Water scarcity has widely affected agricultural production and food security, particularly in arid regions. There is little information available on the concurrent effects of water stress and organic amendment application on the water holding capacity of soil as well as the growth and yield responses of quinoa as a drought-resistant plant. In addition, there are limited reports on the optimum levels of deficit irrigation as a promising strategy for enhancing the water use efficiency and production of quinoa plant. Therefore, the aim of this study is to investigate the moisture holding capacity of soil as well as the morphological and physiological responses of quinoa to the interactive effects of drought and organic amendment under field conditions. Three levels of water stress (full-irrigation, moderate drought, and severe drought) and four treatments of organic amendment including control (without the use of organic matter), vermicompost (20 t ha⁻¹), biochar (20 t ha⁻¹), and the composition of vermicompost and biochar (at an equal rate of 10 t ha⁻¹ each) were applied as the subsidiary factor. Result indicated that severe drought reduced the plant yield significantly (21.7%) as compared to control, whereas moderate drought showed no significant effect. Drought increased the proline content, whereas reduced all other traits including crop growth rate, 1000-seeds weight, bush height, panicle length, leaf area index, chlorophyll, proline, carotenoids, protein, and relative water content. However, the application of biochar, vermicompost, and Bvrm relative to the control treatment increased WUE by 12.3, 36.8, and 45.6%, soil moisture content by 2.0, 20.1 and 28.9%, and the quinoa yield by 1.0, 21.9, and 28.6%, respectively. There was an inverse relationship between water use efficiency and the grain yield of quinoa. The simultaneous effect of drought and biofertilizer on the quinoa grain yield (Y) was demonstrated based on soil moisture content (θ) using a linear relationship (Y = 168.5(θ) − 4.74; R² = 0.994, p < 0.01). The results also indicated that WUE was reduced linearly with increasing soil moisture content. Among different relationships, logarithmic function exhibited the best performance for predicting the yield of quinoa based on the amount of irrigation water. The findings of this study revealed the important role of soil moisture as a manageable characteristic in facing environmental stresses such as drought and achieving the sustainability of crop production.

水资源短缺广泛影响农业生产和粮食安全，特别是在干旱地区。关于水分胁迫和有机改良剂应用对土壤持水能力的同时影响以及藜麦作为抗旱植物的生长和产量反应的信息很少。此外，关于赤字灌溉的最佳水平作为提高藜麦植物用水效率和产量的有前途的策略的报道有限。因此，本研究的目的是研究田间条件下土壤的持水能力以及藜麦对干旱和有机改良剂相互作用的影响的形态和生理反应。三个级别的水分胁迫（完全灌溉、中度干旱和严重干旱）和四种有机改良处理，包括对照（不使用有机物）、蚯蚓堆肥（20 t ha -1 ）、生物炭（20 ^t ha ^{-1 ），蚯蚓粪和生物炭的成分（各10 t ha -1}的相同比例）被用作辅助因素。结果表明，与对照相比，严重干旱使植物产量显着降低（21.7%），而中度干旱则没有显着影响。干旱增加了脯氨酸含量，而降低了所有其他性状，包括作物生长率、千粒重、灌木高度、穗长、叶面积指数、叶绿素、脯氨酸、类胡萝卜素、蛋白质和相对含水量。然而，与对照处理相比，施用生物炭、蚯蚓粪和Bvrm使WUE分别提高了12.3%、36.8%和45.6%，土壤含水量提高了2.0%、20.1%和28.9%，藜麦产量提高了1.0%、21.9%和28.6% ， 分别。水分利用效率与藜麦产量之间存在反比关系。基于土壤水分含量（θ），使用线性关系（Y = 168.5（θ）− 4.74；R 2 = 0.994，p < 0.01）证明了干旱和生物 肥料对藜麦^籽粒 产量（  Y）的同时影响。结果还表明，WUE 随着土壤含水量的增加而线性降低。在不同的关系中，对数函数在根据灌溉水量预测藜麦产量方面表现出最佳性能。这项研究的结果揭示了土壤湿度作为一种可管理的特性在应对干旱等环境压力和实现作物生产的可持续性方面的重要作用。