Effects of elevated CO2 and/or ozone on nutrient concentrations and nutrient uptake of potatoes

Potato crops were grown at seven sites across Europe to test the effects of elevated atmospheric carbon dioxide and/or tropospheric ozone concentrations on growth, yield and various aspects of potato tuber quality within the framework of the EC funded programme Changing Climate and Potential Impacts on Potato Yield and Quality (CHIP). Field exposure systems were used to enrich the atmosphere in CO2 and/or ozone. At five of the sites, nutrient element conconcentrations (macronutrients: nitrogen, phosphorus, potassium, calcium, magnesium, and micronutrients: mangenese, zinc, iron) in different parts of plants from the various treatments were analysed. Under elevated CO2, nearly all nutrient elements tended to decrease in concentration. At maximum leaf area, a significant reduction was observed for the concentrations of nitrogen and potassium both in aboveground biomass and in tubers, and for calcium in tubers. Since CO2 enrichment promoted early tuber growth, these effects could in part be attributed to tuber developmental stage. At maturity, potato grown under CO2 enrichment exhibited significantly lower concentrations of nitrogen, manganese and iron in aboveground organs, and of nitrogen, potassium and magnesium in tubers which means a reduction of tuber quality. In contrast to CO2, elevated ozone tended to increase tuber nutrient element concentrations. This was significant for nitrogen and manganese. CO2 effects on tuber biomass increase were more pronounced than CO2 effects on nutrient element decrease. Thus, the total amount of nutrient elements taken up by potato crops increased under elevated CO2. Fertiliser practice in a future, CO2-rich world will have to be adjusted accordingly. (C) 2002 Elsevier Science B.V. All rights reserved.