Application of the full nitrogen dose at decreasing rates by foliar spraying versus conventional soil fertilization in common wheat

Foliar fertilization is increasingly recognized as a sustainable agronomic practice, yet its full potential to enhance nitrogen use efficiency (NUE), reduce application rates, and improve wheat grain quality remains largely underexplored. This study evaluated a two-year field trial comparing nitrogen fertilization applied solely through repeated foliar spraying at reduced doses (96, 80, and 64 kg N ha −1 ) using urea-ammonium-nitrate (UAN) compared to conventional soil fertilization at a standard rate of 160 kg N ha −1 . Here it was demonstrated that foliar application at 96 kg N ha −1 achieved grain yields comparable to conventional fertilization (6.80 vs. 7.05 t ha −1 ) while slightly improving root and shoot growth. Reduced doses also significantly enhanced the glutenins-to-gliadins ratio, total glutenins content (+14 %), and nitrogen use efficiency (NUE: 118.1 vs. 47.5 kg grain DM kg −1 N supplied) but with a 14 % yield reduction at the lowest fertilizer dose (64 kg N ha −1 ). These findings demonstrate that foliar fertilization can maintain wheat productivity while reducing nitrogen input by up to 40 %, enhancing NUE and grain quality. This strategy also provides fertilizer savings and environmental benefits, with potential applications in drought-prone areas. Future research should focus on optimizing application rates and assessing long-term economic and environmental impacts. • At −40 % of the foliar N dose, grain yield was comparable to conventional soil fertilization. • Reduced foliar N doses improved root length density in the arable layer. • At reduced foliar N doses, glutenins and glutenins/gliadins were increased. • At −60 % of the foliar N dose, NUE was maximized, but yield reduced.