Potassium plays a key role in the survival of plants under saline conditions in mitigating the adverse effects of sodium. The effect of application of potassium to soil (0, , and mmol/kg) and leaves ( and 9 mM) on tomato yield and quality under 3 salinity treatments (0, , and 15 dS m–1), using 2 salt-tolerant (Indent-1 and Nagina) and 2 salt-sensitive (Peto-86 and Red Ball) genotypes, was studied in a pot experiment. | Turkish Journal of Biology Turk J Biol (2014) 38: 208-218 © TÜBİTAK doi: Research Article Soil and foliar application of potassium enhances fruit yield and quality of tomato under salinity 1,2, 1 1 3 Muhammad AMJAD *, Javaid AKHTAR , Muhammad ANWAR-Ul-HAQ , Shakeel IMRAN , Sven-Erik JACOBSEN 1 Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan 2 Department of Plant and Environmental Sciences, Faculty of Sciences, University of Copenhagen, Tåstrup, Denmark 3 Department of Crop Physiology, University of Agriculture, Faisalabad, Pakistan Received: Accepted: Published Online: 2 Printed: Abstract: Potassium plays a key role in the survival of plants under saline conditions in mitigating the adverse effects of sodium. The effect of application of potassium to soil (0, , and mmol/kg) and leaves ( and 9 mM) on tomato yield and quality under 3 salinity treatments (0, , and 15 dS m–1), using 2 salt-tolerant (Indent-1 and Nagina) and 2 salt-sensitive (Peto-86 and Red Ball) genotypes, was studied in a pot experiment. Salinity decreased growth and yield of all genotypes; however, salt-tolerant genotypes maintained better growth and produced higher yield than the salt-sensitive genotypes across all salinity levels. Potassium application positively affected plant growth and yield, especially in salt-tolerant genotypes. Fruit quality characteristics (total soluble solids, titratable acidity, pH, dry matter %) were significantly improved by increasing salinity, except for fruit size. Soil and foliar K had nonsignificant differences between them; however, there were significant effects on the fruit quality, as all characteristics increased at higher K concentrations under salinity stress. It was concluded that the application of potassium increases yield and quality of tomato fruits in saline soil, and it could be