Preharvest Calcium Sprays at High Rates Increase Calcium Concentration Only in the Apple Skin Jesús Val, Emilio Monge, David Risco, and Alvaro Blanco Estación Experimental de Aula Dei (CSIC). Apartado 202. 50080 Zaragoza. Spain ABSTRACT Consumer demands for high quality fruit is leading to a greater awareness of the need to apply management techniques that enhances the quality of fruits by the fruit growing industry. Bitter pit is a disorder that greatly reduces the quality of fruits, and is related to calcium deficiency in the fruit. Generally, calcium sprays throughout the fruit growing season are recommended to prevent the development of bitter pit, but results are inconsistent. Thus, from 2004 to 2006 experiments have been conducted to study the absorption of Ca by the fruit, analyzing the effect of Ca sprays on the skin and flesh of fruits. The results obtained show that Ca treatments at high rates only affect the concentration of the element in the fruit skin, and that several sprays are needed to promote a prolonged increase in the concentration of this element on the skin, not affecting that in the fruit flesh. The concentrations of other elements (Mg and K) were not affected in any case. The absorption of Ca by the apple tree following the sprays was confirmed by foliar analysis, where increases in the concentration of the element were found. Keywords: Malus x domestica Borkh., calcium absorption, fruit analysis, bitter pit, mineral nutrition, calcium chloride, fruit skin, fruit flesh. Running head: Ca-sprays only increase Ca concentration in apple skin