Effect of Foliar Application of Micronutrients on Antioxidants and Pungency in Onion

Abstract

The aim of the present work was to study the effect of foliar application of micronutrients [Zinc: Zn₁ (0%); Zn₂ (0.5%); Zn₃ (1.0%) and Boron: B₁ (0%); B₂ (0.25%); B₃ (0.5%)] on the antioxidants and pungency of onion cv. “Sukhsagar” (Allium cepa L.). In this experiment, it was suggested that the highest contents of total and free phenol was obtained by the highest dose of Zn (1%) in combination with 0% B, and single dose of Zn (0.5%) in combination with 0% B respectively. The superoxide dismutase (SOD) activity was found to increase with respect to control following the highest dose of B (0.5%) alone. However, the peroxidase (POD) activity increased more with respect to control following the single dose of B (0.25%) rather than the double dose (0.5%). The highest Molybdate reducing antioxidant potential (MRAP) was observed in 0.5% Zn in combination with 0% B, whereas that of 2, 2-Diphenyl-β-picrylhydrazyl radical scavenging activity (DPPHRAC) was found in the interaction effect of the double doses of both Zn (1%) and B (0.5%), which also offered the lowest lipid peroxidation. The highest pyruvic acid development was observed by the interaction effect of 0% Zn and 0.25% B. Based on the average values of the biochemical parameters and the results of PCA, the treatment with Zn₁B₃ (0% of Zn in combination with double dose of 0.5% of B) was proved to be most promising with respect to antioxidant properties.