Contents lists available at ScienceDirect Journal of Cereal Science journal homepage: www.elsevier.com/locate/jcs Sustaining zinc bioavailability in wheat grown on phosphorus amended calcisol Sundas Yousaf a,* , Muhammad Akhtar b , Nadeem Sarwar b , Wasiq Ikram a,c , Saddam Hussain d,** a Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan b Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan c School of Botany, Minhaj University Lahore (MUL), Lahore, Pakistan d Department of Agronomy, University of Agriculture, Faisalabad, Pakistan ARTICLE INFO Keywords: Estimated Zn bioavailability ZnSO 4 application Phytate to zinc ratio Phosphate fertilizers ABSTRACT The deficiency of zinc (Zn) and phosphorus (P) occurs widely in alkaline calcareous soils, and the antagonism between these two elements is also a major cause of low Zn uptake in wheat, leading to low productivity and quality. The present study investigated the different methods of Zn application for wheat cultivars [i.e. Faisalabad-2008 (Fsd-08) and Zincol] grown on P amended calcisol. Data regarding yield component, estimated Zn bioavailability and phytate content in grain were recorded. Compared to zero P control, application of phosphoric acid (PA) and di-ammonium phosphate (DAP) to wheat cultivar Fsd-08 increased biological yield by 49.1 and 76.4%, grain yield by 45.5 and 43.1%, and grain-P by 79.2% and 25.6%, respectively. The Zn-treat- ment (irrespective of mode of its application) produced higher grain Zn content, however, application of PA and DAP decreased grain Zn concentration by 26.5 and 30.5%, respectively relative to zero P treatments. Almost similar trend was observed in Zincol cultivar in terms of increase in yield parameters and grain-P and Zn content of wheat. The phosphate application also affected phytate to Zn molar ratio (PZR) which was usually found lower in Zincol (range: 12–35) while higher in Fsd-08 (range: 12–43). Overall, PA application was found to have higher beneficial effects in terms of increasing yield parameters and grain-Zn in wheat cultivars. In crux, the current investigation suggests that Zn application; especially foliar sprays sustained higher grain content while Zincol cultivar in particular accumulated higher grain-Zn grown on calcareous soils applied with phosphate fertilizers. 1. Introduction Zinc (Zn) is an important micronutrient indispensable for achieving nutritional quality and productivity of cereal crop. The dietary disorder of micro-nutrients, especially Zn and iron (Fe) has affected two billion people around the globe while their acute deficiencies have caused 20% deaths of children below the age of five years (White and Broadley, 2009). In plants, Zn regulates gene expression to combat environmental stresses and its deficiency affects vegetative growth and consequently decreases grain yield (Cakmak, 2000). It is structural and functional component of hundreds of enzymes. Approximately 3000 proteins in higher animals and human possess Zn prosthetic groups (Tapiero and Tew, 2003). Furthermore, it is the only metal involved in all six classes of enzymes, i.e. oxide-reductases, transferases, hydrolases, lyases, iso- merases and ligases (Barak and Helmke, 1993). The major reason of Zn deficiency in cultivated soil is attributed to low solubility of Zn containing minerals in alkaline soil (Imran et al., 2016). Other factors that limit Zn supply in soil include low Zn bearing minerals, very low or high organic matter (< 0.5 to > 3%, respec- tively), soil alkalinity, water-logging, lime content, cations (Mg +2 , Na -1 , Ca +2 , etc.) and phosphate availability in soil. The deficiency in plants arising from low Zn content in soil is termed as primary defi- ciency while that ascending from other factors (e.g. its immobilization by high P application) is categorized as secondary deficiency (Sillanpää, 1982). In Zn deficient soils, it is applied in the form of chemical ferti- lizer to ameliorate its deficiency; however, Zn application to soil trig- gers various physicochemical reactions, ultimately decreasing its phy- toavailability (Aulakh and Malhi, 2005). The labile Zn in soil solution readily reacts with phosphate to produce insoluble Zn-phosphate, re- ducing its availability in soil and resulting in low accumulation (17–56%) by grain (Drissi et al., 2015). Barrow (1987) also attributed low Zn supply in soil to the higher availability of phosphate in soil. https://doi.org/10.1016/j.jcs.2019.102846 Received 2 April 2019; Received in revised form 14 September 2019; Accepted 17 September 2019 * Corresponding author. ** Corresponding author. E-mail addresses: sundasyousaf@gmail.com (S. Yousaf), sadamhussainuaf@gmail.com (S. Hussain). Journal of Cereal Science 90 (2019) 102846 Available online 17 September 2019 0733-5210/ © 2019 Elsevier Ltd. All rights reserved. T