Sustainable production of bread wheat under terminal heat stress: an investigation of foliar selenium-mediated biochemical regulations in association with yield

High temperature stress during reproductive stages of wheat is a leading constraint in achieving food security. The objectives of study were to investigate heat sensitivity of terminal stages of wheat, to optimize foliar selenium dose, to boost nonenzymatic antioxidants and to determine correlation of these nonenzymatic antioxidants with yield and quality attributes of wheat crop. The field experiment was conducted for two consecutive years at agronomic research area, University of Agriculture Faisalabad, Pakistan. It was laid out in a randomized complete block design under split arrangement, and treatments were replicated thrice. Main plot factor comprised of heat imposition treatments; H 0 = Control; H 1 = Heat from spike to grain filling; H 2 = Heat from flowering to grain filling while in subplots doses of foliar selenium were maintained; Se 0 = Control (water spray); Se 25 = 25 mg L −1 ; Se 50 = 50 mg L −1 ; Se 75 = 75 mg L −1 and Se 100 = 100 mg L −1 . Impact of H 1 was more damaging compared to H 2 and H 0 for all response variables. Higher levels of proline, phenolics and leaf selenium were recorded with foliar spray of selenium either at 75 or at 100 mg L −1 under H 0 , whereas under H 1 and H 2 , significantly higher responses were observed with 100 mg L −1 selenium for these traits. Increases in leaf chlorophyll and grain protein contents were statistically alike with 75 and 100 mg L −1 selenium; while in case of 1000-grain weight, harvest index and grain yield three levels of foliar selenium (50, 75 and 100 mg L −1 ) performed equally well under all the three heat stress treatments. Moreover, strong positive and significant associations of proline, phenolics, leaf selenium and chlorophyll were measured with yield of wheat. Conclusively, more harmful impacts were recorded under H 1 compared to H 2 and H 0 ; while 75 mg L −1 Se proved more beneficial under H 0 and 100 mg L −1 Se under H 1 and H 2 . Strong associations of biochemical and agronomic traits were observed.