The Interactive Effects of Nickel and Iron on Some Agronomic Traits of Corn (Zea mays L.) in a Calcareous Soil

Nickel (Ni) is an element that has recently been added to the list of essential micronutrients of plants. On the other hand, accumulation of Ni in soils and plants has increased concerns about humans and other living organisms for toxicity of Ni. To study the effect of Ni and iron (Fe) on the growth characteristics of corn (Zea maysL.) plant in the soil a factorial experiment on the basis of randomized complete blocks design with three replications was carried out under greenhouse condition in a calcareous soil. The factors included the concentration of the applied Ni at four levels (0, 10, 50 and 100 mg Ni kg-1 soil) as pure nickel sulfate (NiSO4.6H2O) source and Fe at five levels of 0, 10 and 20 mg Fe kg-1 soil, as iron sulfate (FeSO4.7 H2O) and commercial Fe sequestrene (FeEDDHA). According to the results, at the applied levels of 50 and 100 mg Ni kg-1 soil, the shoot dry weight was decreased by 21.1 and 31.9%, and the relevant decrease of root dry weight was 30.8 and 28.5% respectively, as compared to the control. Stem height was decreased by 2.1% in the presence of 100 mg Ni kg-1 soil, as compared to the control. Chlorophyll index was decreased by 32.4 and 40.5% in levels of 50 and 100 mg Ni kg-1 soil, respectively, as compared to the control. Increasing Fe levels of the two applied Fe sources significantly increased the shoot dry weight. But the shoot dry weight was decreased by 81.9 and 29% at 20 mg Fe level of Fe-EDDHA, as Ni was increased from the levels of 10 to 50 mg and from 50 to100 mg, respectively.