Effects of carbon dioxide concentrations on three grass species grown in mixture in two soil types at different ozone concentrations or temperatures

Abstract

A seed mixture of Phleum pratense L., Lolium perenne L. and Festuca pratensis Huds. was grown in spaghnum peat or sandy soil in six growth chambers placed in a greenhouse compartment. Two different experiments were performed. Increasing the CO2 concentration from 375 to 740 μmol mol−1 increased the total dry weight of the grass mixture by about 30%, while an increase in the O3 concentration from < 10 to 50 nmol mol−1 decreased the dry weight by 18% as a mean in both experiments. The relative dry weights of the three species were not significantly affected by elevated CO2 concentrations at low O3, while Lolium increased its relative dry weight at high O3concentrations at low CO2 on the expenditure of Phleum dry weight. CO2 enrichment counteracted some of this O3 effect. No significant interaction between CO2 concentration and temperature (14 and 19°C mean temperature) was found with respect to the dry weights of the three species. The soil type had generally no influence on the effect of CO2 and O3. However, plant growth was significantly slower in sandy soil than in peat.