Essential oil analysis and phytotoxic activity of two ecotypes of Zataria multiflora Boiss. growing in Iran.

This study was conducted to assess the allelopathic effect of essential oils (EOs) obtained from the aerial parts of two different ecotypes (ECTPs A and B) of Zataria multiflora Boiss. with the aim of evaluating their in vitro germination and growth inhibition potential. Gas chromatography (GC) and GC-mass spectrometry (GC-MS) analysis of the oils revealed that carvacrol and linalool (77.4% and 90.6%) were the two major oil components in ECTPs A and B, respectively, which were regarded as two different chemotypes. Other important volatile compounds found in ECTP A were α-pinene (2.7%), p-cymene (7.9%) and γ-terpinene (3.5%). However, in ECTP B these compounds were in lesser amounts and γ-terpinene was not detected. The inhibitory effects of both EOs of ECTPs at concentrations of 0, 80, 160, 320 and 640 µL L⁻¹ on the seed germination and seedling growth of four noxious weeds were evaluated. A significant reduction (p ≤ 0.05) in germination rate, seedling length, root and stem fresh and dry weights were observed by ECTPs; the highest suppressing effect was observed at 320 and 640 µL L⁻¹. The results reported in this study suggest that herbicidal properties of the two ECTP oils could be attributed to their major components.