Yield and Essential Oil Accumulation of Stachys setifera Linked to Aerenchyma Development

Abstract This study examined the effects of self- and cross-pollination on agro-morphological traits, aerenchyma formation, and essential oil composition in Stachys setifera C.A.Mey. Ten clonally propagated genotypes and their seed progenies were evaluated over two years under greenhouse and field conditions. Significant genetic variation was detected among genotypes for biomass, seed yield, and essential oil content. Self-pollination led to contrasting effects: it enhanced traits such as hundred-seed weight and essential oil content in some genotypes, while causing inbreeding depression in wet and dry weight or seed number in others. GC–MS analysis identified 15 essential oil compounds, with geraniol, linalool, hexadecenoic acid, tetradecanoic acid, and geranyl acetate as the dominant constituents. Inbreeding differentially influenced these compounds, indicating both enhancement and reduction across genotypes. Aerenchyma traits were significantly higher in parents than progenies, and correlation and multivariate analyses revealed strong associations between root and rhizome aerenchyma with yield components and essential oil content. Genotypes with higher oil content and yield such as Rahnan, Ji Shir, Rodehen, and Dastgerd were identified for high biomass and essential oil production. Given the crucial role of aerenchyma in vegetative storage and reproduction through facilitating gas exchange with the rhizosphere, an increase in its area and number appears to directly enhance the medicinal potential of S. setifera .