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S. Alan Walters

production method (bare soil/wheat straw mulch compared with black plastic) on garlic overwintering, bulb quality, and yield in southern Illinois. Materials and methods This study was conducted during 2005 and 2006 at the Southern Illinois University

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Daniel I. Leskovar, Shinsuke Agehara, Kilsun Yoo, and Nuria Pascual-Seva

, and average bulb size (g/bulb) were determined. During bulb sorting, 10 large bulbs per replication were sampled for bulb quality determination. Total soluble solids (°Brix) were measured with a digital refractometer from the onion juice squeezed by a

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William M. Randle

Field-grown `Granex 33' onions were subjected to four preplant calcium (Ca) treatments and evaluated for bulb quality and shelf-life over two seasons. Mature, cured bulbs were analyzed at harvest and after 1, 2, and 3 months of 4C storage. As preplant calcium increased, percentage of seed stems decreased, yield and soluble solids concentration increased, and then decreased, bulb firmness increased. Bulb pungency was unaffected by Ca fertility, except at the highest treatment. Percent bulb rot during storage first decreased with increasing Ca fertility, but then increased at the highest Ca treatment.

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David E. Kopsell and William M. Randle

Pungency and bulb quality changes during storage were evaluated using onion (Allium cepa L.) cultivars representing different storage abilities, pungency, and soluble solids content. Bulbs were harvested from greenhouse-grown plants, cured, and stored for 3 or 6 months at 5 ± 3 °C, 80% ± 5% relative humidity (0.8 to 1.1 kPa vapor pressure deficit). Prior to storage, and after each month of storage, bulbs were evaluated for pungency by measuring enzymatically formed pyruvic acid (EPY), soluble solids content (SSC), percent loss in mass (%ML), and loss of dormancy. Pungency differed among cultivars prior to and during storage. Among short-day (SD) cultivars, EPY either decreased or increased linearly with increased storage duration. Among intermediate (ID)- and long-day (LD) cultivars, EPY decreased linearly or quadratically during storage. Short-day cultivar SSC increased, then decreased quadratically during storage, while ID and LD cultivar SSC decreased linearly over time. Percent loss in mass increased linearly during storage among all cultivars, although SD cultivars exhibited greater %ML than did ID or LD cultivars.

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Pablo Marinangeli and Néstor Curvetto

Scaling is a common commercial technique to propagate Lilium. The present research work evaluated the impact of genotype, traumatic acid (TA), and initial bulb quality on bulblet production by scaling propagation. Genotypes used were: L. longiflorum Thunb. `Snow Queen', L. lancifolium Thunb., one Oriental hybrid (L. × `Stargazer'), and four Asiatic hybrids (L. × `Enchantment', L. × `Connecticut King', L. × `Sunray', L. × `Cote d'Azur'). The genotypes showed a wide variability in the number (1.1-2.6 bulblets per scale) and biomass (83-295 mg per bulblet) of bulblet production. The same variability was exhibited after treatment with TA, which produced an increase of 20% to 40% in the number of bulblets per scale and also a significant increase in their fresh mass (20% to 60%). Using poor quality L. × `Cote d'Azur' bulbs adversely affected the biomass and number of bulblets produced on the scales, and this effect was not overcome with TA treatment. Chemical name used: 10(E) dodeca-l,12-dicarboxylic acid (traumatic acid).

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Jagtar Singh and Christopher S. Cramer

Onion growers in New Mexico often withhold irrigation for overwintered onion varieties during the months of December and January. This study was initiated to determine if this deficit irrigation program is detrimental to onion bulb quality. Twelve short- and intermediate-day onion cultivars, which differed in their maturity, were seeded in Sept. 2004 in Las Cruces, N.M. Once plants were established, 12 plots of each cultivar were not irrigated during the months of December and January (dry treatment), while the same number of plots was irrigated during these months (wet treatment). Once a plot had 80% of the plants with tops down, all bulbs were harvested, cured, and data on date of harvesting, bulb diameter, bulb height, firmness rating, number of centers, scale number, and scale thickness of first and third fleshy layers were collected. For most of the bulb traits measured, there was no difference between the two irrigation treatments for the cultivars tested. For the earliest-maturing cultivars, bulbs grown in the dry treatment had on average more fleshy scale layers than the bulbs grown in the wet treatment. For later-maturing cultivars, bulbs grown in the dry treatment had more growing points (centers) per bulb than the bulbs grown in the wet treatment. For the latest-maturing cultivars, average fleshy scale layer thickness was greater for bulbs grown in the dry treatment. From this work, a winter deficit irrigation program appears to be detrimental to the percentage of single-center bulbs for later-maturing, autumn-sown onion cultivars.

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Neel Kamal and Christopher S. Cramer

Onions grown in New Mexico are currently harvested manually at 80% tops down (TD). Mechanical harvesting is a matter of urgency for growers in order to remain competitive and to reduce their cost and time. The objective of this study was to find the effect of different harvest stages on bulb quality. Twelve different onion cultivars were sown in Feb. 2004 in Las Cruces, N.M. The experiment was laid out in split-plot design with four harvest treatments based on physiological maturity—20% TD, 80% TD, 1 week after 80% TD, and 2 weeks after 80% TD as whole plots, with cultivars as sub-plots. After curing, data on harvest date, bulb diameter, height, firmness, number of growing points, average center diameter, fleshy scale number, and scale thickness were collected. Maximum number of scales was observed when bulbs were harvested 2 weeks after 80% TD, while average scale thickness was greatest when bulbs were harvested 1 week after 80% TD. Significant treatment by cultivar interaction was observed for bulb firmness. Cultivars Cimarron, Sierra Blanca and NMSU 04-52-2 produced firmer bulbs in all treatments, while NuMex Casper, NuMex Jose Fernandez and NuMex Centric produced firmer bulbs than others, only at 20% TD. Maximum bulb firmness was observed in NMSU 04-28 and NMSU 03-52-1 than others, when harvested 1 or 2 weeks after 80% TD. Overall, bulbs harvested 1 to 2 weeks after 80% TD exhibited firmer bulbs with more scales and greater scale thickness.

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Pablo Marinangeli and Nestor Curvetto

Micropropagation is an advantageous technique for commercial Lilium propagation. The aim of this work was to evaluate the impact of genotype, traumatic acid [TA, 10(E) dodeca-1,12-dicarboxylic acid] treatment and an initial bulb quality on lily in vitro propagation. Genotypes were: L. longiflorum Thunb. `Snow Queen', L. lancifolium Thunb., one Oriental hybrid (L. × `Stargazer'), and four Asiatic hybrids (L. × `Enchantment', L. × `Connecticut King', L. × `Sunray', L. × `Cote d'Azur'). Assays were done with good-quality bulb genotypes—chosen by water content, sprouting degree, and appearance—with exception of L. × `Cote d'Azur', where poor-quality bulbs were also included. Surface-sterilized 3-mm scale bulb sections where cultured in MS medium with 100 mg·l–1 myo-inositol, 0.4 mg·l–1 thiamine·HCl, 0.1 mg·l–1 NAA, and 3% sucrose and 0.8% agar, pH 5.7. Cultures were kept in darkness at 25°C during 8 weeks. One μM TA was used to immerse half of the explants during 1 hr before culturing. Genotypes showed a wide variability in bulblets' number (1.7–2.9 bulblets per explant) and biomass (55–147 mg per bulblet). The same variability was observed after TA treatment, which produced an increase in bulblets number per explant (14% to 59%) and also a significantly augmented their fresh mass (9% to 42%). Poor-quality L. × `Cote d'Azur' bulbs adversely affected both biomass and number of bulblets produced on the scale sections, which was not overcome with TA treatment. These results suggest the convenience of TA application in Lilium micropropagation protocols on good-quality bulbs, irrespective to the genotype source.

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Timothy W. Coolong and William M. Randle

, Coolong et al., 2004 ; Fenn and Feagley 1999 ). Hence, little is known about the effects of Ca on bulb quality attributes. In addition to improving bulb firmness, CaCl 2 applications have been correlated to decreases in bulb pungency in greenhouse

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Michael J. Havey, Marita Cantwell, Meriel G. Jones, Richard W. Jones, Norman E. Schmidt, John Uhlig, J.F. Watson, and Kil Sun Yoo

Onion pungency is a major quality attribute with many consumers demanding less pungent onions. In recent years, some growers and retailers have attempted to measure pungency of onions produced in different regions to guarantee a desired level of pungency. However, there are few data on the variability among laboratories using standardized protocols to estimate relative levels of pungencies. Onion cultivars were grown in replicated trials at three locations. Random samples of bulbs from each experimental unit were harvested and shipped to at least three cooperating laboratories, each of which measured soluble solids content (SSC) and pungencies using the same techniques. As expected, cultivars and environments showed significant (P < 0.001) differences. For all three trials, laboratories were a highly significant source of variation (P < 0.024 to 0.001) for measurements of SSC and pungency. Therefore, one cannot make recommendations on relative pungencies of the same lots of onions measured by different labs. The onion research community must identify specific procedures to reduce variation among laboratories to develop a more repeatable standardized assay for the measurement of onion pungency.