Grapevine (Vitis vinifera L.) is one of the economically important fruit trees with several valuable byproducts. Grapes are the world’s first and fourth largest fruit crop in terms of cultivated areas and fresh weight production., respectively. In terms of cultivated areas and production, Iran ranks 8th (215, 000 ha) and 10th (2.15 million tons) in the world, respectively, under the diverse ecosystems subject to irrigated, rainfed and deep-water conditions (FAO, 2012). Potassium is an essential element in plant nutrition and as one of the most prominent inorganic osmotic in plants, plays a vital role in many physiologically important processes of grapevine. Nevertheless, even as a major nutrient and the most abundant cation present in grape berries (Keller, 2010; Mpelasoka et al., 2003). By increasing the K supply to plant roots and leaves it is relatively easy to increase the K concentration of various organs (Marschner, 2012). Because potassium is a cofactor for several enzymes involved in fundamental metabolic processes, K affects basic plant metabolism, photosynthate production and translocation to sink organs (Cakmak, 2005). Given the economic importance of grape in Iran (specially some regions like Malayer), and role of K in plant growth and development, we did an experiment to evaluate the effect of different K treatments in the form of soil and foliar-applied on yield and some morphophysiological traits. In the present experiment, the foliar and soil application of potassium dramatically increased both quantitative and qualitative characteristics of ‘Sultana’ grapevine which could be considered as an applied nutrition program in vineyards. In conclusion, application of potassium fertilizer (Solupotasse and K-leaf) could improve grape morphological and physiological characteristics and enhance total yield of this important plant. Balanced fertilization and efficient K usage in combination with other nutrients not only contribute to sustainable crop’s growth,
