Timing and Rate of Foliar Potassium Application to Improve Yield, Fruit Size and Quality Attributes of Pomegranate: Based on Data Generated in Field Experiments Conducted in Iran and Egypt

Abstract

ABSTRACT It is proven that potassium (K) plays a key regulatory role in many physiological processes of plant growth and that K fertilization can improve the yield and quality attributes in fruit crops. This study was carried out to evaluate the effect of timing and various concentrations of foliar sprays of potassium sulfate, during fruit growth and maturation, on yield and quality of pomegranate fruit in Iran and Egypt, which have different pomegranate production systems. In Iran one, two or three sprays of 1% or 2% K-Leaf® (a high grade foliar potash booster) was used, and in Egypt a single spray of either 10 or 20 kg/ha, and two sprays of 10 and 20 kg/ha K-Leaf® were applied. Results showed that in both experiments in Iran and Egypt, foliar K treatments increased total and marketable yield of pomegranates, as well as fruit weight and size, flavor index (the ratio of total soluble solids/total acid). The treatments also improved the fruit’s peel and aril color compared to the non-treated control plants. Results also demonstrated that multiple potassium sprays (two or three applications) were more effective than applying higher concentrations; as in many cases, there were no significant differences between 1 and 2% concentrations of K fertilizer in treatments with same number of applications (one, two or three sprays). Although three sprays of 2% K-Leaf® were the most effective treatments, it can be concluded that three sprays of 1% K-Leaf®) is probably more economically sound for use in pomegranate orchards.