Pak. J. Bot., 53(5): 1553-1560, 2021. DOI: http://dx.doi.org/10.30848/PJB2021-5(17) FOLIAR APPLIED SALICYLIC ACID AMELIORATES WATER AND SALT STRESS BY IMPROVING GAS EXCHANGE AND PHOTOSYNTHETIC PIGMENTS IN WHEAT ZAHOOR AHMAD 1 , EJAZ AHMAD WARAICH 2 , RANA MUHAMMAD SABIR TARIQ 3 , MUHAMMAD AAMIR IQBAL 4 , SAJID ALI 5 , WALID SOUFAN 6 , MONTASER M. HASSAN 7 , M. SOHIDUL ISLAM 8 AND AYMAN EL SABAGH 9 * 1 University of Central Punjab, Bahawalpur Campus, 63100, Pakistan 2 Department of Agronomy, University of Agriculture Faisalabad, Pakistan 3 Department of Agriculture & Agribusiness Management, University of Karachi, Karachi, Pakistan 4 Department of Agronomy, Faculty of Agriculture, University of Poonch Rawalakot, Rawalakot-12350 (AJK), Pakistan 5 Institute of Agricultural Sciences, University of the Punjab, Lahore, Pakistan 6 Plant Production Department, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia 7 Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia 8 Department of Agronomy, Hajee Mohammad Danesh Science and Technology University, Dinajpur, Bangladesh 9 Department of Agronomy, Faculty of Agriculture, Kafrelsheikh University, Kafr El -Sheikh, Egypt *Corresponding Author’s Email: ayman.elsabagh@agr.kfs.edu.eg Abstract Abiotic stresses adversly effect the growth and physiological processes in crop plants, which ultimately lead to significant reduction in the yield. Based upon emerging threats of salinity and drought stresses, present investigation was done to evaluate the effect of foliar applied salicylic acid (SA) on the growth, gas exchange attributes and leaf pigments in wheat under water and salt stress. The experiment was conducted in a warehouse upon three commercial wheat varieties (Galaxy-2013, Punjab-2011 & Millat-2011) treated with two levels of foliar application of SA (Control, SA @ 100 mg/L) under CRD-factorial arrangement which was replicated thrice. According to the results, all the growth attributes, pigments and gas exchange parameters were significantly (p≤0.01) affected by the salt and drought stresses, and foliar application of SA remarkably remediated the adverse effects of stresses and improved the studied traits in all wheat cultivars. Elevated levels of chlorophyll a (2.31 mg g -1 FW), chlorophyll b (3.24 mg g -1 FW) and total chlorophyll content (5.55 mg g -1 FW) were found in SA treated plants under both types of stresses. Similarly, the maximum leaf photosynthetic rate (5.33 µmol CO 2 m -2 s -1 ), leaf transpiration rate (3.47 mmol H 2 O m -2 s -1 ) and stomatal conductance (0.85 mmol H 2 O m -2 s -1 ) were recorded by Glaxy-2013 under foliage applied SA (100 mg/L. In conclusion, wheat cultivar Glaxy-2013 surpassed all other cultivars by exhibiting significantly improved growth attributes salt and drought stresses. Key words: Growth, Gas exchanges attributes, Pigments, Foliar A, Wheat. Introduction Drought and salinity are the leading causes globally for reducing the crop yields by 28-59%, depending upon the level of stress and the crop species ( Wang et al., 2017; Ahmad et al., 2020). Vital biochemical processes occurring in plants including photosynthesis and transpiration are negatively affected owing to drought and salinity (Tiwari et al., 2010; Waraich et al., 2013; EL Sabagh et al., 2019a). These stresses are directly linked to inflicting oxidative damage which led to cell death (Ahmad et al., 2018a). Drought causes significant reduction in growth & physiology of crops (Naeem et al., 2018; Bukhari et al., 2020). Photosynthesis, in particular, is much more affected due to stomatal limitations. Waraich et al., (2020a) reported that the closure of stomata is the first response of plants to drought. No doubt stomatal closure is essential to retain the available moisture of plants under stress, meanwhile, it also reduce the CO 2 absorption, inducing the extended stress for the longer time (Ahmad et al., 2018b). However, salt stress exerts more drastic effects in terms of less productivity (Munns, 2002). Higher level of salts affects the physiological processes by modifying the ionic balance, water potential status, mineral nutrition and altered photosynthetic rate due to stomatal behavior (Hamid et al., 2010; Zafar et al., 2018). Salicylic acid (SA) a hormone-like substance has been found to play a crucial role in boosting photosynthetic rate along with increasing stomatal conductance and transpiration (Khan, 2003; Arfan et al., 2007; Akhtar et al., 2013). Antioxidative protection and inhibiting Na + and Cl - accumulation have also been recorded to be controlled by SA (Gunes et al., 2006). A number of investigations have reported that SA is a useful substance to reduce the drastic impact of salinity (Shakirova et al., 2003; Hamid et al., 2010) and drought (Singh & Usha, 2003) stresses. The underlying mechanism of regulating the activities of antioxidants and ultimately making crop plants more tolerant to stresses favors exogenous application of SA to cope with abiotic stresses (Eraslan et al., 2007; Hayat et al., 2010; Kadioglu et al., 2011). However, SA always needs to be optimized for different crops, mode of application and level of the stress induced. Wheat (Triticum aestivum L.) is a staple food and a cash crop of Pakistan, contributing 2% to the national GDP and overall 9.9% to the value added in agriculture (Siddiqui et al., 2019; Iqbal et al., 2020). Area under wheat cultivation in Pakistan is 9204 thousand hectares showing an increase of 0.6% as compared to the previous year (Government of Pakistan, 2019). Wheat yield is much lower than its true potential (Iqbal et al., 2018; Youldash et al., 2020) which has compromised the food security of