Single-centered and Super Colossal Bulbs from Yellow Onion Cultivars

Abstract

<jats:p>Onion (<jats:italic>Allium cepa</jats:italic>) cultivars for commercial production in eastern Oregon and southwestern Idaho are evaluated annually in replicated yield trials conducted at the Malheur Experiment Station, Oregon State University, Ontario. Market demand has progressively called for larger bulb size and bulbs with single centers. At harvest onions were evaluated for maturity, number of bolters, and single centeredness. Cultivars showed a wide range of bulbs with only one growing point or “bullet” single centers, ranging from 1% to 57% in 2000, from 7% to 70% in 2001, and from 1% to 74% in 2002. The percentages of bulbs functionally single-centered for processing uses ranged from 18% to 88% in 2000, from 24.7% to 91.3% in 2001, and from 14.4% to 92% in 2002. Bulb yield and market grade were evaluated out of storage. Marketable yield after 4 months of storage varied significantly by cultivar from 643 to 1196 cwt/acre (72.1 to 134.1 Mg·ha<jats:sup>–1</jats:sup>) in 2000, from 538 to 980 cwt/acre (60.3 to 109.8 Mg·ha<jats:sup>–1</jats:sup>) in 2001, and from 583 to 1119 cwt/acre (65.3 to125.4 Mg·ha<jats:sup>–1</jats:sup>) in 2002. Averaging over cultivars, super colossal bulb size averaged 26%, 14%, and 10% in 2000, 2001, and 2002, respectively.</jats:p>

Yield, Quality, and Storage Characteristics of Onion Cultivars in the Columbia Basin of Washington in 2012–14

“…Redwing, which is another Bejo Seeds cultivar, was the only red cultivar with a higher than average firmness rating (3.6) ( Table 7). Single centeredness is known to be a heritable trait in onion (Cramer, 2006;Shock et al, 2005;Wall et al, 1996), so it is not surprising that the ANOVA for this study reported a significant cultivar effect for the percentage of functionally single-centered onions in these trials (Tables 6 and 7). The percentage of bulbs with functional single centers was 57.8% when averaged across years and cultivars (Table 7).…”

“…Each onion was cut in half (longitudinally) and the number of sprouted bulbs was recorded, and then cut again (latitudinally) to determine the number of bulbs with single centers or small multiple centers not exceeding 1 inch in diameter. Onion bulbs with single centers or small multiple centers are said to be ''functionally'' single centered (Shock et al, 2005). The numbers of bulbs with bacterial bulb rot and fungal neck rot were also recorded.…”

“…The percentage of bulbs with functional single centers was 57.8% when averaged across years and cultivars (Table 7). Based on the results of this study, most of the cultivars evaluated in these trials would not be a good choice for onion ring processing, since processors pay incentives to growers for delivering onions with at least 75% functionally single-centered bulbs (Shock et al, 2005). Only 14 of the 54 cultivars met this benchmark.…”

“…By contrast, 'Highlander' had the lowest average percentage of functionally single-centered bulbs at 2.8%, followed by 'Trekker' at 19.7%, and then 'Calibra' at 20.0%. Shock et al (2005) recommended that growers take care when choosing cultivars for singlecentered onion contracts, since only four of the 17 cultivars they evaluated over 3 years at the Malheur Experiment Station in Oregon consistently produced more than 74% functionally single-centered bulbs. The results of our trials, conducted more than a decade later, are similar and demonstrate that only a few of the long-day onion cultivars available today are a good choice for processing contracts that specify for functionally single-centered onions.…”

Onion Variety Response to Iris Yellow Spot Virus

“…cepae) diseases (Shock et al, 2000). Starting in 2000, two additional variety characteristics were evaluated: super colossal size bulbs (>4¼ inches diameter) and single-centered bulbs (Shock et al, 2005a).…”