Weak Microwave Can Enhance Tolerance of Wheat Seedlings to Salt Stress

The aim of our investigation was to determine the effect of microwave pretreatment of wheat seeds on the tolerance of seedlings to salt stress. Selected parameters (for example, plant growth and biochemical parameters related to oxidative status) were measured. The results showed that microwave pretreatments for 5, 10, 15, or 20 s resulted in an increase in root length and shoot height in seedlings, with 10- and 15-s treatments giving the greatest effect. Salt stress, produced by treatment with 200 mM NaCl, reduced the length and fresh weight of shoots and roots, enhanced the leaf concentrations of malondialdehyde (MDA) and oxidized glutathione (GSSG), indicators of oxidative stress, while decreasing the activities of nitric oxide synthase (NOS), catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), and glutathione reductase (GR). Furthermore, the salt treatment reduced the concentration of nitric oxide (NO) and glutathione (GSH) in the shoots. However, treatments of seeds with microwave radiation followed by salt stress restored all of these parameters close to those in non-salt-treated seedlings. The results indicate that application of a suitable dose of microwave radiation to seeds can enhance tolerance to salt stress in wheat seedlings.