نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی کارشناسی ارشد، گروه گیاهپزشکی، دانشکده کشاورزی، دانشگاه ایلام، ایلام، ایران
2 استادیار، گروه گیاهپزشکی، دانشکده کشاورزی، دانشگاه ایلام، ایلام، ایران
3 استادیار پژوهش، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی، شیراز، ایران
4 دانشجوی پسادکتری، گروه گیاهپزشکی، دانشکده کشاورزی، دانشگاه کردستان، سنندج، ایران
5 کارشناس، مدیریت حفظ نباتات، سازمان جهاد کشاورزی ایلام، ایلام، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction: Take-all disease, caused by the soil-borne fungus Gaeumannomyces graminis var. tritici, is among the most destructive diseases of wheat, causing root and crown rot that leads to whitehead symptoms and yield losses of up to 60%. Although conventional management strategies such as crop rotation and deep plowing offer partial control, their efficacy remains limited, while the extensive use of chemical fungicides has raised concerns regarding environmental pollution, fungicide resistance, and human health hazards. Consequently, plant essential oils, owing to their diverse bioactive constituents, have attracted increasing attention as eco-friendly alternatives for plant disease management. However, comparative studies evaluating the antifungal efficacy of ajwain, thyme, eucalyptus, and peppermint essential oils against the wheat take-all pathogen remain scarce. This study aimed to evaluate and compare the antifungal activity of these four essential oils against the mycelial growth of G. graminis var. tritici and to identify their chemical constituents.
Materials and Methods: Plant materials were collected from natural habitats in Ilam Province, Iran, and essential oils were extracted via hydrodistillation using a Clevenger-type apparatus. Pathogenicity of the fungal isolate (GenBank accession no. MH488732) was confirmed under greenhouse conditions according to Koch’s postulates. The antifungal activity of essential oils at concentrations of 0.4 to 1 µL/mL was assessed using the poisoned food technique in a completely randomized factorial design with three replications. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were determined for the two most effective oils (ajwain and thyme). Chemical constituents of ajwain and peppermint essential oils were identified via gas chromatography–mass spectrometry (GC-MS). Data were analyzed using SAS software, and means were compared by Duncan’s multiple range test at P < 0.05.
Resulta and Discussion: Analysis of variance revealed significant effects of essential oil type, concentration, and their interaction (P < 0.01) on fungal growth inhibition. Ajwain essential oil exhibited the strongest antifungal activity, achieving complete inhibition (100%) of mycelial growth at 1 µL/mL. Thyme essential oil ranked second, with a maximum inhibition of 86.30% at the same concentration. Eucalyptus and peppermint oils showed weaker inhibitory effects, with maximum inhibition rates of 75.76% and 53.43%, respectively. The MIC and MFC values were 1 and 1.2 µL/mL for ajwain, and 1.2 and 1.4 µL/mL for thyme, confirming the superior antifungal potency of ajwain oil. GC-MS analysis revealed thymol (66.91%) as the dominant compound in ajwain oil, accompanied by p-cymene and γ-terpinene, whereas peppermint oil was primarily composed of menthol (38.66%) and menthone (31.75%).
Conclusion: The findings demonstrate that the antifungal efficacy of plant essential oils is directly linked to the chemical nature of their dominant constituents. Essential oils rich in phenolic compounds, particularly thymol (ajwain and thyme), exhibited markedly higher antifungal potency compared to oils dominated by oxygenated monoterpenes (peppermint and eucalyptus) against G. graminis var. tritici. These results highlight the promising potential of ajwain and thyme essential oils as natural biocontrol agents for managing wheat take-all disease. Nevertheless, the volatile and unstable nature of essential oils may limit their direct field application; therefore, encapsulation technologies such as nanoencapsulation are recommended to enhance their stability, controlled release, and practical efficacy under field conditions.
کلیدواژه‌ها [English]
)