Abstract
Wild radish is increasingly becoming a problematic and troublesome weed of cropping systems in Pakistan, and an environment-friendly solution for this rapidly spreading weed is inevitable. The aqueous extracts of herbal plants with a strong phytotoxic influence are supposed to be used for an eco-friendly management of this weed. So, various pharmaceutical plants locally available in Pakistan were explored for their allelopathic potential against seed germination and seedling growth of wild radish. In this regard, aqueous extracts of the Swertia chirata L., Citrullus colocynthis L., Populous trmuloides L., Aloe barbadensis miller L., Fumaria officinalis L., Sphaeranthus indicus L., Berberis aristata L., and Withania coagulans L. were prepared, and their phenolic compounds were identified. The aqueous solution of Sphaeranthus indicus L. showed a maximum decline in germination percentage (76%), germination index (62%), and germination energy (76%), causing a maximum delay (3 days) to complete 50% germination with the highest mean germination time (4.6 days) of wild radish as compared with distilled water treatment. The shoot length, root length, shoots dry weight, root dry weight, seedling biomass and seedling vigor index of wild radish were most inhibited by aqueous solutions of Citrullus colocynthis L. The highest electrolyte leakage of wild radish seedlings was also observed where aqueous extracts of Citrullus colocynthis L. were applied. The leachate of Aloe barbadensis miller L. was the second most inhibitor of germination and seedling growth of wild radish. The Populous trmuloides L. also ranked second regarding germination inhibition. In contrast, the aqueous extracts of Swertia chirata L. and Berberis aristata L. showed a reverse phenomenon and enhanced the germination. The Aqueous extracts of all other plants showed marginal results regarding germination and seedling growth inhibition and were statistically at par with control treatment. Furthermore, the highest concentration of phenolics was detected in Sphaeranthus indicus L. (2789 mg L-1), while the lowest was present in Withania coagulans L. (1093 mg L-1).