BACKGROUND Amaranth leaves can provide important nutrients to small-scale farming families growing amaranth for seed. Amaranth is known to be tolerant to defoliation, but there is little guidance on when defoliation should be performed for optimal nutritional benefits. This series of experiments assessed tolerance to defoliation at different points throughout the vegetative stage of development, in addition to the nutritional benefits and flavor of amaranth leaves at each stage. RESULTS Overall, timing of defoliation had no impact on seed yield or quality. 50% defoliation at any point did not significantly reduce seed yield, whereas 100% defoliation throughout development reduced seed yield. The nutritional value of amaranth leaves differed substantially throughout development, with the highest concentrations of iron mid-way through vegetative development, and the highest levels of vitamin A, magnesium and copper at the end of the vegetative development stage. Palatability was highest in young leaves, and decreased as plants aged. We also found that neither timing nor intensity of defoliation had an influence on branching, which can negatively influence ease of harvest. CONCLUSIONS These results indicate that amaranth leaves are a nutritious food source that provides vital nutrients at different concentrations throughout development. Farmers who wish to harvest both leaves and seeds can harvest up to 50% of the leaves at any point during vegetative development or bud formation while maintaining seed yield. Leaf harvest timing can thus be tailored to nutritional needs, though palatability decreases with plant age. This article is protected by copyright. All rights reserved.

中文翻译：

---

两用苋菜生产系统中最佳叶片营养的落叶时机

背景苋菜叶可为种植苋菜种子的小规模农户提供重要的营养。众所周知，苋菜可以耐受落叶，但很少有关于何时进行落叶以获得最佳营养益处的指导。除了每个阶段苋菜叶的营养价值和风味外，这一系列实验还评估了整个营养发育阶段不同时间点的落叶耐受性。结果 总体而言，落叶时间对种子产量或质量没有影响。任何时候的 50% 落叶都不会显着降低种子产量，而整个发育过程中的 100% 落叶会降低种子产量。苋菜叶的营养价值在整个发育过程中差异很大，营养发育中期的铁含量最高，而营养发育后期的维生素 A、镁和铜含量最高。适口性在幼叶中最高，随着植物老化而降低。我们还发现，落叶的时间和强度都不会影响分枝，这会对收获的难易产生负面影响。结论 这些结果表明，苋菜叶是一种营养丰富的食物来源，可在整个发育过程中提供不同浓度的重要营养素。希望收获叶子和种子的农民可以在营养发育或芽形成期间的任何时候收获多达 50% 的叶子，同时保持种子产量。因此，可以根据营养需求调整叶子的收获时间，但适口性会随着植物年龄的增长而降低。本文受版权保护。版权所有。