It is known that phytotoxicity of nickel (Ni) vanes within plant species and
varieties according to its concentration in the root medium. Moreover, several
nutrients can modify the plant response to Ni excess. Because nitrogen can be absorbed by plants as NO;- or NH; and N metabolism are closely related to Ni, a
hydroponic experiment was conducted to study the effect of Ni toxicity on the growth
of maize (Zea mays L.). Nutrients status of the different plant parts and leaf
chlorophyll concentrations were also taken into consideration. A single cross hybride
Giza 10 grown for 40 days with either forms of N supply. The obtained results
indicated that a significant differences in the sensitivity of maize plants to Ni excess.Where.the plant tolerance to Ni toxicity was lowest when grown with NO ;- supply alone.ln this concern a high increase of Ni in the presence of NO;- as the only
source of nitrogen caused a significant decreases of both maize dry weight and
nutrient concentration. But ,when plants supplied with Ni in the presence of mixture of NO;- and NH; , the absorption of Ni by plant was less than those supplied with NO ;-
alone. This decrease reached to about three times. This clearly indicates that, there
were great differences in Ni concentrations between treatments. The addition of nitrogen as NO;- alone , Ni supply led to severe growth inhibition. Just contrary. nitrogen supply as NO;- and NH; together not only reduced Ni toxicity, but Ni might
enhance and stimulate the growth of maize plants.Therefore,confirm this Important
role of the N form in the Ni behaviour in plants.