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. H-0 = no heat imposition; H-1 = heat stress imposition from complete emergence of spike to grain filling initiation, and H-2 = heat stress imposition from flowering initiation to grain filling initiation. Foliar potassium (K) sprays consisted of K-0 = control (water spray); K-15 = 15; K-30 = 30; K-45 = 45; and K-60 = 60 g L-1. Under H-0 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 H-1 and H-2 for these attributes, H-1 proved more damaging compared with H-0 and H-2 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 H-1 compared with other heat treatments. Application of 40 g L-1 K under H-0 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.