Background : Pachyrhizus erosus (Leguminosae), locally called as “Yam bean” is a traditional medical plant that grows in the tropical and subtropical region. The root of P. erosus is used by the local people to treat insomania, treatment of osteoporosis and extracts of this plant have shown antioxidant activity, immunomodulatory activity, tyrosinase inhibitionby, antitumour properties and cardiovascular benefit. Methods and Results : Free radical scavenging activity was evaluated using α-tocopherol and butylated hydroxy toluene (BHT) as standard antioxidants. The radical scavenging activity was measured using the stable radical 1,1-diphenyl–2-picrylhydrazyl (DPPH) and ABTS assay. Total phenolic content was determined by following Folin-Ciocalteau colorimetric method and Total flavonoids were determined using aluminium chloride calorimetric methods. Phenolic compound concentration and compositions were determined by HPLC-MS/MS system. Seedlings grown under the flourescent light (Fl) exhibited the highest DPPH radical scavenging activity when compared to the plants treated with light emitting diodes (LEDs) and light emitting plasma (LEP). LED-Blue showed the higher DPPH radical scavenging activity and ABTS concentration of PE compared to other LEDs. The accumulation of phenolic compounds increased under different white-LEDs conditions as compared to LEP and FL light conditions. Conclusion : In this study, antioxidant activity and phenolic compound composition of P. erosus was improved by the application of LED and LEP.