Abstract Understanding factors underpinning the variability in nitrogen (N) utilization efficiency (NUtE) [i.e. grain yield per unit of N uptake at maturity (NupMAT)] 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 NupMAT, 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 NupMAT. The gap between actual yield and NupMAT-limited yield was negligible at the lowest range of NupMAT and increased to ∼2000 kg ha−1 as NupMAT levels increased. Hence, opportunities to enhance yield through improving NUtE would be more likely at greater-than-average yield and NupMAT levels. The negative correlation between grain protein concentration and the residuals between NUtE and NupMAT 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 NupMAT-limited yields.

中文翻译：

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小麦氮素利用效率：全球视野

摘要 了解支持氮 (N) 利用率 (NUtE) 变异性的因素 [即成熟时每单位 N 吸收的粮食产量 (NupMAT)] 对于指导未来育种和农艺管理的改进至关重要。据我们所知，没有任何研究总结了小麦 NUtE 在各种实验条件下的变化。我们使用已发表的数据进行了综合分析，通过 (i) 以 NupMAT 限制的产量为基准，以及 (ii) 评估导致 NUtE 变化的因素，以提供小麦 NUtE 趋势的全球视角。最终数据库包含 55 项研究（n = 529）。非线性模型将产量解释为 NupMAT 的函数。在 NupMAT 的最低范围内，实际产量与 NupMAT 限制产量之间的差距可以忽略不计，并且随着 NupMAT 水平的增加而增加到~2000 kg ha-1。因此，在高于平均产量和 NupMAT 水平的情况下，更有可能通过改善 NUtE 来提高产量。谷物蛋白质浓度与 NUtE 和 NupMAT 之间的残留量之间的负相关表明，在不损害谷物蛋白质的情况下提高产量是一项挑战。此外，与冬播小麦相比，秋播小麦更有可能增加 NUtE。确定 NUtE 的决定因素将能够缩小实际产量和 NupMAT 限制产量之间的差距。与冬播小麦相比，秋季小麦有更多的机会增加 NUtE。确定 NUtE 的决定因素将能够缩小实际产量和 NupMAT 限制产量之间的差距。与冬播小麦相比，秋季小麦有更多的机会增加 NUtE。确定 NUtE 的决定因素将能够缩小实际产量和 NupMAT 限制产量之间的差距。