Bioprospecting of Wild Botanicals against Alternaria Leaf Blight of Radish and their Phytochemical Profiling by GC-MS

Abstract

Abstract Cruciferous vegetables, globally important crops, face a severe threat from Alternaria blight, a pervasive and highly damaging disease, causing black spots and blight on leaves in field conditions, resulting in reduced yield and seed quality. The present study aims to evaluate the antifungal potential of different wild botanicals against the Alternaria leaf blight pathogen in in vitro and in vivo studies and to analyze the phytochemicals through Gas Chromatography Mass Spectrometry. Among fifty botanicals screened at a 10% concentration against the pathogen, the aqueous extracts of Hemidesmus indicus, Lippia alba, Chromolaena odorata, and Solanum violaceum displayed the highest mycelial inhibition. Further in vitro evaluations of these four botanicals at different concentrations (2.5%, 5.0%, 7.5%, 10.0%, and 12.5%) revealed that, at a 12.5% plant extract, H. indicus and L. alba exhibited the most effective inhibition of 82.96% and 76.60%, respectively, followed by C. odorata (71.93%) and S. violaceum (63.53%). Based on promising in vitro results, these botanicals were assessed in pot experiments at 12.5% concentration each. Among the four botanicals, the highest percentage of disease reduction was observed in H. indicus and L. alba, with 69.79% and 60.44%, respectively. Eventually, botanicals effectively reduced disease severity while increasing radish yield. GCMS analysis of phytochemicals revealed that botanicals often attributed to a combination of various bioactive compounds such as phenolics, flavonoids, saponins, and volatile compounds, known for their antimicrobial activities. This study emphasizes the potential of botanicals as a natural alternative for managing fungal diseases, offering resilient and sustainable approaches to safeguard crops from destructive fungal infections.