AUTHOR=Pan Yue , Han Xue , Xu Huasen , Wu Wei , Liu Xiaoming , Li Yingchun , Xue Cheng 

TITLE=Elevated atmospheric CO2 delays the key timing for split N applications to improve wheat (Triticum aestivum L.) protein composition

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1186890

DOI=10.3389/fpls.2023.1186890

ISSN=1664-462X

ABSTRACT=Late nitrogen (N) application following basic fertilization is commonly performed to ensure grain yield and increase grain protein contentof wheat. Split N application at the late growth stage of wheat is an effective measure to improve N absorption and transport and thus enhance grain protein content. However, whether split N application can alleviate the decrease in grain protein content induced by elevated atmospheric CO2 concentrations (e[CO2]) remains unclear. In the present study, a free-air CO2 enrichment system was used to investigate the effects of split N application (at booting or anthesis) on grain yield, N utilization, protein content and its composition of wheat under atmospheric (ACO2; 400 ± 15 ppm) and elevated CO2 concentrations (ECO2; 600 ± 15 ppm). The results showed that wheat grain yield and grain N uptake increased by 5.0% (being grains per ear by 3.0%, 1000-grain weight by 2.0% and harvest index by 1.6%) and 4.3%, respectively, whereas grain protein content decreased by 2.3% under ECO2 conditions. Although the negative effect of e[CO2] on grain protein content was not alleviated by split N application, gluten protein content was enhanced due to the alteration of N distribution in different protein fractions (albumins, globulins, gliadins and glutenins). Compared to that without split N application, the gluten content of wheat grains increased by 4.2% and 4.5% when late N was applied at the booting stage under ACO2 and anthesis under ECO2 conditions, respectively. The results indicate that rational handling of N fertilizers may be a promising approach to coordinating the grain yield and quality of wheat under future climate change conditions. However, compared to ACO2 conditions, the key timing for improving grain quality by split N application should be postponed from the booting stage to anthesis under e[CO2] conditions.