To study the effect of microwave pretreatment on wheat seeds on the resistance of seedlings to osmotic stress and to evaluate the potential biological effects of low-level microwaves on oxidative damage (induced by osmotic stress).
High activities of antioxidant enzymes and high contents of non-enzymatic constituents (e.g. antioxidants) are important for plants to tolerate environmental stresses.
Six different doses of microwave exposure (0, 5, 10, 15, 20, 25 s) were tested to select the best dose for a following protective experiment (resistence to osmotic stress). In the protective experiment, wheat seeds were randomly divided into four experimental conditions: 1) control group, 2) microwave exposure, 3) osmotic stress: polyethylene glycol 600, 4) microwave exposure (10 s) + osmotic stress (polyethylene glycol 600). At least three replications were performed.
|Exposure duration||5, 10, 15, 20 or 25 s|
The seed temperature increased progressively with microwave pretreatment dose compared to the control group. Each microwave pretreatment resulted in an increased α-amylase enzyme activity and biophoton emission intensity with a peak value at microwave pretreatment of 10 s.
In the seedlings with microwave exposure and osmotic stress (group 4), the concentration of malondialdehyde decreased, while the enzyme activities of nitric oxide synthase, catalase, peroxidase, superoxide dismutase and concentration of nitric oxide, ascorbic acid and glutathione increased.
The results suggest that a suitable dose of microwave exposure can enhance the capability of plants to eliminate free radicals and thus may alleviate water deficit induced by osmotic stress in wheat seedlings.