Effect of Non-stabilized and Carboxymethylcellulose-stabilized Hematite on Growth and Nutrient Uptake of Maize in Ni-contaminated Soils

Nickel toxicity in agricultural crops is one of the most common problems in recent years. However, few studies have been conducted on the effect of iron oxides on the reduction of nickel toxicity in crops. The goals of this research were to investigate the effects of non-stabilized and Na carboxymethylcellulose (Na-CMC)-stabilized hematite on mobility reduction and phytoavailability of nickel and to study their effects on some agronomic traits, concentrations of phosphorus, potassium, iron, zinc and nickel in maize. For this purpose, a factorial experiment was conducted using a completely randomized design with three replications. The experimental factors were types and dosages of adsorbents; two types of adsorbents including non-stabilized (H) and Na-CMC-stabilized hematite (H-CMC) at four levels (0, 0.25, 0.5 and 1%) and different levels of soil total Ni (25, 75, 125, 175 and 325 mg kg-1). The results showed that with increasing total soil nickel concentration, shoot height, shoot and root dry weight and concentrations of potassium, phosphorus, iron and zinc in the shoot of maize were decreased and nickel concentration increased. At the contaminated level of 325 mg/kg nickel, concentrations of potassium, phosphorus, iron and zinc were decreased about 43.56, 47.98, 73.79 and 86.03%, respectively, and shoot height and dry weight were decreased about 36.86 and 42.56% respectively as compared to control treatment. The results also showed that the application of adsorbents in soil increased the concentration of K, P, Fe and Zn and decreased the concentration of nickel in maize. By applying 0.5% H-CMC, the concentration of nickel in the shoot and root of maize decreased by 52.61 and 46.84% respectively, followed by the concentration of potassium, phosphorus, iron and zinc in the shoot increased about 20.55, 18.68, 61.66 and 48.81% respectively, as compared to control treatment.