Mung bean (Vigna radiata L. wilezek) is an important food legume which belongs to the family, Fabaceae (Leguminaceae) and sub family Papilionaceae is extensively grown in humid to arid and semi-arid regions. The ability of Rhizobium bacteria to fix nitrogen from the air (N2) in symbiosis with legumes, huge natural source of nitrogen from the air can be taken up from this symbiotic association. This ability leads to decrease or absence of nitrogen mineral fertilizer application in the field. Therefore, there is need to explore the potential of rhizobia as legume inoculants under agro climatic conditions. Foliar application of NAA is able to control flower drop and improve the flower and fruit setting, nodulation, number of pods per plant, seed yield and harvest index in mungbean with the inoculation of Rhizobium along with NPK application. Inspite of growth regulators spray of certain chemical like potassium nitrate has been reported to play significant role in sources-sink relationship and ultimately increase the harvest index.