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.

Effect of zinc fertilisation on yield and selected qualitative parameters of broccoli

“…In the zinc treatments, the decrease of AOA by about 3.7-4.2% (Zn 0.75 ) and 5.3-7.0 (Zn 1.50 ), compared to the control was detected. It is consistent with the study of Denre et al (2016), who discovered significantly lower value of AOA (DPPH) in onion after foliar zinc application in comparison with the control (-19.3%). Denre et al (2014b) and Salama et al (2015) similarly mentioned the negative impact of zinc fertilisation on the AOA in experiments with green chilli (-4.8%) and maize plants (-18.3%, on average).…”

“…The effect of zinc fertilisation to the TPC in broccoli is not well-proved and the experimental results with other crops are markedly different. The lower TPC, as a result of foliar zinc application, was also shown in an experiment with onion (Denre et al 2016). The obtained experimental results are in strong contrast with the study of Denre et al (2014a), who found higher TPC after foliar zinc spraying in the fruits of pungent pepper (+18.6% compared to the control).…”

Comparasion of phenylalanine ammonia lyase response to lead and zinc stress in different wheat genotypes

“…Plants exposed to biotic and abiotic stresses generate large amounts of Reactive Oxygen Species (ROS), and accumulation of ROS in large amounts leads to cell damage [17,18]. Excessive Zn and Pb in case of heavy metal stress affect the intake of other nutrition elements, and cause oxidative stress [19]. Plants develop a kind of tolerance-defense mechanism against various biotic and abiotic stresses using secondary metabolites, antioxidants, and various allelochemicals (such as phenolic).…”