Nitrogen utilization efficiency in wheat: A global perspective

Abstract

• New synthesis-analysis offers insights on trends in wheat N utilization efficiency. • A nonlinear model explained wheat grain yield as a function of N uptake (i.e. NUtE). • There are greater opportunities to increase NUtE in fall- than winter-sown wheat. • Increases in NUtE originated from dilution of grain protein concentration. • Identifying the determinants of NUtE will increase yield limited by N uptake. Understanding factors underpinning the variability in nitrogen (N) utilization efficiency (NUtE) [i.e. grain yield per unit of N uptake at maturity (Nup MAT )] is critical to direct future improvements in breeding and agronomic management. To our knowledge, no study has summarized changes in wheat NUtE across a wide range of experimental conditions. We performed a synthesis-analysis using published data to provide a global perspective of NUtE trends in wheat by (i) benchmarking against yield limited by Nup MAT , and (ii) assessing factors contributing to the variation in NUtE. The final database encompassed 55 studies ( n = 529). A nonlinear model explained yield as a function of Nup MAT . The gap between actual yield and Nup MAT -limited yield was negligible at the lowest range of Nup MAT and increased to ∼2000 kg ha −1 as Nup MAT levels increased. Hence, opportunities to enhance yield through improving NUtE would be more likely at greater-than-average yield and Nup MAT levels. The negative correlation between grain protein concentration and the residuals between NUtE and Nup MAT indicated a challenge to increase yield without penalizing grain protein. Further, there are greater opportunities to increase NUtE in fall- than winter-sown wheat. Identifying the determinants of NUtE will enable to narrow the gap between actual and Nup MAT -limited yields.