Vigna mungo L. (black gram) is a summer pulse crop endemic to Central Asia. It is one of Pakistan's top five premium food beans and a highly cost-effective crop. Allelochemicals in Trianthema portulacastrum L. (black pigweed) leaf extract decreased the V. mungo germination rate (34% to 6%), seedling length (10 cm to 3 cm), fresh biomass of seedling (2.4 g to 0.94 g) and dry biomass of seedling (1.2 g to 0.47 g). Biological agent Pseudomonas sp. (PF-097) act as bioherbicide and as plant growth promoter agent to decrease the T. portulacastrum allelopathic stress and to enhance the growth of V. mungo. Amendment of Pseudomonas sp. (PF-097) increase V. mungo percentage of germination (8-42%), seedling length (12-54%), fresh biomass of seedling (8-17%) and dry biomass of seedling (0.47 g to 1.2 g). In vivo pot experiment bioassay revealed that of T. portulaacstrum significantly suppress the shoot length (46 cm to 18 cm), shoot fresh biomass (2.6 g to 0.66 g) and shoot dry biomass of V. mungo (1.31 g to 0.33 g). Pseudomonas sp. (PF-097) PGPR incorporation in vivo experiment significantly increased the shoot length (4% to 12%), shoot fresh biomass (18% to 35%), shoot dry biomass of V. mungo (17% to 35%). Physiological activity of Catalase and peroxidase considerably increased in negative treatments amended with only T. portulacastrum and decreased in positive treatments by using biological agent Pseudomonas sp. (PF-097). Protein content of V. mungo seedling was significantly increased in positive treatments as compared to negative treatments. These results showed that allelochemical stress of T. portulacastrum on the V. mungo can be countered by the herbicidal activity of the Pseudomonas sp. (PF-097).