Calcium applications throughout fruit development enhance olive quality, oil yield, and antioxidant compounds' content

Abstract

BACKGROUND: Calcium is a preservative andfirming agent largely used in the table olive industry. Foliar applications of cal-cium (as calcium chloride, CaCl2) before harvest have been proposed in other fruits to increasefirmness and reduce physiolog-ical disorders or internal damage. However, there is still a shortage of information regarding the source, the concentration, thenumber, and the period of calcium application onto the canopy to get an effective response of olive quality. In this study, weaimed to investigate the effect of two concentrations of CaCl2foliar treatments (0.5% and 1.0%), applied at different stagesof fruit development (at the end of fruit set, end of pit hardening, and prior to harvesting), on olive quality for two varieties(‘Manzanilla de Sevilla’and‘Ascolanta tenera’), cultivated in two different geographical areas (Spain and Italy respectively).RESULTS: The calcium concentrations applied enhanced the fruit calcium content and decreased sodium and potassium. Theyalso improved the mechanical properties without modifying fruit morphology or cuticle thickness; nor did they cause phytotox-icity. Foliar treatments increased the oil content in the pulp (dry weight basis) and the amount of hydroxytyrosol, tyrosol, andoleuropein, among other phenols.