Optimizing the nitrogen management of cytoplasmatic male-sterility winter wheat hybrids to improve yield and nutrient use efficiency

Sustainable cereal production requires genotypes that have enhanced nitrogen use efficiency (NUE). The aim of this study was to compare a new cytoplasmatic male-sterility (CMS) wheat hybrid with a conventional pure line cultivar to assess its agronomic and productive performance and its NUE, under several N-fertilization rates (20 top dressed N fertilization strategies, from 0 to 231 N ha-1) applied between tillering and the stem elongation growth stage). Field experiments were carried out in the North West of Italy over two growing seasons (2023 and 2024). The grain yield of the CMS hybrid outperformed the conventional cultivar by 6 % and 16 % in 2023 and 2024, respectively. The lower rainfall in 2023 increased the N availability, due to reduced leaching. This reduced the yield performance of the hybrid genotype, due to the higher incidence of lodging. The grain yield advantage of the hybrid was linked to a higher number of kernels per ear (+11%) and heavier grain weight (+36%), although the ear density was on average 6% lower than that of the conventional wheat, as a consequence of lower seeding density. The yield gain of the CMS hybrid was more consistent at the reduced N rate, and this genotype exhibited a superior NUE compared to the conventional genotype. However, the higher NUE of the CMS hybrid needs to be enhanced through tailored fertilization management, which could lead to both economic and environmental advantages for cereal cropping systems. This study highlights how the rational adaptation of fertilization strategies, in accordance with the key drivers for the cereal cropping system management, is required to overcome the drawbacks and to fully exploit the potential of this genetic innovation.