Abstract
•Rhizoctonia solani causes damping off disease of common bean.•Vitex agnus-castus essential oils caused a significant decrease in growth of R. solani.•Foliar spray with 50 ppm ZnO NPs used also in controlling disease.•Dual treatment caused a reduction of disease incidence and enhance the seed germination.•Eco-friendly dual treatment could alert common bean resistance to damping off disease.
This study was conducted to find an alternative to synthetic fungicides currently used in the control of Rhizoctonia solani damping off in common bean (Phaseolus vulgaris L.). The efficacy of seed presoaking in Vitex agnus-castus essential oils and foliar sprays with 50 ppm ZnO NPs in controlling the pathogen was evaluated under greenhouse conditions. The minimum inhibitory concentration of V. agnus-castus essential oils (400 μl/L) caused a significant decrease in mycelial growth and the productivity of cell wall degrading enzymes (CWDEs) of R. solani in vitro test. And also, Polygalacturonase, polymethyl-galacturonase, endoglucanase and β-glucosidase retained only about of its relative enzyme activities 10.5, 14.9, 8.8, 0%, respectively. The combination between seed presoaking in Vitex agnus-castus essential oils and foliar spray with ZnO NPs was found to be more effectivethan each of them separately, in reduction of disease incidence and enhance the seed germination percentage from 62% in infected untreated plants to 87% in infected plants exposed to dual treatment. Our results revealed that the content of enzymatic antioxidants (catalase, peroxidase, polyphenol oxidase and superoxide dismutase), non-enzymatic antioxidants (glutathione, anthocyanin and ascorbic acid), total flavonoids, total phenolics, tannins, proline, glycine betaine, ferric reducing antioxidant power, total antioxidant capacity and mineral composition (potassium, nitrogen, phosphorus, calcium and zinc) were significantly higher in the infected plants received the dual treatment as compared with the untreated infected plants. Moreover, CWDEs, H2O2 content and lipid peroxidation significantly decreased in infected plants received the dual treatment as compared with the untreated infected plants.