For the maize ( L.) crop, tillering is promoted in resource-abundant seasons (e.g., rainfalls, nutrient availability) at low plant densities. For this crop husbandry, farmers rarely use nitrogen (N) fertilization. Particularly, the impact of tillering on N economy processes and the effects of N availability on grain yield generation of tillered maize crops have yet to be studied. (i) To compare the evolution of biomass and N uptake for tillered and de-tillered (manually removed) maize crops, and (ii) to evaluate the impact of tillers on nitrogen internal efficiency for biomass (NIE), grain yield (NIE) harvest index (HI) and N harvest index (NHI). Two irrigated field experiments in different cropping seasons (2017–2018 and 2018–2019) with a tillering-prone maize hybrid were conducted in Buenos Aires, Argentina. Treatments were a combination of plant density [3 levels, 4 pl m = D4; 2 pl m = D2, including an additional tiller removal treatment during the whole tillering window at D2, D2(-T)] and two soil N availabilities [unfertilized= 60 kg N ha of native soil N (N-) and fertilized= 220 kg N ha of native soil + applied N (N+)]. Biomass accumulation, N uptake, HI, NHI, grain N concentration (GrainN%), NIE and NIE were analyzed at the shoot (main shoot and tillers) and crop levels. At D2 with N+, tillered crops had greater biomass and N uptake than non-tillered crops but did not compensate for the density reduction compared to D4. NIE of tillers was similar to that of main shoots, but HI, NIE and NHI of tillers were lower than those of main shoots. A negative relationship between crop NIE and GrainN% was sustained for main shoots, but not for tillers due to the low and variable HI of these secondary shoots. In low-density maize management scenarios, tillers increase resource capture in resource-abundant seasons, generating greater crop biomass through a sustained NIE. However, an intrinsic lower HI of tillers (and NIE) versus main shoots decreases NIE of tillered crops. Knowledge gaps regarding the impact of tillers on N economy of maize crops were answered for the first time. New issues arise: to compare the N dilution curves for main shoots and tillers and to quantify post-flowering N uptake of tillers and N remobilization from tillers to main shoots.

中文翻译：

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低密度玉米作物的分蘖和氮经济

对于玉米 (L.) 作物来说，在资源丰富的季节（如降雨、养分供应），植物密度较低，会促进分蘖。对于这种作物饲养，农民很少使用氮肥。特别是，分蘖对氮经济过程的影响以及氮素有效性对分蘖玉米作物产量的影响还有待研究。 (i) 比较分蘖和去分蘖（手动去除）玉米作物的生物量和氮吸收的演变，以及 (ii) 评估分蘖对生物量氮内部效率 (NIE)、谷物产量 (NIE) 的影响收获指数（HI）和氮收获指数（NHI）。在阿根廷布宜诺斯艾利斯，使用易分蘖玉米杂交种在不同种植季节（2017-2018 年和 2018-2019 年）进行了两次灌溉田间试验。处理是植物密度的组合[3个水平，4 p m = D4； 2 pl m = D2，包括在 D2、D2(-T) 的整个分蘖窗口期间进行额外的分蘖处理] 和两次土壤氮利用率 [未施肥 = 60 kg N ha 原生土壤 N (N-) 和施肥 = 220 kg N ha 原生土壤 + 施氮 (N+)]。在地上部（主地上部和分蘖）和作物水平上分析了生物量积累、氮吸收、HI、NHI、籽粒氮浓度 (GrainN%)、NIE 和 NIE。在使用 N+ 的 D2 中，分蘖作物比不分蘖作物具有更高的生物量和氮吸收量，但与 D4 相比并不能补偿密度的降低。分蘖的NIE与主枝相似，但分蘖的HI、NIE和NHI均低于主枝。主芽的作物 NIE 和 GrainN% 之间存在负相关关系，但由于这些次生芽的 HI 较低且可变，因此分蘖的关系不存在。在低密度玉米管理方案中，耕作者在资源丰富的季节增加资源捕获，通过持续的 NIE 产生更大的作物生物量。然而，与主芽相比，分蘖（和 NIE）固有的较低 HI 会降低分蘖作物的 NIE。关于分蘖对玉米作物氮经济影响的知识空白首次得到解答。新的问题出现了：比较主枝和分蘖的氮稀释曲线，量化开花后分蘖的氮吸收以及从分蘖到主枝的氮再利用。