Orchard factors affecting postharvest stone fruit quality

Although stone fruit quality cannot be improved, only maintained, after harvest, little research has been conducted on the influence of preharvest factors on stone fruit postharvest quality and potential postharvest life. We believe that the maximum fruit quality for each cultivar can be achieved only by understanding the roles of preharvest factors in fruit quality. This article reviews the influences of orchard factors, such as mineral nutrition, irrigation, crop load, and fruit canopy position on fruit quality, market life potential, and internal breakdown (IB). The literature indicates that quality, market life, and IB are related to preharvest factors. Thus, there is a need to continue studying these factors to deliver high quality fruit to the consumer. In recent years the production of stone fruits has increased rapidly, but consumption has remained low at -2.7 k g . y e d per capita for nectarines and peaches and -0.6 kg.yearl per capita for plums and fresh prunes (U.S. Dept. of Agr., 1994). Surveys conducted to explain the low rate of consumption of stone fruits found that consumers were botheredmainly by lackofflavorand IB problems(Bruhnetal., 1991). Since production is still increasing, more attention must be given to the production and delivery of high-quality stone fruits to increase consumer demand. Studies have associated high consumer acceptance with high soluble solids concentration (SSC) in many commodities (Kader, 1994; Parker et al., 1991), but there are more factors involved, such as acidity (Kader, 1994; Peterson and Ivans, 1988), SSC/acidity ratio (Kader, 1994; Nelson, 1985; Rodan, 1988), phenolics (Robertson and Meredith, 1989), and volatiles (Romani, 1971). In peach (Pruws persica (L.) Batsch], plum (Prumrs salicina Lindel.), and nectarine [Prunus persica var. nectarine (L.) Batsch], there is limited information on the relationship between consumer acceptance and ripe fruit chemical composition (Claypool, 1977; Kader, 1994; Mitchell et al., 1990). Since we do not have enough information on this subject, we are not able to propose any quality standards without detailed studies to support them (Crisosto, 1994a). One important complex cause of quality deterioration and consumer complaints in apricots (Prunus armeniaca L.), peaches, nectarines, plums, and prunes (Pmnusdamesrica L.) is the presence of flesh browning, flesh mealiness, darkened pit cavity, flesh translucence, red pigment accumulation (bleeding), and loss of flavor (Crisosto et al., 1995a, 1995b; Mitchell and Kader, 1989). These symptoms result from IB, which is also called chilling injury, dry fruit, or woolliness. 1B normally appears during prolonged cold storage andor after ripening at‘room temperature following cold storage. This disorder is the main limitation to long-term storage and shipping to distant markets for IB-susceptible cultivars. There is little published information on the possible influence of preharvest factors on IB incidence (Claypool, 1977; Saenz, 1991). During the past I O years, increased research emphasis has been