Foliar Potassium-Induced Regulations in Glycine Betaine and Malondialdehyde Were Associated with Grain Yield of Heat-Stressed Bread Wheat (Triticum aestivum L.)

Heat stress at reproductive stages of wheat causes grain shriveling. The present study aimed at comparing thermo-sensitivity of terminal stages of wheat and optimization of foliar potassium to alleviate heat and to determine correlation of biochemical attributes with agronomic attributes. The experiment was laid out in a randomized complete block design under split treatment structure and replicated thrice. Main plot was comprised of heat stress (H), viz. H0 = no heat imposition; H1 = heat stress imposition from complete emergence of spike to grain filling initiation, and H2 = heat stress imposition from flowering initiation to grain filling initiation. Foliar potassium (K) sprays consisted of K0 = control (water spray); K15 = 15; K30 = 30; K45 = 45; and K60 = 60 g L−1. Under “H0” similar and more glycine betaine, water relations and lesser malondialdehyde were recorded with 45 and 60 g L−1 K, While 60 g L−1 K proved more beneficial under “H1” and “H2” for these attributes, “H1” proved more damaging compared with “H0” and “H2” for grain yield and yield components, while similar and more improvements in grain yield and yield components were recorded with 45 and 60 g L−1 K compared with other doses. Conclusively, more deleterious responses were observed under “H1” compared with other heat treatments. Application of 40 g L−1 K under “H0” and 60 g L−1 K under heat stress exhibited more remarkable responses. Moreover, a strong association of biochemical attributes with agronomic parameters was recorded.