The rise of the atmospheric CO2 concentration ([CO2]) improves wheat growth and yield but affects grain protein concentration (GP%) by decreasing gluten concentration and thus baking quality. The reasons for the negative CO2-effect on grain quality are still under debate. It is discussed that the decrease of GP% under elevated [CO2] results from growth dilution and /or a reduction of N acquisition. The objectives of this project are to investigate the N-acquisition and remobilization to the grain to understand the processes involved in the decrease of GP% under FACE. We have started a two-year (2014-2015) FACE-experiment (400 ppm/600 ppm) with winter wheat grown at three N levels (ca. 60/200/340 kg ha-1) and under well watered conditions. During the growing period in 2014 destructive plant sampling was done once a month until grain maturity and crop growth and N% of different plant fractions were measured. Seasonal course of LAI strongly depended on N supply and was hardly influenced by CO2 enrichment. [CO2] elevation increased leaf and stem biomass by ca. 5 – 14 %, but the CO2 effect did not increase with N supply as expected. N% in green leaves was slightly more decreased by [CO2] elevation than N% in stems. Total amount of N in the shoot at anthesis strongly increased with N supply and CO2 enrichment had a smaller effect (+4%) at the highest N level than at 60 and 200 kg N ha-1 (+10%). In addition, data from the first test year on N remobilization and on GP% will be presented.
