Evaluation of essential and nanoemulsion oils for suppressing damping-off and white stem rot diseases in chickpea plants

Abstract

Sclerotinia sclerotiorum (Lib.) de Bary is a major soil-borne fungal pathogen responsible for damping-off and stem rot diseases of chickpea (Cicer arietinum L.). The three essential and nanoemulsion oils of marjoram, basil, and lemon were assessed both in vitro and in vivo to suppress S. sclerotiorum pathogenic fungus. In the in vitro study, the most significant inhibitory effect on S. sclerotiorum growth was observed with lemon nanoemulsion and essential oil, followed by basil and marjoram nanoemulsion and essential oil, respectively.The ultrathin section of S. sclerotium, treated with either lemon essential oil or nanoemulsion oil, was examined using transmission electron microscopy and exhibited notable alterations in several cellular components, including the nucleus, mitochondria, vacuole size, and hyphal cell wall. All tested essential oils and nanoemulsion oils significantly reduced the incidence of chickpea damping-off and stem rot disease caused by S. sclerotiorum, in addition to the fungicide Topsin M-70®, both in greenhouse and field conditions during the 2021/2022 and 2022/2023 growing seasons. Topsin M-70® emerged as the most effective treatment, followed by lemon and basil nanoemulsion oils, with the lowest disease incidence and the highest percentage of surviving plants. All these treatments showed a significant increase in enzyme activity (peroxidase, polyphenol oxidase, catalase, and β-1,3 glucanase) and phenolic content in chickpea plants compared to the control plants. In the field study, all the treatments of the checked essential and nanoemulsion oils and Topsin M-70® showed significantly increased chickpea growth and yield parameters during the two growing seasons.