EFFECTS OF ZnSO4 ON GROWTH, SOME KEY PHYSIOLOGICAL PROCESSES AND IONIC HOMEOSTASIS OF DIFFERENT BREAD WHEAT (TRITICUMAESTIVUM L.) GENOTYPES UNDER SALINITY STRESS

Salinity stress is one of the most threating abiotic stresses limiting agricultural crop production worldwide by affecting crop growth and physiological processes and ion balance. Exogenous application of various chemicals can enhance the crop production by improving growth and physiological parameters and reducing specific ion toxicity. The purpose of the present study was to investigate the ameliorative role of Zn in wheat during salinity stress by bringing more land under cultivation to improve wheat production. A hydroponic experiment was performed to assess the rectifying effect of increased doses of zinc from recommended dose in different salinity levels i.e., moderate to strong salinity. Two doses of zinc (2 mM, 4 mM) and two levels of NaCl (70 mM, 140 mM) along with control were used to screen the twelve genotypes of wheat. Salinity stress decreased the growth parameters i.e., shoot and root length, fresh and dry biomass maximum up to 45% when the recommended dose of zinc was applied. Increasing the dose of zinc improved the growth attributes of seedling up to 21% under moderate to strongly saline conditions. In the same way, high doses of zinc increased the RWC, MSI and K+ concentration up to 24%, 17% and 45% respectively decreasing the Na+ conc. in plant aerial parts up to 27%. K+ ion conc. was increased by increasing the zinc application rate showing synergistic effect of Zn with K+, was improved by increasing the zinc dose showing increasing the tolerance of seedling against salinity stress. Two varieties i.e., Faisalabad-08 and Sehar06 performed the best in terms of salinity tolerance and zinc use efficiency under saline conditions. It was concluded from the results that higher doses of Zn fertilization along with salt tolerant varieties can significantly increase the crop biomass and grain yield by improving growth and physiological processes and reducing Na+ toxicity under saline conditions.