Release of heavy metal pollutants in soil is major threat to environment and crops. Heavy Metal pollu-tant, hexavalent chromium released due to anthropogenic activities effects, growth metabolism and enzymes of ni-trogen metabolism in oil seed crop Helianthus annuus, after entering its to plant system. Chromium (VI) ranging from 0, 10, 20, 50, 100 and 200 mg kg-1soil mixture was provided to plants of three varieties of sun flower and activi-ty of glutamine synthetase and glutamate synthase enzymes was observed in leaves of mature plants. It was observed that even at the highest concentration of chromium, the enzyme activity was reduced by only 17.65 % and 18.22 % showing that glutamine synthetase activity was showing that glutamine synthetase activity was insensitive to chro-mium in all these varieties of plants. For glutamate synthase enzyme, the low chromium concentration of 10 and 20 mg kg-1soil was favourable but high chromium IV concentration of 50, 100 and 200mg kg-1soil was adversely af-fecting the glutamate synthase activity in all the three verities of sunflower.