Effect of selenium priming on antioxidant properties and photosynthetic pigments of Quinoa (Chenopodium quinoa Willd.) under PEG drought stress

Plants often encounter unfavorable conditions, which interrupts their growth and productivity. Among the various abiotic stresses, drought is the major factor that limits crop productivity worldwide. Shortage of water causes drought that is the most dangerous hazard to food security all over the world. Because water supply is limited all over the world, food demand becomes a major problem. Priming of plant seeds is an easy, low-cost, low-risk, and effective approach to improve plant tolerance under stressful environment. . Priming of plant seeds is an easy, low-cost, low-risk, and effective approach to improve plant tolerance under stressful environments. In nutrient priming, seeds are pretreated (primed) in solutions containing the limiting nutrients instead of being soaked just in water. The physico-chemical and anti-oxidative properties of selenium (Se) have raised the curiosity of biologists in recent past. Research shows that selenium promotes the plant growth and may act as heavy metal opponent as it is a necessary micronutrient with some physiological and anti oxidative properties. However, for plants, studies has shown that although low concentrations of selenium can effectively promote plant growth, high concentrations of selenium have a significant toxic effect on plants.

Thus in order to investigate different concentrations of selenium (Na2Seo4) on antioxidant properties and photosynthetic pigments of quinoa under experimental drought stress conditions with 5 levels of selenium priming with sodium selenate source (0.5, 1.5, 3, 4.5 and 6 mg l-1), and two levels of hydropriming without priming and three levels of drought stress using polyethylene glycol (PEG) (0.4, 0.8 and 1.2 MPa) with three replications in Seed Technology Laboratory of Shahed University of Agricultural Sciences was conducted in 1398. Measured traits include antioxidant enzymes including catalase, superoxide dismutase, ascorbate peroxidase, and photosynthetic pigments, proline, and protein. Statistical analysis of the data included analysis of variance using AS 9.1 software and comparison of mean of traits evaluated by LSD test at 5% probability level.

The results showed that the application of drought and prime stress with sodium selenate had a positive and significant effect on antioxidant enzymes, photosynthetic pigments, proline and protein content. Seed priming with sodium selenate increased the activity of antioxidant enzymes including catalase, superoxide dismutase and ascorbate peroxidase under drought stress. Based on the results under stress conditions, protein content and photosynthetic pigments showed a decreasing trend and prime with sodium selenate slowed down this decreasing trend. The highest amount of proline in stress of 1.2 MPa and prime with sodium selenate with a concentration of 4.5 mg l-1 showed a 66% increase compared to drought stress of 0.4 MPa and no priming.