Abstract
Both the beneficial and the adverse effects of various nickel level supplements on growth and chlorophyll content of canola plants were evaluated while either urea or ammonium nitrate was supplied as the sole N source in the nutrient solutions. This study was arranged in completely randomized with three replications. Treatments included nutrient solution cultures containing urea and ammonium nitrate at the rate of 84 mg N L-1 separately as nitrogen sources with four nickel levels as NiSO4.6H2O at the rates of 0, 0.01, 0.05 and 0.1 mg Ni L-1. Plants were allowed to grow for 6 weeks then leaves chlorophyll content and shoots and roots fresh and dry weight were determined. Both plant growth and leaves chlorophyll content of the urea-fed plants increased significantly with the increase in nickel content up to 0.1 mg Ni L-1. However, root fresh and dry weight increased up to 0.01 mg Ni L-1 and started to decrease with further increase in solutions 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 leaves chlorophyll content was 0.05 mg L-1 and for root fresh and dry weight was 0.01 mg Ni L-1. Further increase in Ni concentration reduced growth. As a whole, plants received urea plus nickel performed better than those received ammonium nitrate plus nickel.
Highlights
Urea is the most common forms of combined nitrogen fertilizer used in today’s agricultural practices worldwide (Varina and Obrerza, 1993)
The shoot dry weight was higher at third and fourth nickel levels (0.05 and 0.1 mg L-1) in plants supplied with urea as compared with those supplied with ammonium nitrate. This difference was significant at 1% level. Both roots fresh and dry weight were higher in plants supplied with urea than those treated with ammonium nitrate
The Ni concentration in shoots and roots of urea-fed plants were more than those supplied with ammonium nitrate. These results show that plants growing in media containing urea, application of nickel will probably result in higher urease activity and more urea-N will be available to the plants
Summary
Urea is the most common forms of combined nitrogen fertilizer used in today’s agricultural practices worldwide (Varina and Obrerza, 1993). In 1976, Polacco and in 1978 Gordon and co-workers reported the enhancing effects of nickel on plant growth and development when grown hydroponically and supplied with urea as nitrogen source. Witte and Co-worker (2002) studied the effects of urease activity on nitrogen distribution and nitrogen loss after spraying potato plants with urea. Geibi / Not Sci Biol 1 (1) 2009, 53-58 plants receiving urea as nitrogen source, this enzyme is important for hydrolyzing urea derived from ureides and arginine produced in cytokinins metabolism (Reinboth and Mothes, 1962; Walker et al, 1985; Polacco and Holland, 1993) Urea produced in these processes will cause leaf burn unless detoxified by urease (Eskew et al, 1983; Krogmeier et al, 1989; Stebbins et al, 1991). Finding the optimum nickel levels for maximum growth rate and chlorophyll content for each N-sources used
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
