Essential oil composition, physiological and morphological variation in Salvia abrotanoides and S. yangii under drought stress and chitosan treatments

Several Salvia species are among the most valuable aromatic herbs used for industrial and pharmaceutical applications. Hence, under greenhouse trial conditions, the effects of chitosan treatment (0, 100, and 200 mg L−1) and water deficiency stress on the morphological, physiological, and biochemical features of two Salvia species were examined. Significant changes were seen in chlorophyll a, root volume, dry and fresh weight, and H2O2 concentration as a result of drought stress. Significant influence of chitosan was found for all studied parameters except root length and malondialdehyde (MDA) content. Hydrogen peroxide (H2O2), proline, and MDA were elevated, while photosynthetic pigments decreased under drought stress. The highest essential oil (EO) content (2.20% d.b.) was recorded under moderate stress condition in the absence of chitosan treatment. Using chitosan topically, it is possible to offset the impact of water scarcity on EO content decline and enhance EO compositions. The compensatory effects of chitosan application under stress conditions were observed on the abundance of EO constituents, such as 1,8-cineol, camphor, bornyl acetate, α-bisabolol, α-cadinol, and α-humulene. Moreover, present results suggested that chitosan application can alleviate the drought damage in studied Salvia species.