Protective role of foliar-applied nitric oxide in Triticum aestivum under saline stress

A study was conducted to assess whether foliar-applied nitric oxide (NO) could alleviate the adverse effects of salt stress on wheat (Triticum aestivum L.). Four sodium nitroprusside levels (control [water spray] and 0.05, 0.10, and 0.15 mM) were sprayed as a donor of NO on the leaves of cultivar S-24 plants grown under nonsaline and saline conditions (150 mM NaCl). Data for growth and yield, chlorophyll contents, activities of antioxidants, and concentrations of mineral nutrients were recorded. Root-medium salinity adversely affected shoot and root dry weight, shoot length, and yield attributes of the wheat plants while it enhanced the activities of antioxidants, proline accumulation, and concentrations of shoot and root Na+ and Cl-. Foliar-applied NO improved growth of only nonstressed plants. Exogenously applied NO enhanced the activities of antioxidant enzymes (superoxide dismutase [SOD], peroxidase [POD], and catalase [CAT]) and levels of soluble proteins and proline, in both stressed and nonstressed wheat plants. Overall, exogenous application of NO enhanced chlorophyll contents; activities of CAT, POD, and SOD; and levels of soluble proteins and total free proline in the salt stressed wheat plants. The exogenous application of NO had a protective role against salt-induced oxidative damage by enhancing the activities of antioxidant enzymes, thereby improving plant growth under saline stress.