Edamame, or vegetable soybean, is a group of special cultivars of soybean harvested green at the R6 stage of development, or ≈80% pod fill, and used as a vegetable (Fehr et al., 1971). When harvested at the R6 stage, the flavor of edamame is nutty, sweet, buttery, beany, and superior in flavor to agronomic soybeans (Wszelaki et al., 2005). Consumers of edamame prefer bright green pods, two or more beans per pod, and large seed size (Montri et al., 2006). Edamame is eaten steamed in the pod as an appetizer, hulled as a side dish, or in salads or stir fry (Konovsky et al., 1994).
Edamame is a popular vegetable in Asian countries and is becoming increasingly popular in the United States. The increase in popularity can be attributed to the beneficial phytonutrients, high protein contents, increased consumer awareness, and taste of edamame (Duppong and Hatterman-Valenti, 2005; Zhang and Kyei-Boahen, 2007). The value of edamame purchased in the United States increased from $18 million in 2003 to $41 million in 2009 (Bernick, 2009; Soyatech, 2010).
Agronomic soybeans have high lipid content and are commonly used as an industrial source of oil. However, high oil content gives edamame an undesirable flavor (Konovsky et al., 1994; Wszelaki et al., 2005; Young et al., 2000). According to Hymowitz et al. (1972), agronomic soybeans' lipid content ranges from 145 to 230 g·kg−1 at dry maturity. Rao et al. (2002) reported edamame having between 130 and 156 g·kg−1 lipids at the R6 stage of development. These numbers agree with the data of Sikka et al. (1978), who reported that vegetable soybeans contain less fat than agronomic cultivars of soybeans. Hymowitz et al. (1972) reported that soybeans contain between 33.1% and 49.2% protein on a dry weight basis. Similarly, Hartwig and Kline (1991) reported averages of 39.8% and 46.9% protein for high and low oil soybean cultivars, respectively. Sikka et al. (1978) showed that edamame contains similar amounts of protein to agronomic soybeans.
Edamame reportedly grows well in the United States, but most is imported despite its growing popularity (Duppong and Hatterman-Valenti, 2005; Rao et al., 2002; Sanchez et al., 2005; Zhang and Kyei-Boahen, 2007). Although edamame cultivars have been bred for Virginia, few reports have evaluated commercially available cultivar yield potential in the mid-Atlantic United States (Bhardwaj et al., 1996; Sciarappa et al., 2007). Virginia and the mid-Atlantic United States have a robust snap bean industry that may be able to incorporate edamame production because of the similarities in culture, growth, yield, and equipment needed. Growing edamame in Virginia may help replace some of the 18,700 acres of tobacco (Nicotiana tabacum) production lost during the past decade [U.S. Department of Agriculture (USDA), 2009]. Bernick (2009) reported net returns of $600–$750 per acre for edamame grown for the Sweet Bean Company in Medina, OH. Ernst and Woods (2001) reported less favorable returns of $259 per acre with a break-even cost of production of ≈$1 per pound for hand-harvested edamame. The purpose of this study was to determine suitable cultivars for cultivation in Virginia and other areas of the mid-Atlantic United States based on yield, yield components, and quality.
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