Abstract Brassinosteroids may importantly affect safflower (Carthamus tinctorius L.) growthand quality under stress. The oil responses of three spring safflower genotypes (Goldasht, Faraman and Sina) affected by the exogenous application of 24- epibrassinolide (EBL, 0.1 μM) under drought stress (85 (I1), 65 (I2) and 45 % (I3) of the field capacity) were investigated in 2016. The stress decreased oil percentage and yield, fatty acid yield and stomatal conductance, whereas supplying sufficient water did not alter fatty acid content. EBL increased oil and fatty acid percentage (except palmitic acid), and stomatal conductance. Foliar EBL application led to enhancement of oleic (15.95 %), linolenic (22.50 %), linoleic (4.26 %) and stearic acid (29.6 %) compared with control. The hormonal treatment also enhanced oil and fatty acid yield in I1 and I2. The desaturation efficiency and unsaturation indexes indicated that EBL can affect safflower response under the stress by desaturating 18:2 fatty acids to 18:3 fatty acids. Safflower oil content and fatty acids, as a function of plant genotype, can be enhanced under drought stress using EBL. The presented research can also further enhance our understanding related to lipid metabolism in safflower affected by EBL under drought stress. Such results are of nutritional, economic, industrial and environmental significance.

中文翻译：

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24-表油菜素内酯对干旱胁迫下红花籽油含量和脂肪酸组成的缓解作用

摘要 油菜素类固醇对胁迫下红花（Carthamus tinctorius L.）的生长和品质有重要影响。外源施用 24-表油菜素内酯（EBL，0.1 μM）对干旱胁迫（85 (I1)、65 (I2) 和 45% (I3)田容量）在 2016 年进行了调查。压力降低了油百分比和产量、脂肪酸产量和气孔导度，而提供足够的水并没有改变脂肪酸含量。EBL 增加了油和脂肪酸百分比（棕榈酸除外）和气孔导度。与对照相比，叶面 EBL 施用导致油酸 (15.95%)、亚麻酸 (22.50%)、亚油酸 (4.26%) 和硬脂酸 (29.6%) 的增加。激素处理还提高了 I1 和 I2 的油和脂肪酸产量。去饱和效率和不饱和指数表明EBL可以通过将18:2脂肪酸去饱和至18:3脂肪酸来影响胁迫下的红花响应。红花油含量和脂肪酸作为植物基因型的函数，可以在干旱胁迫下使用 EBL 提高。所呈现的研究还可以进一步增强我们对干旱胁迫下受 EBL 影响的红花脂质代谢的理解。这些结果具有营养、经济、工业和环境意义。所呈现的研究还可以进一步增强我们对干旱胁迫下受 EBL 影响的红花脂质代谢的理解。这些结果具有营养、经济、工业和环境意义。所呈现的研究还可以进一步增强我们对干旱胁迫下受 EBL 影响的红花脂质代谢的理解。这些结果具有营养、经济、工业和环境意义。