Exogenous Potassium–Instigated Biochemical Regulations Confer Terminal Heat Tolerance in Wheat

Abstract

Heat stress at spike initiation and flowering is chief constraint hampering the accomplishment of yield potential in wheat crop. The present study was aimed at comparing the thermo-sensitivity of terminal stages, optimizing exogenous potassium to alleviate impacts of heat and to explore biochemical attributes triggered regulations in morphological attributes of wheat. The experiment was performed at the University of Agriculture Faisalabad, Pakistan during winter 2015-2016 and 2016-2017. The experiment was laid out in Randomized Complete Block Design under split arrangement and replicated thrice. The treatments comprised of heat stress in main plots 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 and exogenous potassium (K) concentrations in split plots viz. K 0 = Control (water spray); K 15 = 15 g L −1 ; K 30 = 30 g L −1 ; K 45 = 45 g L −1 , and K 60 = 60 g L −1. Under BH 0 ,^statistically similar and relatively more activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were quantified with 45 and 60 g L −1 foliar BK.^Contrarily, significantly more SOD, POD, and CAT contents were recorded with 60 g L −1 exogenous potassium under BH 1â nd BH 2^w hile significantly lesser chlorophyll a, b contents and grain yield were recorded under BH 1^c ompared to BH 0^a nd BH 2 ,ŵ hereas statistically similar and significantly more grain-filling rate (GFR) and statistically similar and significantly lesser grain filling duration (GFD) were observed under BH 1^c ompared to BH 0^B H 2 .^Exogenous application of K at 45 and 60 g L −1 depicted statistically similar and comparatively more chlorophyll a, b contents, GFR, GFD, and grain yield compared to control. Moreover, strong, positive, and significant association of antioxidants and chlorophyll contents with morphological attributes was observed. Conclusively, BH 1^p roved more deleterious compared to BH 0^a nd BH 2^a nd exogenous K at 60 g L −1 effectively alleviated adversities of heat. Moreover, K-mediated regulations in biochemical attributes improved morphological attributes of heat-stressed wheat crop.

Strengthening leaf physiological functioning and grain yield formation in heat-stressed wheat through potassium application

“…In heat tolerant genotype, K improved thermotolerance by strengthening the leaf physiology and membrane stability ( Xu et al, 2011 ). This implies that exogenous application of K in heat tolerant wheat genotypes could further improve leaf physiology and membrane stability, representing a good indicator of heat tolerance ( Dias and Lidon, 2010 ; Shahid et al, 2019 ) and supports our initial hypothesis and objectives.…”

“…Potassium is an important plant nutrient and has a role in heat stress in maintaining photosynthesis, translocation of water-soluble carbohydrates and stimulating the plant defensive system ( Hasanuzzaman et al, 2018 ). Exogenous application of K and higher leaf concentration of K improve heat stress and salt stress tolerance in maize and wheat under field and controlled conditions ( Abbasi et al, 2014 ; Shahid et al, 2019 ). We found good support for our hypothesis that foliar spray of K alleviated the adverse effects of heat stress on wheat grain yield.…”

Effects of Spraying KH2PO4 on Flag Leaf Physiological Characteristics and Grain Yield and Quality under Heat Stress during the Filling Period in Winter Wheat

“…Optimizing water and fertilizer management is another critical aspect in controlling wheat growth, enhancing its resilience to adversity and reducing the negative impacts of heat stress at harvest on the yield [34,35]. Exogenous mineral fertilizer administration can also greatly increased crop resistance to abiotic stress, which is a financially viable strategy to reduce the impacts of terminal heat stress on wheat production [36,37]. Potassium dihydrogen phosphate (KH 2 PO 4 ), as a high-quality and effective common foliar fertilizer, plays an important role in crop stress resistance and yield improvement [38,39].…”

Pre-treatment for heat tolerance enhancement of the Indian almond (Pithecellobium dulce) seedlings using ascorbic acid and potassium chloride

“…Potassium is an element that modulates the osmotic pressure in plant cells (osmoticum) to relieve various stresses (Shahid et al, 2019). Potassium-induced regulation of plant water relations reduces heat sensitivity, while potassium availability under stress enhances photosystem II quantum yield, enzymatic activities, and chlorophyll biosynthesis.…”