Fig. 4. The effect of ultraviolet-B (UVB) light on the relationship between reproductive and vegetative biomass per Italian ryegrass plant growing in (A) nontreated (control) plots and (B) herbicide-treated plots. Both parental populations were pooled for analysis. Regression equations: (A) UVB–: y = 0.1354x + 0.0013, R² = 0.95, P = 0.001, SE of the slope = 0.01; UVB+: y = 0.1102x + 0.0015, R² = 0.89, P = 0.001, SE of the slope = 0.01; (B) UVB–: y = 0.1011x + 0.0227, R² = 0.31, P < 0.05, SE of the slope = 0.05; UVB+: y = –0.0461x + 0.0276, R² = 0.06, P > 0.05.