Effects of elevated carbon dioxide and chronic warming on nitrogen(N)-uptake rate, -assimilation, and -concentration of wheat

Authors: JAYAWARDENA, DILEEPA - University Of Toledo; HECKATHORN, SCOTT - University Of Toledo; Boldt, Jennifer

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/26/2020
Publication Date: 12/1/2020
Citation: Jayawardena, D.M., Heckathorn, S.A., Boldt, J.K. 2020. Effects of elevated carbon dioxide and chronic warming on nitrogen(N)-uptake rate, -assimilation, and -concentration of wheat. Plants. 9(12). Article 1689. https://doi.org/10.3390/plants9121689.
DOI: https://doi.org/10.3390/plants9121689

Interpretive Summary: Wheat, a major crop worldwide, requires a high protein content for excellent baking quality and high nutritional value. Plant nitrogen (N) content during vegetative crop growth directly correlates to wheat grain protein content, and it can be impacted by cultivar selection and environmental conditions. Predicted increases in surface temperature and carbon dioxide concentration (CO2) can negatively impact crop growth and nutrient content. Determining which aspects of plant N uptake and assimilation are most severely impacted by elevated temperature and CO2 can provide useful information to plant breeders to develop new wheat cultivars better adapted to future climate conditions. Plants grown at elevated temperatures and elevated CO2 had the lowest %N and protein concentration. They were able to maintain N-uptake rate but not tissue N concentration, likely due to the inhibition of N assimilation. This suggests crop improvement strategies might focus on developing wheat cultivars which can maintain root N uptake and N assimilation at higher temperatures and CO2 concentrations to maintain or enhance the nutritional quality.

Technical Abstract: Wheat protein concentration is a major determinant of its nutritional quality, and it is largely dependent on the balance among growth, root nitrogen (N) uptake, and N assimilation. Elevated carbon dioxide (eCO2) plus warming is likely to affect the nutritional quality of wheat by altering N metabolism, but this is poorly understood. To investigate this, spring wheat (Triticum aestivum) was grown for three weeks at two levels of CO2 (400 or 700 ppm) and two temperature regimes (26/21 or 31/26 °C, day/night). Plant dry mass, plant %N and protein concentrations, NO3- and NH4+ root uptake rates (using 15NO3 or 15NH4), and whole-plant N- and NO3--assimilation were measured. Plant growth, %N, protein concentration, and root N-uptake rate were each significantly affected only by CO2, while N- and NO3--assimilation were significantly affected only by temperature. However, plants grown at eCO2 plus warming had the lowest concentrations of N and protein, and thus the lowest nutritional quality. These results suggest that one strategy breeding programs can implement to minimize the negative effects of eCO2 and warming on wheat nutritional quality would be to target maintenance of root N uptake at eCO2 and N assimilation at higher growth temperatures.