The effect of ammonium nitrate (NH ₄NO ₃) on shoot bud induction and proliferation from nodal explants of Dianthus caryophyllus L. was investigated. Shoot buds were induced on MS medium supplemented with 2.2µM BAP and 2.7µM NAA. The induced shoot buds were sub-cultured on medium with same hormonal composition for their proliferation. Both shoot bud induction and proliferation media were supplemented with different levels of NH ₄NO ₃ ( 0, 5.15, 10.3, 20.61*, 41.20 mM ). NH ₄NO ₃ highly influenced the shoot bud formation and their subsequent proliferation. In the present investigation, NH ₄NO ₃ at one-fouth of MS level was found to be beneficial for controlling the hyperhydricity of regenerated shoots whereas the number of shoots was comparable to the control cultures. The MS or higher levels of NH ₄NO ₃ were observed to suppress healthy morphogenesis and resulted in increased hyperhydricity. The physiological disorder of hyperhydricity, commonly observed in carnation micropropagation, was also controlled with 100 % efficiency by reducing NH ₄NO ₃ at one-fouth of MS level. Antioxidant enzyme activity was minimum in normal and healthy shoots. The activity increased with increase in the number of hyperhydric shoots.