Less N2O emission from newly high-yielding cultivars of winter wheat.

A better understanding of wheat cultivar impact on field N 2 O emissions could provide important information for cultivar improvement and selection to meet food security and greenhouse gas (GHG) mitigation. A 2-year field experiment was carried out from 2015 to 2017 on 12 leading cultivars released in the major winter wheat cropping regions of China since the 1940s. Field N 2 O emissions, wheat growth, and plant nitrogen uptake were determined. The results showed that both the cumulative and yield-scaled N 2 O emissions differed significantly among cultivars, varying on average from 1.64 to 2.10 kg N 2 O–N ha−1 and 232.65–529.37 mg N 2 O–N kg−1, respectively. As the wheat cultivar renewal progressed, the cumulative and yield-scaled N 2 O emissions declined significantly at the relative decrease rates of 0.2% yr−1 and 0.9% yr−1, respectively. In addition to wheat grain yield and biomass, amount of plant N uptake has been enhanced significantly over the past sixty years. The spike number per unit area, leaf dry matter, net photosynthesis rate, and transpiration rate also all increased, whereas wheat plant height decreased over the decades. Our findings demonstrate that lower N 2 O emissions can primarily be attributed to the greater N uptake of the newly high-yielding wheat cultivars, suggesting a great chance of ensuring food security and GHG mitigation simultaneously through cultivar selection and improvement. [Display omitted] • Both the cumulative and yield-scaled N 2 O emissions were lower with new wheat cultivars compared to old ones. • The reduction effects of yield-scaled N 2 O emissions with the cultivar improvement overperformed the cumulative N 2 O emissions. • Wheat yield and N uptake increased significantly along with the cultivar improvement. • Lower N 2 O emissions with new cultivars was associated with higher productivity and N uptake, and lower soil N availability. [ABSTRACT FROM AUTHOR]