The effects of selenium and other micronutrients on the antioxidant activities and yield of corn (Zea mays L.) under drought stress

The effects of selenium (Se) on plant growth under drought stress and in the presence of micronutrients are yet to be investigated. Hence, in a field experiment in 2007 the effects of Se and micronutrients including iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), boron (B) and molybdenum (Mo) were evaluated on corn (Zea mays L.) grain yield under drought stress. Main- and sub-plots were devoted to irrigation (control and water stressed at the eight-leaf, blister and grain filling stages) and micronutrients treatments, respectively. Micronutrients were foliarly applied at 2 l ha(-1) at the six-leaf stage, one week before tasseling, using a corn fertilizer, called biomin containing (on the basis of dry weight percentage) Fe (2.6), Zn (4.1), Cu (1.5), Mn (2.6), B (1.5), Mo (0.5) and Mg (4.1). Se was used as sodium selenite (Na2SeO3), at the rate of 20 g ha(-1) two weeks before treating the plants with drought stress. Effects of drought stress on plant growth were determined based on the activity or level of antioxidants. With increasing the stress level, addition of Se or micronutrients significantly enhanced the antioxidant activity and level as well as corn grain yield. The interaction effects between Se and micronutrients adversely affected antioxidant activity as well as corn grain yield. Se addition at the grain filling stage resulted in the highest grain yield under drought stress. The single but not the combined use of Se or micronutrients can alleviate the unfavorable effects of drought stress on corn yield by affecting plant metabolism including antioxidant activity.