Salinity stress is one of the most important abiotic stresses, affecting crop’s productivity. Potassium plays a major role in the survival of plants under salinity stress conditions in reducing the adverse effects of sodium. A pot experiment was conducted, aiming to study the effect of foliar application of potassium on the growth and yield of tomato (Lycopersicon esculentum L.) under salinity stress”. The research was performed under two factorial arrangements in a Randomized Complete Block Design (RCBD) and replicated three times at ornamental nursery, department of Horticulture, The University of Agriculture Peshawar during summer, 2022.  The levels of potassium for foliar sprays were 0, 0.4, 0.6 and 0.8 ml L^-1. Potassium sulphate was used as a source of potassium. The salinity levels of 60 and 90 mM sodium chloride (NaCl) including control were studied. All studied attributes were significantly affected by foliar applied potassium and salinity stress. Interaction between potassium levels and salinity stress were significant for leaves plant^-1, leaf area, fruits plant^-1, fruit weight and fruit diameter. Foliar application of potassium significantly increased the growth and yield of tomato. Maximum plant height (63.55 cm), leaves plant^-1 (19.77), leaf area (0.642 m²), fruits plant^-1 (7.77), fruit weight (62.46 g), fruit diameter (54.00 mm), fruit firmness (2.34kg cm^-2), ascorbic acid content (14.50 mg 100g^-1of fresh fruit weight) were recorded at the highest level of potassium (0.8 % potassium). Salinity stress reduced the growth and yield of tomato while increased fruit firmness.  In case of salinity maximum plant height (63.50 cm), leaves plant^-1 (20.41), leaf area (0.546 m²), fruits plant^-1 (7.66),  fruit weight (59.94g), and fruit diameter (54.05mm) while minimum fruit firmness (2.09 kg cm^-2) were recorded in control where no salt stress was applied. Data regarding interaction revealed that maximum leaves plant^-1(24.00), leaf area (0.655 m²), fruits plant^-1(9.33), fruit weight (67.58g) and fruit diameter (61.40mm) were observed with the application of 0.8 % of potassium in control conditions where no salinity was imposed. It is concluded that salt sensitive variety of tomato (Rio Grande) could not be grown under salt stress conditions. However, foliar application of Potassium Sulphate (0.8 ml L^-1) enhanced growth and yield of tomato under salt stress and it could be adopted as an effective practice to grow tomato variety (Rio Grande) under salinity stress conditions.

Keywords: Foliar application, Growth, Potassium Sulphate, Salinity, Tomato (Rio Grande).