Secondary Metabolites and Biological Activities From <i>Achillea gypsicola</i> Hub-Mor. Under Foliar Applications of Chitosan and Salicylic Acid

Elicitors play a crucial role in plant defense systems, often leading to an enhancement in secondary compounds across various species. The aim of this paper was to assess the effect of elicitors of salicylic acid (SA) and chitosan (CTS) applied to the leaves on essential oil (EO) composition of Achillea gypsicola and some terpenoids and biological activity. Treatments with SA at doses of 0, 0.5, 2, and 8 mM, and CTS at 0, 2, 4, and 8 g L-1 were evaluated. Two harvests were conducted between 2021 and 2022. Elicitors SA at 8 mM and CTS at 2 g L-1 led to an increase in EO productivity. The application of elicitors, particularly at doses of 2 mM SA and 4 g L-1 CTS in A. gypsicola, has the potential to stimulate camphor production. Additionally, TPC and TFC were the highest in treatments of SA 2 mM and CTS 8 g L-1. LC-MS/MS analysis indicated that the synthesis of camphor and 1,8-cineole enhanced significantly compared to the control group, with enhancements of 213.2% at 8 g L-1 CTS and 125.1% at 4 g L-1 CTS, respectively. The EOs are especially effective against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Listeria monocytogenes.