Ozone and Sulfur Dioxide Effects on Tall fescue: I. Growth and Yield Responses

Abstract

AbstractThe effects of ozone (O3) and sulfur dioxide (SO2) on growth and yield components of tall fescue (Festuca arundinacea Schreb. ‘Alta’) were studied in a greenhouse experiment. Four O3 treatments ranging from 0 to 0.30 ppm in equally spaced intervals and two SO2 treatments, 0 and 0.10 ppm, were arranged factorially in a randomized complete block design utilizing three blocks. Each block was exposed to the pollutants 6 h/d, once a week, for 12 weeks. Statistical analysis was by analysis of variance and regression techniques.Ozone significantly affected root/shoot ratio and all dry weight fractions. A reduction of total dry weight of 52.5% was found due to 0.30 ppm O3. A cubic regression model of O3 concentration on total dry weight accounted for 93% of the variation in total dry weight. Partitioning the dry weight into shoot and root components revealed a reduction in shoot weight of up to 46% and a reduction in shoot weight of up to 46% and a reduction in root weight of up to 63.6% due to the high‐O3 treatment. Both variables had significant cubic regressions of O3 on dry weight with the cubic model accounting for 93 and 89% of the variation in shoot and root weights, respectively. Root/shoot ratio declined from 0.58 for control plants to 0.41 for plants exposed to 0.30 ppm O3. A significant cubic regression of O3 on root/shoot ratio accounted for 78% of the variation in this variable. Tiller weight was also affected adversely by O3 with a linear decrease (r2 = 0.85) of > 44% at the highest O3 level. SO2 also affected tall fescue, but not nearly as severely as O3. Total dry weight was reduced by 7.3% due to SO2. Root weight was decreased by 11%, but shoot weight was unaffected. Root/shoot ratio was lowered about 7% due to the pollutant. Weight per tiller was unaffected by SO2. Number of tillers was significantly reduced by an interaction of the two pollutants. Neither O3 or SO2 had an effect singly, but at the high O3 level, the addition of SO3 caused an 18.6% reduction in number of tillers. This was the only significant pollutant interaction noted.