The present invention provides a method of reducing nitrate content in a plant by supplementing Rhodopseudomonas palustris DSM 29314 with a hydroponic nutrient solution, wherein the plant can grow in the hydroponic nutrient solution. The bacteria can effectively reduce 50% to 88% of the nitrate content in the plant, and only requires half concentration of the hydroponic nutrient solution than usual to enhance the fresh and dry weight of the plant up to 17% to 44%. It can effectively reduce cost, increase income and provide safe crops.
