Abstract Crop mixtures may decrease reliance on pesticides but reducing herbicide use might increase weeds. Individual-based crop models can provide management guidelines. In heterogeneous canopies, light availability of individual plants depends on their dominant or dominated position. Estimating nitrogen demand at the plant scale, independently of light environment, is a challenge for modelling. A relationship linking shoot nitrogen amount to leaf biomass (or leaf area) at optimal nitrogen nutrition was investigated to establish if it could allow estimating nitrogen demand at the plant scale independently of its light environment. Crop and weed species were grown in greenhouse under various nitrogen treatments and, for two species, under two light levels. At the plant scale, shoot nitrogen amount was proportional to leaf biomass (or leaf area) at optimal nitrogen nutrition at vegetative stage. At reproductive stage, the relationship was allometric. The effect of light on shoot nitrogen amount per leaf biomass was minor and greater when using leaf area. Using data from previous experiments showed that the relationship using leaf biomass was stable across diverse growing conditions. The relationship linking shoot nitrogen amount to leaf biomass at optimal nitrogen nutrition can be used to model nitrogen demand of individual plants in heterogeneous canopies.

中文翻译：

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量化异质冠层中单个植物的氮需求：作物和杂草物种的案例研究

摘要 作物混合物可能会减少对农药的依赖，但减少除草剂的使用可能会增加杂草。基于个体的作物模型可以提供管理指南。在异质树冠中，单个植物的光照可用性取决于它们的优势或主导地位。独立于光环境估计工厂规模的氮需求是建模的一个挑战。研究了在最佳氮营养下将芽氮量与叶生物量（或叶面积）联系起来的关系，以确定它是否可以独立于光环境估计植物规模的氮需求。作物和杂草在温室中在各种氮处理下生长，对于两个物种，在两个光照水平下。在工厂规模上，在营养期最佳氮营养条件下，地上部氮量与叶片生物量（或叶片面积）成正比。在生殖阶段，这种关系是异速生长的。当使用叶面积时，光对每叶生物量的芽氮量的影响较小且较大。使用先前实验的数据表明，使用叶生物量的关系在不同的生长条件下是稳定的。在最佳氮营养条件下将芽氮量与叶片生物量联系起来的关系可用于模拟异质冠层中单个植物的氮需求。使用先前实验的数据表明，使用叶生物量的关系在不同的生长条件下是稳定的。在最佳氮营养条件下，将枝条氮量与叶片生物量联系起来的关系可用于模拟异质冠层中单个植物的氮需求。使用先前实验的数据表明，使用叶生物量的关系在不同的生长条件下是稳定的。在最佳氮营养条件下，将枝条氮量与叶片生物量联系起来的关系可用于模拟异质冠层中单个植物的氮需求。