EFFECT OF FERTILIZATION AND STORAGE CONDITIONS ON POSTHARVEST QUALITY OF ZACATECAS-TYPE PEACH (PRUNUS PERSICA (L.) BATSCH)

To study the relationship of fertilizer formulation, method of application, and cold storage conditions to the fruit quality and sensitivity to internal browning of local race Zacatecas-type peach, research was done in an orchard with ten-year-old trees that had been managed under minimum tillage for five years. Three formulations of soil applied NPK were compared, each of them with o without foliar supply (F) of Ca, Mg, B and Mo. The variables evaluated were firmness, color, titratable acidity, total soluble solids, ethanol, acetaldehyde, total phenols, polyphenoloxidase, and phenylalanine ammonia-lyase. Soil and foliar fertilizers with lower N content increased pulp firmness. This effect persisted during storage at both 5 °C and room temperture. Soil and foliar applications of fertilizers with higher N content reduced fruit firmness, while those with higher K content increased the fruit content of phenols. Foliar fertilization improved external fruit color and reduced the activity of phenylalamine ammonia-lyase and polyphenoloxidase. Both soil and foliar applications significantly changed content of total soluble solids, malic acid and ethanol. Applications with higher N favored snthesis of acetaldehyde. Fruits stored both under refrigeration and at room temperature ripened normally.