Effects of low levels of ozone on plant competition.
Monocultures and mixtures of crimson clover and ryegrass (Lolium multiflorum) were grown in filtered air or 0.03 or 0.09 p.p.m. O3 concentrations for 6 wk. The yield and leaf area of ryegrass in mixtures was less affected by O3 than was that of clover so that the proportion of ryegrass was greater in 0.09 p.p.m. O3. The total dry wt. yield, leaf area, LAR and tiller number were less depressed by O3 in mixtures than in monocultures. The results fitted the de Wit model of competition where RYT = 1 and krc = 1/kcr.