259 Prediction of Apple Fruit Quality Using Preharvest Mineral Nutrients E. Fallahi and B. Fallahi University of Idaho, Research and Extension Center, Parma, Idaho USA J.B. Retamales Laboratorio de Ecofisiología Universidad de Talca, Talca Chile C. Valdés Soquimich Comercial, Santiago Chile S.J. Tabatabaei The University of Tabiriz, Tabriz Iran Keywords: Malus x domestica, postharvest, storage, nutrient balance Abstract Leaf mineral analysis has been a useful tool for diagnosis of apple tree (Malus x domestica Bork.) deficiencies for several decades. However, leaf minerals alone cannot precisely predict many of the fruit postharvest disorders. Therefore, fruit analysis alone or in combination with leaf analysis are used for a more precise prediction of fruit quality. The authors have been developed several prediction models for prediction of apple fruit quality over the last several years. Models developed within a given year, can predict apple fruit quality attributes for that year, but may not strongly predict quality attributes in different years. To solve this problem, a ranking of major minerals, such as calcium (Ca) and nitrogen (N) has been developed that can predict apple fruit quality within a year and between years. In these trials magnesium (Mg) infiltration was also used into fruit to artificially induce bitter pit, and based on the degree of bitter pit occurrence, predict the potential for postharvest bitter pit development. In these studies, increase in fruit N was always negatively associated with fruit yellow or red color and increase in fruit Ca was negatively associated with bitter pit but was positively associated with fruit firmness. Apple fruits with greater N concentrations had greater ethylene concentrations and respiration rates. In this article, an overview of prediction studies from these authors and other researchers are discussed. INTRODUCTION Although leaf analysis is a diagnostic tool for optimizing mineral nutrition in fruit trees, it correlates weakly with fruit quality, thus fruit analysis is more useful in estimating quality (Sharples, 1980; Fallahi et al., 1985) and storage disorders (Bramlage et al., 1980; Sharples, 1980). Mineral analyses of leaf and fruit tissues have become more popular in recent years because of the advances in analytical equipment, allowing multi- element analyses in a fraction of the time and cost traditionally associated with mineral analyses. Understanding relationships between postharvest quality and preharvest mineral nutrients and orchard practices makes various management decisions, such as storage strategies, easier. An early identification of fruit likely to be low in soluble solids concentration (SSC) or titratable acidity (TA) after storage also will assist in developing marketing strategies. A perfect identification and prediction of fruit quality is neither possible nor necessary. If the apple industry can predict and categorize fruit likely to be low or high in some postharvest quality attributes before storage, profit can be enhanced. RESULTS AND DISCUSSION Quality Attributes to be Predicted Fruit size, color, potential for storage breakdown, bitter pit, stem-end cracking, russetting, and lenticel breakdown are often the commercially important attributes that Proc. V th IS on Mineral Nutrition of Fruit Plants Eds. J.B. Retamales and G.A. Lobos Acta Hort. 721, ISHS 2006