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

A better understanding of wheat cultivar impact on field N2O 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 N2O emissions, wheat growth, and plant nitrogen uptake were determined. The results showed that both the cumulative and yield-scaled N2O emissions differed significantly among cultivars, varying on average from 1.64 to 2.10 kg N2O -N ha(-1) and 232.65-529.37 mg N2O-N kg(-1), respectively. As the wheat cultivar renewal progressed, the cumulative and yield-scaled N2O 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 N2O 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.