Induction of Resistance and Defense Mechanisms of Geranium Plants Against Root Rot Disease Using Gallic Acid and 3,5-dinitrobenzoic Acid.

Root rot is a serious disease, causing considerable losses in essential oil production every year. In addition, the time of planting has a substantial impact on the severity and rate of disease development, combining the best strategies for applying exogenous polyphenolic compounds, plays a critical role in lowering disease-induced oxidative stress. This study focused on the role of gallic acid (GA) or 3,5-dinitro benzoic acid (3,5-DNBNZA) acid in regulating resistance against geranium root rot pathogens i.e., Fusarium semitectum, Macrophomina phaseolina, Pythium irregulare, and Rhizoctonia solani via a multifunctional defense system. GA (600 mgL-1) and 3, 5-DNBZA (300 mgL-1) showed optimal antifungal activity by affecting the pathogen's cell wall integrity and capacity to produce oxidative enzymes at various levels in vitro. The pathogens' mixture has a synergistic action since the infection percentages significantly increased than each pathogen alone in the pathogenicity test. The quadratic regression analysis confirmed that the disease incidence (%) gradually increased from winter to summer season. The dual application approach of GA or 3, 5-DNBZA was superior to the single application method for protection against root rot incidence and disease severity, coinciding with delaying the symptoms, improving the plant biomass and oil yield. Along with their favorable effects on biochemical traits, defense phenolics, enzymatic activities, and reduced leaf senescence. The present study recommended the dual application of GA or 3, 5-DNBZA as a sustainable and safe alternative management strategy for root rot disease and enhanced oil production. Also, elucidate the physiological and biochemical mechanisms behind their protective role.