Modelling climate change impacts on yield and quality of crops based on leaf photosynthesis with acclimation to elevated CO2

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Predicted changes in average values of climate factors (increased atmospheric CO2 concentration, increased temperature, altered precipitation patterns) and predicted changes in climatic variability (frequencies, duration and degree of extremes such as heat and frost periods, droughts, floods and storms) will impact on the yield and quality of agricultural crops. Whereas effects of many of these climatic factors on primary production of agricultural crops have been investigated, little is known about the impact on the chemical composition of plant biomass. Even less is known about how to model and simulate climatic effects on the plant internal transport and transformation processes of chemicals (i.e. macro- and micro-nutrients, sugars, starch, phenolics) that determine crop quality parameters (e.g. carbon to nitrogen (C/N) ratio of grains). Such process knowledge is necessary to predict the quality of future crop yields. The project P5, therefore, will develop and test a new crop growth model based on improved sub-models of leaf photosynthesis and resource allocation dynamics. The model focus will be on the acclimation of photosynthesis to elevated CO2 concentrations which leads inter alia to lower leaf N contents and higher C/N ratios of grains. The new sub-models will extend the crop models CERES, SPASS, SUCROS and GECROS that are part of the agro-ecosystem model Expert-N.