Tomato (Solanum lycopersicum L.) is one of the most important edible berry crops belonging to the Solanaceae family (Iftikhar et al., 2021). It is one of the most consumed and economics crops worldwide (FAO, 2020). Tomato is considered to be of high nutritional value because it contains a large number of components that are important for the human body (Dzakhmisheva et al., 2021), such as micronutrients (Gholami et al. 2021), sugars, vitamins (Zhu et al., 2021) and many organic acids (Yan et al., 2021). Tomato plants are widely cultivated in Iran, but various biological and nonbiological conditions restrict their growth. Plants are exposed to a wide range of ambient temperatures during the course of a day or a season. Increasing the temperature 10–15 °C above the optimum temperature is generally termed as heat stress or heat shock which can affect the plant growth and development (Wahid et al., 2007). Tomato plants are sensitive to high temperatures and heat stress can stimulate flower abscission (Camejo et al., 2005) and limit the fruit yield (Driedonks, 2018). High temperature dose not just reduce the flowering and fruit set of the plant, but also affects the development and maturity of the fruit and consequently reduces the crop yield. Changing the temperature to suboptimal temperature conditions significantly affected the reproductive growth of the tomato (Driedonks, 2018), and causes loss in fruit setting and yield (Sato et al., 2000). Mineral nutrition of plants plays a critical role in increasing plant resistance to environmental stresses (Marschner, 2012). Among the mineral nutrients, Potassium (K) plays a crucial role in plant growth and development and survival of crop plants under environmental stress conditions. K is essential for many physiological processes, such as photosynthesis, translocation of photosynthates into sink organs, maintenance of turgidity and activation of enzymes under stress conditions (Hawkesford et al., 2012). Soil fertilization is
