Green Synthesized Zinc-Glycine Chelate Enhances Antioxidant Protection of Pistachio under Different Soil Boron Levels

ABSTRACT

Zinc (Zn) and boron (B) disorders are common nutritional stresses in arid and semi-arid regions. In the current study, effectiveness of soil Zn amendment (0, 5.0, 10.0, and 20.0 mg kg^–1 soil) using Zn-glycine chelate (Zn-Gly), a novel Zn-fertilizer, which is especially synthesized for application in calcareous soils in arid and semi-arid areas, was evaluated under different soil B levels (0, 2.5, 5.0, 10.0, and 20.0 mg kg^–1 soil) for a 100-day period. Pistachio, the most valuable crop grown under arid conditions, was used as the model plant. Measurement of electrolyte leakage, H₂O₂, and malondialdehyde indicated the incidence of oxidative stress in the leaves of pistachio under low and high soil B concentrations. In addition, B stress caused a significant increase in lipoxygenase activity in the leaves. Plants treated with 5.0 mg B kg^–1 soil showed the lowest oxidative stress injuries and lipid peroxidation. Application of 5.0 mg Zn kg^–1 soil significantly alleviated the B stress damages, however, the ameliorative effect of Zn was vanished by application of higher Zn concentrations. Evaluation of the antioxidant enzymes (superoxide dismutase [SOD], catalase [CAT], or ascorbate peroxidase [APX]) and non-enzyme antioxidants (ascorbate and phenolic compounds) revealed that the protective effects of Zn-Gly against B stress are due to enhancement of cell antioxidant defense. In conclusion, application of Zn-Gly for reducing oxidative stress pressure in pistachio plants grown under B disorder was suggested.

KEYWORDS:

• Antioxidant enzymes
• boron
• oxidative stress
• pistachio
• Zn-glycine chelate