The influence of N timing and N rate on yield formation and grain-filling procedures in winter and spring-sown oats is unclear. Factorial trials investigating the effect of six rates of applied N fertiliser (0,30. 60. 90. 120 and 150 kg N ha⁻¹) applied at three timings (Zadoks GS 21, 30 and 50) were conducted at four spring sown sites and three winter sown sites (Cv Husky) over the period 2016–2019 in the east of Ireland.

Significant interactions were frequently observed on grain yield following spring and winter sowing, associated with increases in grain number where N was applied at early growth stages (GS 21, GS30) relative to GS50 application. This was linked with increases in panicles/m² in response to available N during early developmental periods. Grain weight was maintained as the level of N applied at GS50 increased with reductions observed at earlier applications, but had no effect on yield.

Responses to applied N rate were in the range of 0.5–1.9 t ha⁻¹ in spring sown crops and 1.2–3 t ha⁻¹ in winter sown crops, with grain yield reducing by 0.5–2.1 t/ha ⁻¹ (spring) and 1.2–1.5 t ha⁻¹ (winter) as N application was delayed. N application timing impacted spikelet and grain number per panicle in winter crops, with spring crops unaffected.

The relative importance of panicle number when spring sown, and grains/panicle when winter sown, is also discussed. This paper highlights the role of N application during early developmental in increasing the yield components contributing to grain number.

施氮时间和施氮量对冬春燕麦产量形成和灌浆程序的影响尚不清楚。在四个春季播种地点进行了在三个时间（Zadoks GS 21、30 和 50）施用的六种氮肥施用率（0,30. 60. 90. 120 和 150 kg N ha ^-1 ）的影响的因子试验以及 2016-2019 年期间爱尔兰东部的三个冬季播种地点 (Cv Husky)。

春季和冬季播种后谷物产量经常观察到显着的相互作用，这与在早期生长阶段（GS 21，GS30）施用 N 相对于 GS50 施用的谷物数量增加有关。这与在早期发育期间响应可用N而增加的穗数/m ^2相关。随着在 GS50 下施用的 N 水平随着早期施用中观察到的减少而增加，谷物重量保持不变，但对产量没有影响。

施氮量的响应范围为春播作物 0.5-1.9 t ha ^-1和冬季播种作物 1.2-3 t ha ^-1，粮食减产 0.5-2.1 t/ha ^-1（春季）和 1.2–1.5 t ha ^-1（冬季），因为施氮延迟。施氮时间影响冬季作物的小穗和每穗粒数，春季作物不受影响。

还讨论了春播时穗数和冬播时谷粒/穗数的相对重要性。本文强调了在早期发育过程中施氮在增加对籽粒数量有贡献的产量成分中的作用。