Effects of nutrient supply (NPK) on spring wheat response to elevated atmospheric CO2

The effects of increased atmospheric CO2 on crop growth and dry matter allocation may change if nutrient supply becomes insufficient for maximal growth. Increased atmospheric CO2 may also cause changes in minimum nutrient concentration in plant tissue and hence in the nutrient use efficiency or yield-nutrient uptake ratios of crops. To study these effects for spring wheat, pot experiments have been carried out in two glass houses at ambient and doubled CO2 concentration. Wheat plants were grown at different supplies of N, P or K. Doubling of ambient CO2 resulted in a large increase in total biomass (+70%) and grain yield when the nutrient supply was optimum. With strong N and K limitation this CO2 effect was about halved and with strong P limitation it became almost nil. Doubling of ambient CO2 resulted in a 10% lower minimum N concentration in plant tissue and in no change in the minimum P concentration.