Partitioning of dry mass and leaf area within plants of three species grown at elevated CO2

1. We tested the hypothesis that the net partitioning of dry mass and dry m ass:area relationships is unaltered when plants are grown at elevated atmos pheric CO2 concentrations. 2. The total dry mass of Dactylis glomerata, Bellis perennis and Trifolium repens was higher for plants in 700 compared to 350 mu mol CO2 mol(-1) when grown hydroponically in controlled-environment cabinets. 3. Shoot:root ratios were higher and leaf area ratios and specific leaf are as lower in all species grown at elevated CO2. Leaf mass ratio was higher i n plants of B. perennis and D. glomerata grown at elevated CO2. 4. Whilst these data suggest that CO2 alters the net partitioning of dry ma ss and dry mass:leaf area relationships, allometric comparisons of the comp onents of dry mass and leaf area suggest at most a small effect of CO2. CO2 changed only two of a total of 12 allometric coefficients we calculated fo r the three species: v relating shoot to root dry mass was higher in D. glo merata, whilst v relating leaf area to total dry mass was lower in T. repen s. 5. CO2 alone has very little effect on partitioning when the size of the pl ant is taken into account.