‘Honeycrisp’ is a popular apple cultivar, savored for its unique crispness and sweet taste. There is economic incentive to lengthen the period of fruit availability through postharvest storage, but several physiological disorders plague storage success, including soft scald (El-Shiekh et al., 2002; Tong et al., 2003). Soft scald is characterized by sharply demarcated irregular large brown lesions on fruit peel where tissue is slightly sunken and less firm (soft) to the touch (Plagge and Maney, 1924). Later in storage, pathogens can infest the affected tissue. Soft scald is often found concomitant with soggy breakdown, a fruit cortex, or flesh, disorder in which regions of brown water–soaked tissue have similarly sharply defined edges (Barker, 1930; DeEll and Ehsani-Moghaddam, 2010; Snowdon, 1990; Watkins et al., 2004).
The variation of susceptibility to soft scald among orchards has been partially attributed to preharvest factors, including climatic conditions during fruit growth (Lachapelle et al., 2013; Moran et al., 2009), orchard location and fruit mineral element concentration (Tong et al., 2003), preharvest plant growth regulators treatments, such as 1-methylcyclopropene (DeEll and Ehsani-Moghaddam, 2010), and fruit maturity at the time of harvest (Tong et al., 2003; Watkins et al., 2003). The information regarding these treatments or field conditions is neither controlled by nor necessarily available to storage and packing sheds when fruit are received. For this reason, quality and maturity metrics may be useful to assess the physiological condition of fruit when it arrives at storage sheds and are used to make storage decisions. These assessments include peel background color, flesh firmness, SSC, starch index (SI), and TA. In Washington, weather stations situated at numerous locations across the state (Washington State University AgWeatherNet <www.weather.wsu.edu>) could also allow assessment of climactic factors, including GDD and CH.
Quality and maturity metrics vary greatly at the time of harvest. Although these quality and maturity measurements tend to follow a predictable progression in storage [i.e., the gradual decrease in fruit firmness and TA (Jan et al., 2012)], the ratio of one metric to another is not always consistent among fruit harvests (Watkins et al., 2005). Quality and maturity measurements also indicate important physiological processes in the fruit, including maturity, ripening, and senescence, which have demonstrated relationships with soft scald/soggy breakdown (Watkins et al., 2003). Previous work has further demonstrated that preharvest climactic conditions can impact ‘Honeycrisp’ postharvest disorders, such as low temperature affecting diffuse flesh browning (Tong et al., 2016) and precipitation affecting soft scald (Moran et al., 2009). It is not clear whether quality and maturity metrics also consistently reflect aspects of underlying fruit physiology that increases susceptibility to soft scald and soggy breakdown, although soluble solids have been documented to be negatively correlated with soft scald incidence (Tong et al., 2016).
The goal of this study was to assess readily accessible field temperature data and easily measurable fruit quality/maturity metrics as tools for making storage decisions to reduce the incidence of soft scald in ‘Honeycrisp’ apples during storage. We hypothesized that results would indicate the potential for quality and maturity measurements to be used as metrics to predict the incidence of storage disorders soft scald at harvest or during storage.
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