Eco-friendly preparation of thyme essential oil nano emulsion: Characterization, antifungal activity and resistance of Fusarium wilt disease of Foeniculum vulgare

Abstract

Essential oil nanoemulsions have received much attention in the last period for controlling of fungal plant pathogens. In this study, thyme oil nanoemulsion (TONE) was successfully prepared from thyme oil which extracted from Thymus vulgaris (T. vulgaris). The prepared TONE was characterized using DLS, Zeta potential, and TEM analyses. Results revealed that, TONE has spherical shape with size 32.7 nm. Moreover, results illustrated that TONE exhibited promising antifungal activity against Fusarium oxysporum (F. oxysporum) with minimum fungicidal concentration (MFC) 5 mg/ml. Additionally, TONE concentrations 1, 2, 3 and 4 mg/ml reduced the growth of F. oxysporum with percentages 7.78, 31.1, 52.2 and 67.8 % respectively. Disease index (DI) of Fusarium wilt reached the maximum rate by (85 %) in the Foeniculum vulgare (F. vulgare) plant infected with F. oxysporum. Application of TONE treatment on infected plants led to a decrease in DI to (17.5%) and an increase in the percentage of protection to (79.4%). Furthermore, DI was decrease to 42.5% with protection percentage 50% in the case of infected plant with TOE.  Moreover, TOE, TONE played an important role in improving plant immunity by increasing phenol, proline, and antioxidant enzymes (POD&PPO) activities, as well as reducing oxidative stress by reducing (MDA & H2O2). Results revealed that TONE led to significant increase in free proline in compared to TOE. We can conclude that TOE, TONE are considered eco-friendly safe strong inducers of F. vulgare plant immunity alternatives to difenoconazole against fusarial wilt disease to preserve plant, soil, and human health.