Pre-harvest Foliar Application of Calcium Chloride and Potassium Nitrate Influences Growth and Quality of Apricot ( Prunus armeniaca L.) Fruit cv. ‘Shahroudi’

The rapid ripening and fruit size are two important factors, which significantly influence the economy and marketability of apricot. Generally, the postharvest quality of fresh crops depends on the quality achieved at harvest time, which is influenced considerably by pre-harvest factors. Therefore, this study aimed to investigate the effect of foliar application of calcium chloride and potassium nitrate on the physical and biochemical attributes of apricot fruit. We evaluated the effect of foliar sprays of 0.5% or 1% calcium chloride (CaCl 2 ) and 1% or 2% potassium nitrate (KNO 3 ) on the yield and at harvest quality of apricot fruits cv. ‘Shahroudi’ during the 2019 and 2020 growing seasons. The experiment was conducted in a commercial apricot orchard located in Birjand, Iran. The results indicated that twice foliar spray of both chemicals at the pre-harvest stage affected most of the evaluated traits in both years. KNO 3 application at both concentrations significantly increased the length, width, and weight of apricot fruit and maintained total phenol content, vitamin C, and titratable acidity compared to the control. Interestingly, treated fruit with KNO 3 solution at both concentrations increased fruit width (150%), fruit length (160%), and fresh fruit weight (180%), compared to the control. Besides, KNO 3 (1% or 2%) and 1% CaCl 2 treatments significantly increased fruit firmness (25%) and calcium content (35%) of fruit pulp compared to the control. Overall, the results suggest practical multiple practical application of both chemicals (particularly KNO 3 ) at proper concentration and time during the growth season to improve the quality and increase the yield of apricot fruit ‘Shahroudi’ cultivar.