Field studies on the interaction of mineral nitrogen supply and free air CO2 enrichment on grain protein content and grain protein composition of winter wheat

• Applicants: Dr. Remigius Manderscheid; Professor Dr. Christian Zörb
• Subject Area: Plant Cultivation, Plant Nutrition, Agricultural Technology ; Plant Physiology
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 260113066

The rise of the atmospheric CO2 concentration ([CO2]) improves wheat growth and yield but affects grain protein concentration (GP%) by decreasing gluten concentration in the grain 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 since the increase in grain dry weight is higher than the increase in N acquisition. Furthermore it is discussed that elevated [CO2] may reduce N acquisition. The largest amount for grain N comes from the remobilization of organic N accumulated in the vegetative tissue until anthesis. A smaller part is attributed to the translocation of N which is assimilated between anthesis and grain maturity. In this study the effects of elevated [CO2] using free air CO2 enrichment (FACE) and three levels of mineral nitrogen supply (60-350 kg N ha-1) on nitrogen remobilization and translocation and on concentration and composition of grain protein will be investigated. Remobilization of N will be quantified from the dry weights of the leaves and stems and the difference in N concentration between anthesis and grain maturity. It will be examined whether elevated [CO2] decreases N remobilization at low N supply due to an increase of the stem fraction and a decrease of the leaf N concentration. 15N labeling of the N fertilizer added at flowering will be used to investigate whether CO2 enrichment affects N translocation especially at medium level of N fertilization. We will test whether the decrease in GP% by CO2 can be prevented by using a very high level of N fertilization. In all these experiments solid calcium ammonium nitrate will be used. In an additional experiment plants will be supplied with a usual level of N fertilization (180 kg ha-1) by using only nitrate-N. The objective of this study is to determine whether the effect of elevated [CO2] on N uptake, growth and GP% of wheat is strongly influenced by the N-form. Beside plant growth measurements environmental conditions will be recorded enabling the later use of the data for modelling plant growth and grain quality under climate change.

• DFG Programme: Research Grants
• Participating Person: Professor Dr. Hans-Joachim Weigel