Considering the importance of fertigation management in the hydroponic systems, the present study aimed to assess the frequency of fertigation and foliar application of potassium sulfate in a soilless culture of strawberries. Frequency of fertigation at three levels (1, 4, and 10 times per day) and foliar applications with potassium sulfate at three levels of concentration (0, 1, and 2 g L-1) were used. Results showed that by increasing the fertigation frequency to four times a day, the vitamin C, total acid, phenolic compounds, and antioxidant activity of fruits increased, and foliar application of potassium sulfate in all conditions of fertigation increased this parameter. Foliar application of 2 g L-1 potassium sulfate reduced the pH of the fruit juice compared to the plants without foliar application of potassium sulfate (0 g L-1). The frequency of fertigation and foliar application of potassium sulfate had a significant effect on the indices of fruit and sepal color change. Increasing the frequency of fertigation up to 4 times a day caused a significant increase in the dry weight of leaves and roots, the number of fruits, and total chlorophyll. The highest amount of leaf and root dry weight, early yield, and RWC were obtained in treating 2 g L-1 of potassium sulfate. It can be concluded that the management of fertigation and foliar spraying with potassium sulfate has a significant effect on the growth and development of the plant and the quality characteristics of the strawberry fruit.
