Hydrogen Peroxide Improves the Antioxidant Defence System in Salt Stressed- &amp;lt;i&amp;gt;Allium cepa&amp;lt;/i&amp;gt; Plants

Taia Ali Abd El-Mageed

doi:10.11648/j.plant.20160406.16

Abstract

As one of the active oxygen species that is widely generated in many biological systems and mediates various physiological and biochemical processes in plants, exogenous hydrogen peroxide (H2O2) in very low concentrations improves salt-tolerance in some plant species. Therefore, two field experiments were conducted in 2013/14 and 2014/15 to study the effect of foliar sprays at concentrations of 1 and 2 mM H2O2 on growth, yield, plant water relations, osmoprotectants and the activity of antioxidant system in two onion varieties grown under saline soil condition (ECe = 7.94 - 8.81 dS/m). Exogenous H2O2 enhanced salt stress tolerance in onion plants by reducing the endogenous H2O2 and lipid peroxidation, and increasing enzymatic (i.e., superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) and non-enzymatic antioxidant (i.e., ascorbic acid and glutathione) activity. Moreover, H2O2 application significantly affected photosynthetic efficiency and plant water status as evaluated by relative water content and membrane stability index. These results were positively reflected by the increase in plant growth, productivity and water use efficiency under salt stress conditions. H2O2 may participate in enzymatic and non-enzymatic antioxidant activity, inducing salt-tolerance in onion plants.

Highlights

Salt stress is considered one of the major limiting factors to plant growth and crop production in many areas, in arid and semi-arid regions
Exogenous H2O2 remarkably promoted onion plants growth under salt stress (Table 4)
The data indicate that the Giza 20 variety was more sensitive to soil salinity, while it was more responsive to the foliar application with 1 mM H2O2

Summary

Introduction

Salt stress is considered one of the major limiting factors to plant growth and crop production in many areas, in arid and semi-arid regions. Salt stress negatively affects plant morphology and physiology through osmotic and ionic stress, and changes biochemical responses in plants [1] It causes osmotic stress (a physiological drought problem), adversely affecting water relations and ion homeostasis in plants, leading to toxic-ion effects on metabolic processes [2]. Salt stress decreases photosynthetic attributes [4], plant growth and development [5], and stimulates the activity of antioxidant system [6, 7]. To overcome these salt stress effects, plants develop several mechanisms to induce their tolerance such as ion homeostasis, osmotic adjustments, stress damage control and repair, and growth regulation [8]

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Conclusion