Investigating the crucial role of salicylic acid and harvest time on the yield and essential oil composition in sage (Salvia officinalis L.)

This research was carried out to determine the effects of different harvest time (HT) and salicylic acid application (SAA) on agronomic and quality characteristics of sage. The experiment was carried out in a randomized complete block design in split plots with HTs (pre-flowering and 50% flowering periods) in the main plots and SAAs in the subplots (Control, 1, 2, and 4 mM). Plant height, fresh herb yield, dry herb yield, fresh leaf yield, dry leaf yield, leaf ratio, essential oil (EO) content, EO yield, and EO composition were examined. In total or mean results, the HT was statistically significant on plant height, fresh and dry herb yield, leaf ratio in both years. The SAA was statistically significant on fresh and dry herb yield and leaf ratio only in the second year. Among the 24 components identified, alpha thujone was the main component. This component was followed by camphor, 13-epimanool, veridiflorol, 1.8-cineol. According to the principal component analysis (PCA), in 2021, 1 mM SAAs applied at the 50% flowering period in the first cutting and at the pre-flowering period in the second cutting showed different properties regarding EO composition. In 2022, 4 mM SAAs applied at the 50% flowering period in the first and second cuttings showed different properties regarding EO composition. The study found that delaying the HT led to significant increases in plant height, fresh and dry herb yields. Additionally, the SAA increased the herb yield and decreased the leaf ratio, particularly in the second year.