Oil cakes are agro-industrial wastes produced in large quantities, with still untapped potential in plant production. Basil is one of the most economical essential oil crops cultivated worldwide, requiring sustainable production methods. This greenhouse experiments evaluated the effects of flaxseed oil cake (FOC) added to peat substrate at the rates of 5, 10, and 20 g dm on herbal yield, content of bioactive compounds and mineral elements, antioxidant activity, and essential oil composition of basil ( 'Dark Opal'), grown under well-watered and drought stressed conditions. Two-way ANOVA, principal components analysis (PCA), and correlation networks were applied to associate the data. PCA analysis indicated variability in basil responses to the different treatments, with each treatment forming distinct clusters. The study revealed the beneficial effect of FOC on basil herb yield under water stress. Applying 10 g dm FOC was the most effective in mitigating drought stress in basil. Under drought stress conditions, FOC at the rate of 10 g dm increased fresh weight by 63.9 % and herb dry weight by 59.9 % compared with the peat-only substrate plants. As FOC rates increased, the nitrogen level of plant tissues and substrates increased while reducing sugars, total polyphenols, and total flavonoids content decreased. GC-MS analysis of basil essential oil showed that the main compounds were τ-cadinol (10.79–12.54 %), linalool (4.93–10.01 %), methyl eugenol (4.11–6.71 %), α-bergamotene (3.11–5.48 %) and eugenol (2.10–5.05 %). Drought stress lowed the linalool, methyl eugenol and α-bergamotene concentrations compared with the well-watered plants. However, adding FOC increased the accumulation of linalool and methyl eugenol in all of the FOC treatments under drought stress. Analysis of the differential network showed that the fresh and dry weight and the methyl-eugenol content as “hub” parameters correlated with most traits of basil grown under well-watered and drought stress conditions. In conclusion, using FOC at appropriate levels can effectively reduce plant herb yield loss caused by water stress.

中文翻译：

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亚麻籽油饼通过增加草本生物量和精油质量来提高干旱胁迫下罗勒 (Ocimum basilicum L.) 的产量


油饼是大量产生的农工业废物，在植物生产中仍有尚未开发的潜力。罗勒是世界范围内种植的最经济的精油作物之一，需要可持续的生产方法。该温室实验评估了以 5、10 和 20 g dm 的比例添加到泥炭基质中的亚麻籽油饼 (FOC) 对草药产量、生物活性化合物和矿物元素含量、抗氧化活性和罗勒精油成分的影响（“黑蛋白石”），在浇水良好和干旱的条件下生长。应用双向方差分析、主成分分析 (PCA) 和相关网络来关联数据。 PCA 分析表明罗勒对不同处理的反应存在差异，每种处理形成不同的簇。该研究揭示了 FOC 在水分胁迫下对罗勒草产量的有益影响。施用 10 g dm FOC 对于缓解罗勒的干旱胁迫最有效。在干旱胁迫条件下，与纯泥炭基质植物相比，10 g dm 的 FOC 使鲜重增加了 63.9%，草本干重增加了 59.9%。随着 FOC 速率的增加，植物组织和底物的氮含量增加，而还原糖、总多酚和总黄酮含量下降。罗勒精油的GC-MS分析表明，主要成分为τ-卡地醇（10.79-12.54%）、芳樟醇（4.93-10.01%）、甲基丁子香酚（4.11-6.71%）、α-香柠檬烯（3.11-5.48%）和丁子香酚（2.10–5.05%）。与浇水良好的植物相比，干旱胁迫降低了芳樟醇、甲基丁香酚和α-香柠檬烯的浓度。然而，在干旱胁迫下，所有 FOC 处理中添加 FOC 都增加了芳樟醇和甲基丁香酚的积累。 微分网络分析表明，鲜重、干重以及甲基丁香酚含量作为“中心”参数与在水分充足和干旱胁迫条件下生长的罗勒的大多数性状相关。总之，适量使用FOC可以有效减少水分胁迫造成的植物药草产量损失。