass and on (B) the inverse of shoot biomass of cotton a teach level of ozone exposure (LO3, MO3, and HO3). In (B), the slope of each line is interpreted as a competition coefficient (c).Mean separation for data points, lines, and values of c as in Fig. 1. * and ** indicate P 0.05 and P 0.01, respectively.