ZINC REQUIREMENT FOR OPTIMUM GRAIN YIELD AND ZINC BIOFORTIFICATION DEPENDS ON PHOSPHORUS APPLICATION TO WHEAT CULTIVARS

Human bioavailable zinc (Zn) in cereal grains depends on contents of Zn and phosphorus (P) in grains because these two nutrients interact for their concentration in wheat grains. In the present study, a pot experiment was conducted to investigate the effect of various levels of P (0, 60 and 120 mg kg(-1) soil) and Zn (0 and 6 mg kg(-1) soil) on yield and grain Zn contents of four wheat cultivars i.e. Shafaq-2006, Auqab-2000, Pasban-90 and Pak-81. Grain yield of all tested wheat cultivars was increased by the application of Zn and P, but at variable rate. Calculations of deficiency stress factors for P and Zn confirmed higher demand of one nutrient at a higher application rate of the other nutrient. Concentration ratio of P to Zn in wheat grains was influenced by Zn application especially at higher rates of P application. Results showed that Zn application aiming at optimum grain yields and grain Zn concentration depends on genotypic variation in wheat cultivars and rate of P.