Ferguson, Justine2016-01-152016-01-152015https://hdl.handle.net/10182/6788The concentration of CO₂ in the atmosphere is rising each year and the CO₂ level may double in the next century. The rising CO₂ concentration causes an increase in carbon assimilation due to increased efficiency of photosynthesis and a reduction in photorespiration. In this experiment, the effect of elevated CO₂ was impacted by the amount of NO₃⁻ supplied to common bean and wheat. At optimal concentrations of NO₃⁻ supplied, common bean grown at elevated CO₂ concentrations had up to a 73% increase in dry matter production and an equivalent amount of total nitrogen and soluble protein in the lamina compared to common bean grown at ambient CO₂ concentrations. However, common bean grown at elevated CO₂ concentrations with low rates of NO₃⁻ supplied had an equivalent dry matter production and total nitrogen content was greatly decreased compared to those grown at ambient CO₂ concentrations. The wheat with optimal supplied NO₃⁻ concentrations at elevated CO₂ concentrations had up to a 89% increase in dry matter production, a 39% increase in lamina total nitrogen and an equivalent total amount of soluble protein in the lamina compared to wheat grown at ambient CO₂ concentrations. With low NO₃⁻ supplied, the wheat grown at elevated CO₂ concentration had equivalent dry matter production and total nitrogen content to the wheat grown at ambient CO₂ concentrations. These results show the importance of nitrogen availability on the performance of plants under elevated CO₂ conditions.enhttps://researcharchive.lincoln.ac.nz/pages/rightscarbon dioxideCO2 elevated concentrationcommon beanwheatNitrogennitratedry matter productionlegumesDissertationANZSRC::070304 Crop and Pasture Biomass and BioproductsANZSRC::0607 Plant BiologyQ112908793