Effect of various nickel levels on growth and chlorophyll content of corn plants supplied with urea and ammonium nitrate.

Both the beneficial and the adverse effects of various nickel level supplements on growth and chlorophyll content of corn plants were evaluated while either urea or ammonium nitrate was applied as the sole N source in the nutrient solutions. This study was arranged in completely randomized design with three replications. Treatments included nutrient solution cultures containing urea and ammonium nitrate at the rate of N 84 mg L -1 separately as nitrogen sources with four nickel levels as NiSO 4 .6H 2 O at the rates of Ni 0, 0.01, 0.05 and 0.1 mg L -1 . Plants were allowed to grow for 6 weeks, and then leaf chlorophyll content and shoot and root fresh and dry weight were determined. Both plant growth and leaf chlorophyll content of the ureafed plants increased significantly with the increase in nickel content up to 0.1 mg L -1 . However, root fresh and dry weight increased up to Ni 0.01 mg L -1 and started to decrease with further increase in solution nickel content. Nickel did not affect these parameters with plants supplied with ammonium nitrate significantly. In these plants, the optimum nickel level for shoot growth and leaf chlorophyll content was 0.05 mg L -1 and for root fresh and dry weight it was 0.01 mg L -1 . Further increase in Ni concentration reduced growth. In total plants that received urea plus nickel performed better than those that received ammonium nitrate plus nickel.