The current investigation aimed to ascertain how Argemone mexicana L. affected Vigna Mungo protein content, photosynthetic pigments, seed germination, and seedling growth in an allelopathic manner. The most significant edible crop is the black gram. Though it may grow in various soil types and temperatures, black gram is most successful in humid areas with 30-90 cm of precipitation. Argemone mexicana L. is a marijuana cultivator that is increasing and is a significant competitor to the black gram in terms of allelochemicals. One of the main factors reducing crop productivity is weeds. After harvesting and washing them with tap water to remove dirt particles, the complete Argemone mexicana L. plant was dried in the shade and maintained at 25°C (±2) for 72 hours. To illustrate the germination of locally cultivated Black gram seeds, four concentrations of varying ratios of aqueous extract were prepared. A bioassay experiment evaluated Argemone mexicana L. allelopathic capacity on Black gram seed germination. Weed extracts diluted with water were employed as a therapy. A pronounced inhibitory action of Argemone mexicana L. was noted on Black gram.