Oregano, Origanum vulgare L., is a well-reputed medicinal herb used globally in cosmetics, food and pharmaceutical industries. Essential oil (EO) composition and productivity of oregano subspecies are highly affected by water deficit stress. Here, a two-year (2018 and 2019) greenhouse study was conducted to comparatively investigate the impact of water deficit stress on biochemical traits and EO profiles of two carvacrol-rich subspecies of O. vulgare (subsp. gracile and subsp. hirtum). The pot-grown plants were subjected to four water stress treatments based on field capacity (FC) method, i.e., control condition (100 % FC), mild stress (75 % FC), moderate stress (50 % FC) and severe stress (35 % FC). Overall, the EO content of subsp. hirtum (up to 3.25 % (v/w)) was higher than that of subsp. gracile (up to 1.92 % (v/w)). Compared with control, the EO contents increased by over 75 % under moderate water stress. Carvacrol was present in the EO profiles of both subspecies as the major component. Its highest content in the subsp. hirtum was achieved under mild water stress (i.e., 60 % (in 2018) and 68 % (in 2019)), whereas in the subsp. gracile, it was obtained under severe (55 % (in 2018)) and moderate (51 % (2019)) stresses. Overall, the subsp. hirtum showed higher dry weight, EO and carvacrol content than subsp. gracile. Furthermore, a significant positive correlation was observed among dry weight and EO content (r = 0.74, p < 0.01). On the other hand, there was a negative correlation between carvacrol and p-cymene content (r = −0.60, p < 0.01). Water stress treatments inevitably reduced fresh weight, dry weight, relative water content and total chlorophyll content in both subspecies. However, the maximum quantum yield of PSII (Fv/Fm), superoxide dismutase and ascorbate peroxidase activity, and also proline content was changed in a subspecies-specific manner. The results of the present study enabled selection of the subsp. hirtum as a desirable prototype for relevant cultivation and prospective breeding programs.

牛至，牛至属植物，是一种广受赞誉的药用草药，在全球化妆品，食品和制药行业中广泛使用。牛至亚种的精油（EO）组成和生产力受缺水压力的严重影响。在这里，一个为期两年（2018年至2019年）的温室研究，以比较进行调查缺水胁迫对生化性状和两个富香芹酚，亚种的EO特征的影响O.大麦（亚种竹叶和亚种。hirtum）。对盆栽植物进行了基于田间持水量（FC）方法的四种水分胁迫处理，即控制条件（100％FC），轻度胁迫（75％FC），中度胁迫（50％FC）和重度胁迫（ 35％FC）。总体而言，子空间的EO含量。hirtum（高达3.25％（v / w））高于亚种。轻巧（高达1.92％（v / w））。与对照相比，在适度的水分胁迫下，EO含量增加了75％以上。香芹酚作为主要成分存在于两个亚种的EO谱中。它在子空间中的最高内容。hirtum是在轻度水分胁迫下实现的（即60％（2018年）和68％（2019年）），而在亚种中。轻柔的，它是在严重（55％（2018年））和中等（51％（2019年））压力下获得的。总体而言，subsp。hirtum的干重，EO和香芹酚含量高于亚种。轻柔的。此外，在干重和EO含量之间观察到显着的正相关（r = 0.74，p <0.01）。另一方面，香芹酚与p-肉桂精含量之间呈负相关（r = -0.60，p<0.01）。水分胁迫处理不可避免地降低了两个亚种的鲜重，干重，相对水含量和总叶绿素含量。但是，PSII的最大量子产率（Fv / Fm），超氧化物歧化酶和抗坏血酸过氧化物酶活性以及脯氨酸含量也以亚种特异性方式改变。本研究的结果使得能够选择亚种。hirtum是相关栽培和预期育种计划的理想原型。