Pan Yue, Han Xue, Xu Huasen, Wu Wei, Liu Xiaoming, Li Yingchun, Xue Cheng
State Key Laboratory of North China Crop Improvement and Regulation/Key Laboratory for Farmland Eco-Environment of Hebei/College of Resources and Environmental Science, Hebei Agricultural University, Baoding, China.
Key Laboratory of Agro-environment and Climate Change of Agriculture Ministry, Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China.
Front Plant Sci. 2023 Jun 20;14:1186890. doi: 10.3389/fpls.2023.1186890. eCollection 2023.
Late stage nitrogen (N) applications following basic fertilization are commonly used to ensure grain yield and increase grain protein content in wheat. Split N applications at the late growth stage of wheat are an effective measure to improve N absorption and transport and thus increase grain protein content. However, whether split N applications can alleviate the decrease in grain protein content induced by elevated atmospheric CO concentrations (e[CO]) remains unclear. In the present study, a free-air CO enrichment system was used to investigate the effects of split N applications (at booting or anthesis) on grain yield, N utilization, protein content, and the composition of wheat under atmospheric (ACO; 400 ± 15 ppm) and elevated CO concentrations (ECO; 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 ECO conditions. Although the negative effect of e[CO] on grain protein content was not alleviated by split N applications, 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 applications, the gluten content of wheat grains increased by 4.2% and 4.5% when late stage N was applied at the booting stage under ACO and anthesis under ECO conditions, respectively. The results indicate that rational handling of N fertilizers may be a promising approach to coordinating grain yield and quality under the effects of future climate change. However, compared to ACO conditions, the key timing for improving grain quality by split N applications should be postponed from the booting stage to anthesis under e[CO] conditions.
在基肥基础上进行后期施氮，常用于确保小麦产量并提高籽粒蛋白质含量。在小麦生长后期进行分次施氮，是提高氮素吸收和转运从而增加籽粒蛋白质含量的有效措施。然而，分次施氮能否缓解大气CO浓度升高（e[CO]）导致的籽粒蛋白质含量下降尚不清楚。在本研究中，利用开放式空气CO2浓度增高系统，研究了在大气CO浓度（ACO；400±15 ppm）和升高的CO浓度（ECO；600±15 ppm）条件下，分次施氮（在孕穗期或开花期）对小麦籽粒产量、氮素利用、蛋白质含量及组成的影响。结果表明，在ECO条件下，小麦籽粒产量和籽粒氮素吸收量分别增加了5.0%（穗粒数增加3.0%，千粒重增加².0%，收获指数增加1.6%）和4.3%，而籽粒蛋白质含量下降了2.3%。尽管分次施氮未能缓解e[CO]对籽粒蛋白质含量的负面影响，但由于不同蛋白质组分（清蛋白、球蛋白、醇溶蛋白和谷蛋白）中氮素分布的改变，谷蛋白含量有所提高。与不进行分次施氮相比，在ACO条件下于孕穗期进行后期施氮以及在ECO条件下于开花期进行后期施氮时，小麦籽粒的谷蛋白含量分别增加了4.2%和4.5%。结果表明，合理施用氮肥可能是在未来气候变化影响下协调籽粒产量和品质的一种有前景的方法。然而，与ACO条件相比，在e[CO]条件下通过分次施氮提高籽粒品质的关键时期应从孕穗期推迟至开花期。
