The effects of selenium on physiological traits, grain selenium content and yield of winter wheat at different development stages.

The paper evaluated the effects of Se application time and rate on physiological traits, grain Se content, and yield of winter wheat by field experiment. Se application significantly increased grain Se content and yield, and the increased amount treated with 20 and 30 mg Se L(-1) was the highest. At blooming-filling stage, Se application significantly increased grain Se content, but did not affect yield. Chlorophyll content was increased by Se application, and the increased amount at heading-blooming stage was higher than that in wheat leaves at the other stages. At four development stages, Se treatments (except for 10 mg Se L(-1) at jointing-heading stage) significantly decreased the rate of superoxide (O(2) (-)) radical production. At heading-blooming (except for 50 mg Se L(-1)) and blooming-filling stages, hydrogen peroxide (H(2)O(2)) content was significantly decreased by Se treatments. The rate of O(2) (-) production and H(2)O(2) content at 20 and 30 mg Se L(-1) was the lowest. Se treatments (except for 10 mg Se L(-1) at regreening-jointing and blooming-filling stages) also induced an evident decrease in malondialdehyde content. Proline content induced by Se treatments at jointing-heading and heading-blooming stages was higher than that in wheat leaves at regreening-jointing and blooming-filling stages. At four development stages, Se treatments all significantly increased glutathione peroxidase activity, and the treatments with 20 and 30 mg Se L(-1) also evidently increased reduced glutathione content. These results suggested that Se application at different development stages increased antioxidant capacity of wheat, reduced oxidant stress to some extent, and the effects of Se treatments was the best if Se concentration ranged between 20 and 30 mg Se L(-1). In addition, Se application time was more beneficial for Se accumulation and yield in wheat grain at heading-blooming stage.