Rabbiteye blueberries (Vaccinium virgatum) are more resistant to mechanical harvesting and have been MH for fresh market for many years. Mainland et al. (1975) studied the quality of HH highbush blueberry (Vaccinium corymbosum) cultivars compared with MH fruit using side–slapper finger harvest technology from that era; they reported that MH fruit were softer than HH fruit, resulting in significantly higher losses and increased decay during storage. Since then, several studies have evaluated MH as newer harvest technologies and cultivars became available. The older, side–slapper finger units have been replaced in favor of dual vertical-shaft vibrating finger units (now known as continuous canopy shakers) (Mainland, 1993). Fruit of early yielding, southern highbush blueberry cultivars grown in low-chill regions in the United States were considered too susceptible to mechanical injury to be MH (Takeda et al., 2008). Currently, southern highbush blueberries are MH only late in the season typically for the frozen processing market with a value ranging from $0.50/lb to $1.20/lb. In contrast, Florida blueberry (Vaccinium sp. and hybrids) growers sold early season fruit for fresh market at almost five times the price for the processing market [$5.56/lb (Perez and Plattner, 2012)]. Consumer demand for blueberries continues to rise, in part due to reports that they have some of the highest antioxidant properties among fresh fruit (Clark et al., 2002; Connor et al., 2002; Prior et al., 1998; Sellappan et al., 2002). This has led to significant increases in acreage of southern highbush blueberry cultivars in Florida and other southeastern states to obtain the high, early season prices. In 2011, Florida growers produced the largest yield on record, estimated at 21.4 million pounds (Perez and Plattner, 2012); in 2012, total harvested area in Florida reached an all-time high of 4500 acres (U.S. Department of Agriculture, 2013).
Labor cost and availability are primary concerns of southern highbush blueberry growers, prompting them to explore the potential for using mechanical harvesters for fresh market (Fonsah et al., 2008). However, for MH to become viable, these early season, high-value fruit must be of sufficiently high quality to fetch fresh-market prices; the price received for the process market is not high enough to offset the savings from reduced labor. Blueberries destined for fresh markets must maintain acceptable quality for 2 to 3 weeks after harvest to meet market demands.
Identifying cultivars that maintain good postharvest quality during transport and marketing is critical to a successful MH program. Firm fruit texture is one of the most critical characteristics because it improves the probability that fresh packed blueberries will be received by buyers with acceptable quality. NeSmith et al. (2002) reported that MH rabbiteye blueberry lost 20% to 30% firmness as compared with HH fruit. The University of Florida’s breeding program has produced advanced selections of southern highbush blueberry hybrids with higher firmness, among other key characteristics (Lyrene, 2002). Blueberry growers could potentially realize significant cost savings if cultivars and equipment were developed or identified that would allow MH for fresh market. This could dramatically increase production efficiencies, and potentially revolutionize the fresh-market blueberry industry.
The objective of this research was to determine the potential for MH southern highbush blueberry cultivars that are destined for fresh market. Selected blueberry cultivars and breeding lines were harvested by hand or with a commercial mechanical harvester during two successive seasons and fruit quality attributes were assessed following harvest, commercial packing, and storage.
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