Improving the Spike Initiation and Flowering Stage Heat Tolerance in Bread Wheat Through Foliar Application of Potassium

Coincidence of heat with terminal stages of wheat is chief constraint to accomplish yield potential. The present study was aimed at comparing thermo-sensitivity of terminal stages, optimizing foliar potassium to alleviate heat and exploring association of metabolites with agronomic attributes. The experiment was laid out in randomized complete block design under split arrangement and repeated over 2 years. Treatments comprised heat stress imposition in main plots viz. H0 = No heat stress; H1 = heat imposition from spike initiation to grain filling initiation and H2 = heat imposition from flowering initiation to grain filling initiation and foliar potassium (K) in sub plots viz. K0 = Water spray (control), K15 = 15 g L−1 K; K30 = 30 g L−1 K; K45 = 45 g L−1 K and K60 = 60 g L−1 K. Imposition of ‘H1’ proved more deleterious for metabolites, water relations and agronomic attributes compared to ‘H0’ and ‘H2’. Application of 45 g L−1 K proved beneficial for enhancing the synthesis of phenolics, proline, soluble proteins and for improving water potential under ‘H0’. While, 60 g L−1 K induced more promising responses in these attributes under ‘H1’ and ‘H2’. Application of 45 and 60 g L−1 K proved equally effective for improvement of agronomic traits compared to other doses over H0, ‘H1’ and ‘H2’. Decisively, more promising responses were observed with 45 g L−1 potassium under ‘H0’ and 60 g L−1 potassium under ‘H1’ and ‘H2’. Agronomic attributes were strongly associated with biochemical parameters.