Nitrogen metabolism as affected by hexavalent chromium in sorghum ( Sorghum bicolor L.)

Abstract

A pot experiment was conducted to determine the effects of varying Cr (VI) levels (0–4 ppm in the form of potassium dichromate) on the key enzymes of nitrogen metabolism in sorghum. Total as well as specific enzyme activity of nitrate reductase, nitrite reductase, glutamine synthetase, glutamate dehydrogenase (GDH) and urease in various plant organs at different growth stages decreased with an increase in Cr (VI) levels from 0 to 4.0 ppm. In general, the enzyme activitiy increased with advancement of growth to reach maximum at 50% flowering stage (70 DAS) and thereafter decreased at grain filling stage (90 DAS). However, nitrite reductase activity in shoot increased continuously till grain filling stage. It is concluded that Cr (VI) at higher doses adversely affects the key enzymes of nitrogen metabolism in forage sorghum ( Sorghum bicolor L.).