The production and quality of tomato fruit is directly related to the quality of the water used for irrigation and the adequate supply of nutrients, especially potassium and calcium. This work was carried out at the Department of Environmental and Technological Sciences of the Federal Rural University of the Semi-Arid (UFERSA) in Mossoro, RN, with the aim of evaluating the cultivation of tomatoes (Lycopersicumes culentum Mill) in a protected environment, using irrigation with saline water and fertigation with different potassium: calcium ratios. The experimental design used was randomized blocks, in a 5 x 4 factorial scheme, with four replications. The experiment was carried out in a protected environment using coconut fiber substrate. The treatments were formed by combining five ionic ratios of potassium and calcium using standard solutions for each crop.