To maintain fruit firmness and mitigate physiological alterations in a late season peach cultivar (Prunus persica ‘58GC-76’), environmentally friendly strategies including especial foliar calcium treatments, were developed. The innovation of these treatments consists of using an aqueous solution of the active matter (CaCl2) and a separate organic phase containing a concentrated adjuvant (tara gum) which confers to the final applied solution good characteristics of sticking and wettability, among others. This permits the spreading of calcium on the fruit surface and when environmental humidity increases, calcium solution can penetrate the fruit surface. This way of applying exogenous calcium, is only used in our laboratory so far. Conventional foliar applied calcium was not considered in this work because our previous results demonstrated their lack of effectiveness to mitigate physiological disorders in this commodity. Treatments at semi-industrial scale were conducted during 2014 and 2015 growing seasons. The very same pattern of treatments was applied to 58GC-76 peach orchards located in several sites of the ‘Bajo Aragón’ zone (NE Spain). The 58GC-76 variety suffers an emerging physiological disorder so called "corky spot" that has some similarities with vitrescent dark spot, which is affecting other late season peaches from the Protected Designation of Origin ‘Calanda’ in the same geographical region. The evolution of fruit nutrients (Ca, Mg and K), both in skin and pulp, demonstrated the effectiveness of calcium treatments during the two seasons in terms of increasing calcium concentration in both tissues. Regarding the evaluation of corky spot, a significant decrease in the severity and percentage of fruits affected was recorded in those fruits treated with calcium compared to control fruits which remained untreated.

This work has been funded by the project ‘Mejora de la calidad del melocotón de Calanda: material vegetal, técnicas culturales, conservación y comercialización’ and by the grant from de Spanish Ministry of Economy and Competitively ‘Mejora Genética de patrones Prunus y variedades de melocotonero’ (AGL2014-52063-R).

7 pags.- 3 Tabls.- 1 Fig. Article derived from a original aportation to authors to VIII International Postharvest Symposium (Cartagena, Spain. 21-24 June 2016). The definitive version is available at: https://www.actahort.org/index.htm

Peer reviewed