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

The aim of the present work was to study the effect of foliar application of micronutrients [Zinc: Zn 1 (0%); Zn 2 (0.5%); Zn 3 (1.0%) and Boron: B 1 (0%); B 2 (0.25%); B 3 (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 Zn 1 B 3 (0% of Zn in combination with double dose of 0.5% of B) was proved to be most promising with respect to antioxidant properties.