Field experiments on processes of the interaction of nitrogen fertilisation and elevated atmospheric CO2 concentrations on concentration and composition of grain protein of wheat 

As previously published, the rise of the atmospheric CO2 concentration will increase grain yield of wheat, however, grain protein content and thus grain quality will be impaired. This will be a substantial problem for food security, which has to be managed by cultivation and breeding measures.  

Background and Objective

In order to solve the problem a detailed understanding of the processes is necessary, which will be worked on in this project. The effect of elevated CO2 concentration will be investigated on nitrogen uptake and remobilisation to the grain. It will be tested whether the negative effect of elevated CO2 on grain quality can be prevented by changing the amount or type of nitrogen fertilization.

It is suggested that the reduction of photorespiration under high CO2 causes a decreases of nitrate assimilation. This process and other mechanisms are thought to be responsible for the decrease of grain protein concentration under elevated CO2. The problem may be solved if the plant takes up only ammonium. This will be tested by using different forms of nitrogen fertilizer.

Approach

Winter wheat will be grown on the experimental field site of the Thünen-Institute with ambient (ca. 395 ppm) and elevated CO2 concentration (600 ppm)over two years. Nitrogen fertilisation will be an additional treatment factor by using different levels (low, medium, abundant) and types of nitrogen (only ammonium or mixture of nitrate and ammonium).

Data and Methods

The investigations comprise

• short-term analysis of the activity of nitrate reductase
• measurements of accumulation of organic nitrogen in the vegetative shoot (leaf and stem) until anthesis
• measurement of nitrogen uptake from anthesis until grain maturity
• analysis of remobilsation of shoot N to the grain

Our Research Questions

Does CO2 enrichment decrease nitrate reductase activity  and thus N assimilation of the whole plant?

Is there an interaction of CO2 enrichment with nitrogen supply, i.e. does the CO2 related effect on grain nitrogen concentration decrease with increasing nitrogen supply and can the negative CO2 effect on grain nitrogen be removed by adding more fertilizer.

Can the negative effect of CO2 enrichment on grain quality be eliminated by feeding the plants with ammonium instead of nitrate?

Results

• There was no decrease but an increase of the nitrate reductase activity under elevated CO2 concentration
• Seasonal water use was decreased up to 15% under high N supply, however, there was no effect under N deficiency. Similarly, water use efficiency was more increased by CO2 enrichment under high N (>30%) than under low N (20%).

Thünen-Contact

• Manderscheid, Remigius Institute of Biodiversity

Involved Thünen-Partners

• Dier, Markus Institute of Biodiversity
• Erbs, Martin Institute of Biodiversity
• Weigel, Hans-Joachim Institute of Biodiversity

Involved external Thünen-Partners

• Julius Kühn-Institut - Bundesforschungsinstitut für Kulturpflanzen (JKI)
  (Quedlinburg, Deutschland)
• Universität Hohenheim
  (Hohenheim, Deutschland)
• Technische Universität Braunschweig
  (Braunschweig, Deutschland)

Funding Body

• Deutsche Forschungsgemeinschaft (DFG)
  (national, öffentlich)

Duration

5.2014 - 2.2019

More Information

Projekt type:
Project funding number: MA 1736/5-1
Project status: finished

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