Achieving successful outplanting of trees on increasingly harsher sites is a global concern. In Chile, for example, new Eucalyptus globulus plantations are being targeted to poorer, low fertility sites where additional stresses often negatively affect seedling performance during the first field season. Nitrogen-loading during the later stages of nursery production can, however, significantly improve seedling physiological performance on harsher sites by increasing plant growth and nutrient storage reserves for subsequent root growth after outplanting. Maximizing these benefits, and applying the concept of loading throughout the entire crop cycle, requires a better understanding of nitrogen (N) dynamics. Thus, for container E. globulus, considered one of the most important plantation species worldwide, we evaluated the effects of increasing N supply (50 to 600 mg N L⁻¹) on seedling morphological traits, biomass production, root growth potential, and foliar N. After 15 weeks of N application, seedlings showed an increase in all growth variables evaluated up to 300 mg N L⁻¹, whereas higher rates allowed luxury consumption. Modeling growth responses revealed, however, an apparent ammonium antagonism with other macronutrient cations suggests that high rates of this N-form may negate the potential benefits of N-loading, or that other modifications to the fertilizer solution may promote additional growth at higher N rates. Foliar N concentration, which was easily and accurately measured with a leaf chlorophyll meter, showed a gradient from basal to apical leaves suggesting a strong translocation of N in E. globulus seedlings. Our results suggest nursery management that supplies 300 mg L⁻¹ of N through the entire growing season could improve seedling nutritional status, morphological attributes, and growth of new roots, attributes that may improve establishment on low fertility sites.

在日益苛刻的地点成功移植树木是全球关注的问题。例如，在智利，新的桉树人工林的目标是较贫瘠，低肥力的地方，那里的附加压力通常会在田间第一个季节不利地影响幼苗的生长。然而，在苗圃生产的后期阶段，通过增加植株生长和移栽后随后根系生长所需的养分储备，氮肥可以显着改善在较苛刻部位的幼苗生理性能。要最大程度地发挥这些优势，并在整个作物周期中应用负荷概念，需要对氮（N）动力学有更好的了解。因此，对于容器E. globulus作为世界上最重要的人工林之一，我们评估了增加的氮供应量（50至600 mg N L ^-1）对幼苗形态性状，生物量生产，根系生长潜力和叶面氮的影响。施氮15周后，幼苗显示，评估至300 mg NL ^-1的所有生长变量均增加，而较高的价格则允许奢侈品消费。对生长反应的模型显示，但是，铵盐与其他大量养分阳离子的明显拮抗作用表明，这种高氮素形式的高比率可能抵消了氮素负荷的潜在益处，或者对肥料溶液的其他修饰可能会在高氮素比率下促进额外的生长。叶绿素浓度可以很容易地用叶绿素仪准确测量，显示从基生叶到根尖叶之间存在梯度，表明氮在大肠埃希氏菌幼苗中的转运很强。我们的结果表明提供300 mg L ^-1的苗圃管理 在整个生长季节中，N的施肥量可以改善幼苗的营养状况，形态特征和新根的生长，这些特征可以改善低肥力地区的立足点。