In limited-production regions for maize (Zea mays, L.) crop, late sowing date and low plant densities are progressively adopted. At low plant densities, the expression of prolificacy (i.e., more than one fertile ear per plant) can stabilize maize yield throughout environments. However, the limited adoption of N fertilization can reduce kernel set on the apical (E1) and sub-apical ear (E2) and consequently crop grain yield at low plant densities. Five Argentinian maize hybrids with different degrees of prolificacy (1.37–1.92 ears pl^-1 at 4 pl m^-2 irrigated and without N limitations) were cultivated under contrasting plant densities (4 and 8 pl m^-2) and N fertilization rates (70 and 270 kg N ha^-1) to analyze (i) plant biomass, biomass allocation in E1 and E2 (BA_E1 and BA_E2), and floret differentiation of both ears from floral induction to silking stage, (ii) the anthesis-silking intervals of E1 and E2 (ASI_E1 and ASI_E2) and the silking interval between E1 and E2 (ESI), and (iii) silk extrusion of both ears. From the eight-ligulated leaf stage onwards, low N availability and high density decreased plant biomass and BA_E2 without modifying BA_E1. Additionally, N stress reduced floret differentiation of E2 in the less prolific hybrids (DK-747 and DK-7210). On the contrary, E1 and E2 of the most prolific hybrids (DK-3F22, DK-4F37 and DK-664) showed similar temporal patterns of growth and floret differentiation. These hybrids presented the highest proportion of exposed silks in both ears coinciding with their highest BA_E1 and BA_E2, which possibly modulated silk elongation. Finally, under the most stressful environments, the lower BA_E2 than BA_E1 at silking increased ASI of both ears, ESI and reduced the proportion of plants with silks of E2 exposed to pollen. The latter response (i.e., low proportion of plants with silks extrusion in E2) was more pronounced in less prolific hybrids. Therefore, floret differentiation and BA in E2 of the most prolific hybrids would be more stable in the face of changes in nutritional offer, a prevalent scenario of limited-production regions.

在玉米（Zea mays, L.）作物产量有限的地区，逐渐采用晚播期和低种植密度。在低植物密度下，多产性的表达（即每株植物多于一个可育穗）可以在整个环境中稳定玉米产量。然而，有限地采用氮肥可以减少顶端（E1）和近顶端（E2）的籽粒落粒，从而在低植物密度下减少作物产量。^在不同的植物密度（4 和 8 pl m -2 ）^和N施肥率（70和 270 kg N ha ^-1) 分析 (i) 植物生物量、E1 和 E2 中的生物量分配（BA _E1和 BA _E2），以及从花诱导到抽丝阶段的双穗小花分化，（ii） E1 和 E2 的花丝间隔（ASI）_E1和 ASI _E2 ) 和 E1 和 E2 之间的吐丝间隔 (ESI)，以及 (iii) 双耳的丝挤出。从八舌叶期开始，低氮利用率和高密度降低了植物生物量和 BA _E2而没有改变 BA _E1. 此外，氮胁迫降低了低产杂种（DK-747 和 DK-7210）中 E2 的小花分化。相反，最多产的杂种（DK-3F22、DK-4F37 和 DK-664）的 E1 和 E2 显示出相似的生长和小花分化的时间模式。这些杂种在双耳中呈现出最高比例的暴露丝绸，与其最高的 BA _E1和 BA _E2一致，这可能调节了丝绸的伸长率。最后，在压力最大的环境下，BA _E2低于 BA _E1在吐丝时增加了双穗的 ASI、ESI 并降低了 E2 丝暴露于花粉的植物比例。后一种反应（即在E2 中挤出丝的植物比例较低）在产量较低的杂种中更为明显。因此，面对营养供应的变化，高产杂交种的 E2 中的小花分化和 BA 将更加稳定，这是有限生产地区的普遍情况。