Selenium supply methods and time of application influence spring wheat (Triticum aestivum L.) yield under water deficit conditions

Identification of new effective strategies for improving crop yields under environmental stresses such as drought represent key priorities for researchers around the globe. In the present study, the effects of different methods of exogenous selenium (Se) supply viz. Se seed priming, Se fertigation and Se foliar spray on yield of spring wheat under normal and water deficit conditions were investigated. Two field experiments were conducted using one indigenous drought-tolerant genotype (Kohistan-97) and a sensitive genotype (Pasban-90) to understand the role of Se in improving wheat yield. The experiments were laid out in a split-split plot design with three replications during consecutive years (2011/12 and 2012/13) and the plants were exposed to water stress by withholding irrigation at two different wheat growth stages, viz. tillering and anthesis. It was noted that drought stress significantly affected the yield attributes of wheat; however, exogenous Se supply was observed to be helpful in improving the drought tolerance potential and yield of water-stressed wheat plants through maintenance of plant water status. A significant increase in wheat yield by Se supply was also noted under normal conditions. The normal plants fertigated with Se maintained the highest values for number of productive tillers, spike length, number of grains per spike, thousand-grain weight, biological and grain yield with no significant difference from Se foliar spray at the tillering stage, which was found to be the most effective method of exogenous Se supply for improving wheat yield under water deficit conditions. Moreover, Se fertigation and foliar spray resulted in the maximum accumulation of Se in shoots and gave the highest net return and cost-benefit ratio under drought stress conditions. The present study is one of the few reports on the role of Se in alleviating water stress for obtaining maximum profit in field grown spring wheat.