Effect of Foliar Spraying with Different Sources of Potassium on Growth, Leaf Mineral Composition, Yield and Fruit quality of Picual Olive Trees.

Abstract

T HIS study was conducted during the 2018/2019 and 2019/2020 seasons on 12- year- old Picual olive trees grown in a private orchard located 182 kilometers south of Cairo on the Western Desert Road in Minia Governorate, and aimed to investigate the effect of foliar sprays with different potassium sources on growth, leaf mineral composition, yield and fruit quality. Foliar application potassium sources such as; potassium sulfate, potassium nitrate, potassium citrate and monopotassium phosphate were applied at 1.5 % and 3 % . Spraying is carried out three times immediately after the final fruit set (May), after hardening of the pit (first week of August) and after harvesting (October). The results showed that using the studied foliar potassium sources significantly improved vegetative growth, leaf mineral composition, fruit set, yield and fruit quality of Picual olive trees in comparison with control trees. Spraying of potassium nitrate at 3 % achieved the best results in terms of vegetative growth (shoot length - number of new laterals / shoot - number of leaves - leaf area) followed by spraying with potassium citrate at 3% in both seasons. As for leaf mineral content, nitrogen and potassium percentages were increased as a result of foliar application with potassium nitrate at 3 %. Picual olive trees were sprayed with potassium nitrate and potassium citrate at 3 % had the highest values in the flowering characteristics. Yield and fruit quality were significantly affected and the highest values were achieved in Picual olive trees sprayed with potassium nitrate at 3% followed by potassium citrate at 3% in both seasons.