The benefit of seed priming in reducing germination time and improving emergence uniformity is well established under laboratory conditions. However, very few detailed studies have been conducted on the efficacy of activated seeds under field conditions. Previous work has shown that the success of seed activation is influenced by a complex interaction of factors including plant species, water potential of the activator, duration of activation, temperature, seed viability, and storage conditions of activated seeds.The present study has been planned to investigate the effect of halo priming on growth, nutrient, biochemical parameters and enzyme activity in tomato seedlings under salinity conditions.