Exogenous nitric oxide protect garlic plants against oxidative stress induced by salt stress

Abstract

One of the most important environmental stresses in agriculture is soil salinity. This study was conducted to assess the effects of NaCl level on growth, relative leaf water content, electrolyte leakage, chlorophyll and photosynthetic pigment content, antioxidant activity and antioxidant enzyme activity of marketable Garlic (Allium sativum L.) in a hydroponic greenhouse experiment. Garlic plants were treated with NaCl (0, 30, 60 and 90 mM) and sodium nitroprusside application (0, 75 and 150 μg L−1). The results showed that sodium nitroprusside treatment improved the vegetative characteristics of plants (number of leaves, bulb length and dry weight of bulb) under salinity stress. The highest relative water content of leaves was observed in the treatment of 75 μg L−1 sodium nitroprusside and the level of 30 mM sodium chloride. Application of 75 μg L−1 of sodium nitroprusside could prevent the increase of lipid peroxidation at the level of 60 mM sodium chloride. The simple-effects analysis showed that with increasing the concentration of NaCl and also increasing the concentration of SNP, the amount of chlorophyll a, b and total chlorophyll were decreased. Sodium nitroprusside (75 μg L−1) could improve the damaging effect of salinity stress by increasing the activity of superoxide dismutase, peroxidase, and ascorbate peroxidase enzymes. Application of sodium nitroprusside (75 μg L−1) at level 90 mM NaCl, increased the activity of glutathione reductase enzyme compared to the control at the same level. The results showed that the exogenous application of NO protected garlic plants against salt stress-induced oxidative damage by enhancing the biosynthesis of antioxidant enzymes, thereby improving plant growth under saline stress.