Effect of soil Zn deficiency on antioxidant enzymes activity and biochemical parameters in bread wheat

A factorial experiment was conducted in greenhouse in a completely randomized design (CRD) with three replications to investigate the response of Zn-efficient and -inefficient bread wheat cultivars to soil Zn deficiency. The factors of the experiment were soil Zn levels (Zn-adequate: 5mg Zn kg-1 soil and no Zn application), Zn-efficient (Bayat and Niknejad) and -inefficient (Hirmand and Karaj1) cultivars, sampled tissues (Root and leaf) and growth stages (28 days after germination: vegetative and 30% of heading: reproductive). The activity of superoxid dismutase, catalase, ascorbate peroxidase, peroxidase and phenylalanine ammonia-lyase enzymes were measured in the root and leaf of the cultivars. Also, the content of malondialdehyde, hydrogen peroxide, prolin, phenol and total antioxidants were investigated. The results of variance analysis and mean comparison for main and interaction effects revealed that soil Zn deficiency enhance the activity of ascorbate peroxidase, peroxidase and phenylalanine ammonia-lyase, while the activity of superoxid dismutase significantly (P≤0.01) declined. The content of malondialdehyde, hydrogen peroxide, phenol and prolin siginificantly (P≤0.01) increased under Zn deficiency conditions. The enzymes activity and prolin content in Zn-efficient cultivars were higher than those of inefficient cultivars, whereas the minimum amount of malondialdehyde and hydrogen peroxide were observed in Zn-efficient cultivars. Catalase activity in Bayat (Zn-efficient) cultivar under Zn deficiency conditions was more than that of other cultivars. In conclusion, the results of the current study demonstrated the enhanced activity of the antioxidant enzymes in bread wheat cultivars under soil Zn deficiency conditions.