Evaluation of Various Biostimulant Applications on Growth, Physiology, and Secondary Metabolites of Satureja hortensis under Saline Conditions

Salinity is a major abiotic constraint adversely affecting plant growth, metabolism, and secondary metabolite biosynthesis, particularly in medicinal and aromatic species. This study was conducted under controlled greenhouse conditions in ۲۰۲۴ in Ilam, Iran to investigate the ameliorative effects of selected biostimulants on Satureja hortensis L. exposed to salinity stress. The experimental design was factorial based on a completely randomized design with three salinity levels (۰, ۵۰, and ۱۰۰ mM NaCl) and five foliar-applied treatments: distilled water (control), methyl jasmonate (۵۰ μM), salicylic acid (۱ mM), gamma-aminobutyric acid (GABA, ۲۰ mM), and glycine betaine (۵ mM). The results revealed that salinity significantly impaired chlorophyll content, shoot dry biomass, and essential oil accumulation, while increasing hydrogen peroxide levels as a marker of oxidative stress. However, the exogenous application of biostimulants, particularly GABA, substantially mitigated the negative impacts of salt stress. GABA foliar treatment not only enhanced the accumulation of chlorophylls, soluble carbohydrates, and proline, but also markedly reduced hydrogen peroxide content. Under moderate salinity, GABA application led to the highest essential oil content (۲۱۸% increase compared to the untreated control), while under non-saline conditions it resulted in the greatest shoot dry biomass (۱۰۳% higher than under severe salinity without biostimulant). Collectively, the findings highlight the promising role of GABA as a cost-effective, eco-friendly, and physiologically active bioregulator for improving salt stress tolerance and enhancing the phytochemical and agronomic performance of medicinal plants.

کلیدواژه ها:

Biostimulants ، Chlorophylls ، Essential oil content ، Food security ، Oxidative stress