Does Exogenous Selenium Elicited Biochemical Regulations Make Economic Improvements in Terminally Heat-Stressed Bread Wheat? An Evidence from Marginal Analysis

Heat spell during the reproductive growth of wheat is a serious threat to achieve food security. An experiment was conducted with the objectives (i) to explore the optimum dose of foliar selenium for alleviation of heat, (ii) to investigate the thermo-lability of reproductive stages of wheat, (iii) to enquire about the correlation of biochemical attributes with agronomic traits, and (iv) to determine the economic feasibility of foliar selenium for alleviation of adverse impacts of heat on wheat. The study was conducted over 2 years using a split treatment structure in a randomized complete block design. Treatments were comprised of H 0 (control), H 1 (heat imposition from spike to grain filling), and H 2 (heat imposition from flowering to grain filling). Foliar doses of selenium (Se), viz., Se 0 = water spray (control); Se 25 = 25 mg Se L −1 ; Se 50 = 50 mg Se L −1 ; Se 75 = 75 mg Se L −1 and Se 100 = 100 mg Se L −1 were maintained in sub plots. The longer heat spell proved more deleterious than the shorter one. More catalase, glycine betaine, water potential, turgor potential, grain filling rate, spikelets per spike, grains per spike, and grain yield were recorded with 75 mg Se L −1 under “H 0 ,” while remarkably higher responses of these attributes were observed with 100 mg Se L −1 under “H 1 ” and “H 2 .” Based on marginal analysis, applying “75 mg Se L −1 ” resulted in higher economic benefits under “H 0 ” and “H 1 ,” whereas 50 mg L −1 was more economical to apply under “H 2 .” Moreover, strong associations of physiochemical attributes with agronomic traits were observed. Decisively, applying “75 mg Se L −1 ” on terminally heat-stressed wheat produced more benefits compared to other doses.