Effects of Irrigation and Drought on Growth and Essential Oil Production in <i>O. vulgare</i> and <i>R. officinalis</i>

Abstract

The essential oil industry has led a rapidly growing market in American herbal medicine. The global essential oil industry was valued at an estimated 18.6 billion USD in 2020 and is expected to have a compound annual growth rate of 7.6% from 2020 to 2027. “Essential oil” is a broad term used to describe volatile organic compounds (VOCs) that are often associated with a plant’s essence or aroma. These molecules are commonly extracted from a variety of different plant structures by steam distillation and cold pressing. Essential oils function as a defense against insects, bacteria, fungi, and other stressors, such as drought and cold. The most industrially important of this class of compounds are monoterpenes, steam-volatile constituents which are the most abundant terpenes throughout plants. Essential oils may include monoterpenes (two isoprene units), sesquiterpenes (three isoprene units), ketones, and phenolics. Phenolics include flavonoids, anthocyanins, and tannins.