Yield and quality characteristics of bahiagrass (Paspalum notatum) exposed to ground-level ozone

Early and late season-planted bahiagrass (Paspalum notatum Flugge, cultivar `Pensacola') were grown in open-top chambers (OTC) to which added air had been carbon-®ltered (CF), representative of that found at pristine air quality sites; non-®ltered (NF), characteristic of ambient air in Auburn, AL and representative of that found in rural agricultural areas; or enriched with ozone (O3) to twice-ambient O3 concentration (2X), representative of that found in the vicinity of large metropolitan areas. Primary-growth and regrowth forages from each planting were harvested periodically throughout the experiment from each of six OTC (two OTC/air treatment). Mean daytime (09:00±21:00 h) O3 concentrations over the entire 24-week experiment (7 May±23 October 1997) were 22, 45 and 91 Zl lÿ1, respectively, for CF, NF and 2X treatments. Mean daytime ambient O3 concentrations peaked in mid-May and again in late August±late September at 50± 60 Zl lÿ1, and highest individual ambient O3 concentrations were recorded in late June, late July, late August and mid-September at 90 Zl lÿ1. Dry matter (DM) yield was greater for CF than for NF primary-growth forage, and concentrations of neutral detergent ®ber (NDF) were higher in 2X than in NF primary-growth and regrowth forages from the early-season planting. Concentration of acid detergent ®ber (ADF) tended to be higher in 2X than in NF primary-growth forage and was higher in 2X than in NF regrowth forage, whereas acid detergent lignin (ADL) concentration was higher in 2X than in NF primary-growth forage and tended to be higher in 2X than in NF regrowth forage from the early-season planting. Crude protein (CP) concentrations were lower in CF than in NF regrowth forage from the early-season planting and in CF than in NF primary-growth forage from the initial harvest of the late-season planting. No differences were observed among treatments in DM yield or concentrations of cell wall constituents in primary-growth or regrowth forages from the late-season planting, although concentrations of CP, NDF and ADF tended to be higher in 2X Animal Feed Science and Technology