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Muharrem Ergun, Steven A. Sargent, and Donald J. Huber

Grape tomatoes (Lycopersicon esculentum Mill. `Santa') harvested at light-red (>90% color) and full-red stages were treated with 1 μL·L–1 1-methylcyclopropene (1-MCP) for 24 hours at 20 °C and stored at 20 °C. After 1 day of storage, fruit harvested at light-red stage treated with 1-MCP had a 56% lower respiration rate than untreated fruit. By day 7, respiration rates of the two treatments had converged at about 2 mL·kg–1·h–1. Ethylene production of light-red stage tomatoes treated with 1-MPC was 24% lower than untreated during storage, with rates converging by day 11. For fruit harvested full-red, 1-MCP had similar effects on respiration and ethylene production, although convergence occurred earlier, by day 5. Subsequent tests were conducted only with fruit harvested at full-red stage, since fruit harvested at the light-red stage had lower soluble solids content (4.3%) than fruit harvested at the full-red stage (5.5%). Several combinations of 1-MCP concentrations and exposure times were applied at 20 °C: 1 μL·L–1 for 24 h, 5 μL·L–1 for 6 or 12 h, 25 μL·L–1 for 6 or 12 h, and 50 μL·L–1 for 6 or 12 h; following the respective pretreatment fruits were stored at 20 °C. 1-MCP pretreatment extended marketable life by 1 d, irrespective of pretreatment regime, where untreated and pretreated fruit remained marketable (<15% of fruit soft, decayed and/or shriveled) for 6 and 7 d, respectively. However, 1-MCP did not affect whole fruit firmness, epidermal color, internal color, soluble solids content (6.5%), total titratable acidity (0.64%), or pH (4.3). In a third test simulating commercial handling procedures, full-red harvested tomatoes were treated with 1 μL·L–1 1-MCP for 24 h at either 13 or 20 °C, stored for 4 d at 13 °C, and then transferred to 20 °C. Under these conditions, marketable life for untreated and 1-MCP-treated tomatoes was 7 and 8 d, respectively.

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Eunkyung Lee, Steven A. Sargent, and Donald J. Huber

Roma tomatoes (‘BHN 467’) were hand-harvested at mature-green color stage and treated with ethylene (100 μL·L−1 at 20 °C and 90% relative humidity) until reaching breaker (<10% red), pink (30%–60% red), or light-red ripeness stage (60%–90% red). Individual fruit at each ripeness stage were subjected to double impacts over the locule using a pendulum-impact device with a force equivalent to two 40-cm drops, followed by ripening at 20 °C. Fruit exhibited most noticeable increases in respiration and ethylene production within 1 hour and 1 day after impact, respectively. After 24 hours, respiration rates increased 40%–60% regardless of ripeness stage, while ethylene production in impacted breaker-stage fruit increased 3-fold (to 6.7 μL·kg−1·h−1). Fruit impacted at breaker stage softened 2 days earlier compared with non-impacted breaker fruit. Fruit impacted at all ripeness stages had higher electrolyte leakage and polygalacturonase (PG) activity during ripening than non-impacted fruit. After 6 days, electrolyte leakage in fruit impacted at light-red ripeness stage was 23% higher than non-impacted fruit; PG activity in breaker fruit increased 40% at 10 days over non-impacted fruit. No changes were observed for soluble solids content, total titratable acidity, pH, or sugar/acid ratio from impacts, independent of ripeness stage.

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Kathryn Gunderson, Steven A. Sargent, Daniel J. Cantliffe, Steven G. Jacob, and George J. Hochmuth

To remain competitive for federal and state funding, state cooperative extension services must proactively incorporate issues programming and performance-based budgeting. State major program (SMP) design teams, which provide linkages between clientele groups and the research base, must conduct needs assessments to adjust to this new atmosphere of accountability. A case study illustrates how one Florida SMP (FL107, vegetable production, harvest, handling and integrated pest management in Florida) restructured its design team to become more flexible and proactive to target a wider range of outcomes. While still in the implementation phase, this model has already resulted in improved communication within the organization, better addressing extension needs at county level while facilitating reporting at the state level.

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Marcelo A.G. Carnelossi, Edinaldo O.A. Sena, Adrian D. Berry, and Steven A. Sargent

Blueberry is widely grown around the world, and the United States is the leading producer. A strategy to maintain fruit quality during commercial handling is rapid cooling using the forced-air system. Hydrocooling (HY) is an effective cooling method widely used for many crops and has potential as a cooling method for blueberry. The objective of this study was to compare the cooling efficiency of conventional forced-air cooling (FA), the current commercial method, with immersion HY alone or HY in combination with FA (HY + FA), and to determine effects on blueberry fruit quality during subsequent cold storage. ‘Emerald’ and ‘Farthing’ southern highbush blueberry were commercially harvested and packed into plastic clamshell containers. FA was accomplished by simulating commercial conditions using a small-scale unit within a cold room at 1 °C/80% relative humidity (RH) until 7/8 cooling was achieved (27 minutes). For HY, fruit in clamshells (125 g) were immersed in chlorinated ice water (200 ppm free Cl−1, pH = 7.0) and 7/8 cooling occurred in 4 minutes. For HY + FA, fruit were 7/8 hydrocooled then transferred to FA for 30 minutes to remove free water from the fruit. After the cooling treatments, clamshells were evaluated weekly for selected quality parameters during 21 days storage at 1 °C. For HY treatment, the 1/2 cooling time was 1.13 minutes for ‘Emerald’ and 1.19 minutes for ‘Farthing’, whereas for FA treatment, the 1/2 cooling times were 4.5 and 6.8 minutes, respectively. For ‘Farthing’, cooling method did not affect fruit firmness; after 21 days, there was a slight softening in fruit from all treatments. However, ‘Emerald’ fruit cooled by HY + FA were softer than those from either HY or FA after 14 days of storage. For all cooling methods ‘Emerald’ was less acidic (0.3% citric acid) and was sweeter [10.2% soluble solids content (SSC)] than ‘Farthing’ (0.6% citric acid, 9.4% SSC). There were no differences in bloom among cooling methods. Bloom ratings for ‘Emerald’ remained >4.5 (70% to 80% coverage) whereas that for ‘Farthing’ cooled by HY or HY + FA was 3.7. Anthocyanin concentration in ‘Emerald’ fruit from HY + FA cooling method decreased by 33% during 21 days of storage, whereas that for ‘Farthing’ remained constant (8.3 mg cyanidin-3-Glicoside/g) irrespective of treatment during storage. Compared with ‘Farthing’, ‘Emerald’ was more sensitive to HY, where ≈15% of fruit developed visual skin breaks (split) after 7 days storage. HY shows potential as an alternative method to rapidly and thoroughly cool southern highbush blueberries such as ‘Farthing’, thus, maintaining fruit quality, while introducing a rinsing and sanitizing treatment. HY needs to be tested on commercial cultivars to determine the incidence of fruit splitting.

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Celso L. Moretti, Elizabeth A. Baldwin, Steven A. Sargent, and Donald J. Huber

Tomato (Lycopersicon esculentum Mill.) fruit, cv. Solar Set, were harvested at the mature-green stage and treated with 50 μL·L-1 ethylene at 20 °C. Individual fruits at the breaker stage (<10% red color) were dropped onto a solid surface to induce internal bruising. Dropped and undropped fruit were stored at 20 °C until red-ripe, at which time pericarp, placental, and locule tissues were excised. Tissues from dropped tomatoes were examined for evidence of internal bruising and all tissues were analyzed for selected volatile profiles via headspace analysis. Individual volatile profiles of the three tissues in bruised fruit were significantly different from those of corresponding tissues in undropped, control fruit, notably: trans-2-hexenal from pericarp tissue; 1-penten-3-one, cis-3-hexenal, 6-methyl-5-hepten-2-one, cis-3-hexenol and 2-isobutylthiazole from locule tissue; and 1-penten-3-one and β-ionone from placental tissue. Alteration of volatile profiles was most pronounced in the locule tissue, which was more sensitive to internal bruising than the other tissues. Changes observed in the volatile profiles appear to be related to disruption of cellular structures.

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Mildred N. Makani, Steven A. Sargent, Lincoln Zotarelli, Donald J. Huber, and Charles A. Sims

Early-maturing potato cultivars (Solanum tuberosum L.) grown in many subtropical and tropical regions are typically packed and shipped without curing. The objective of this study was to evaluate two early-maturing potato cultivars (‘Fabula’ and ‘Red LaSoda’) grown under four nitrogen fertilizer (NF) rates and harvested at three intervals after vine kill for effects on tuber physical and compositional quality at harvest and during storage. NF was applied through fertigation (0, 112, 224, or 336 kg·ha−1) and compared with granular NF application (224 kg·ha−1). The tubers were harvested weekly after vine kill (H1, H2, and H3) then evaluated for quality at 7 and 14 days during storage at 10 °C/80% to 85% relative humidity (RH). ‘Fabula’ tubers from H1 had the highest cumulative weight loss (3.6%) after 14 days of storage (season 1), while those from both H1 and H2 were highest (4.4%) in season 2, regardless of NF application method or rate. Tuber firmness increased by 1.5 newtons (N) for tubers from H1 after 7 days storage, and again by 0.76 N after 14 days for tubers from H2 and H3. Periderm dry matter content (DMC) for H1 tubers increased to 13.9% after 7 days, regardless of fertilizer treatment, in contrast to those from H2 or H3 where DMC remained constant throughout storage (10.6% and 11.4%, respectively). For ‘Red LaSoda’, cumulative weight loss in season 1 for H1 tubers was 2.2% after 14 days storage, whereas that for H2 and H3 tubers averaged 0.7%; this trend was similar for season 2. Periderm DMC significantly increased with increased storage time; that for H2 tubers was highest (19.6%) after 14 days. In both cultivars, tuber ascorbic acid content (AAC), soluble solids content (SSC), and total titratable acidity (TTA) remained constant throughout the 14-day storage period. Periderm maturity of ‘Fabula’ and ‘Red LaSoda’ potatoes had a greater effect on tuber physical and compositional quality during storage than the fertilizer rates or application methods. Fertigation at NF rates of 112, 224 or 336 kg·ha−1 was comparable with conventional granular NF application for growing high-quality tubers with acceptable postharvest life. Growing tubers at 112 kg·ha−1 nitrogen via fertigation has the potential to reduce both irrigation water usage and fertilizer runoff during the production cycle.

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Nicole L. Shaw, George J. Hochmuth, Steven A. Sargent, and Ed A. Hanlon

`Camelot' bell pepper was grown in a N fertigation study on sandy soil using polyethylene-mulched and fumigated beds. Portions of N (0%, 33%, 67%, 100% of total season N) were applied at bed formation. The remaining N was injected weekly into the drip irrigation system. Total N application treatments were 64, 128, 192, and 256 kg·ha–1. Early and total-season marketable fruit yields increased linearly with N rate. Preplant fertilizer proportion did not influence early yields, but late and total-season marketable fruit yields decreased linearly as preplant fertilizer proportion increased. Petiole sap NO3-N concentration increased with increasing N rates, but decreased linearly as preplant fertilizer proportion increased. Petiole sap NO3-N concentrations fell below critical levels for all N rates and preplant fertilizer proportions early in the season. Whole-leaf N concentrations were higher than critical values (>40 g·kg–1) throughout the season. Preplant fertilizer proportion had a significant linear effect on whole-leaf N concentrations for all sampling periods. Petiole sap was better correlated to yield data than whole-leaf N.

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Jiwon Jeong, Jeffrey K. Brecht, Donald J. Huber, and Steven A. Sargent

A study was conducted to determine the influence of the ethylene action inhibitor, 1-methylcyclopropene (1-MCP), on the shelf life and deterioration during storage at 5 °C of intact netted muskmelon (Cucumis melo L. var. reticulatus) fruit and fresh-cut cubes prepared from those fruit. ‘Durango’, ‘Magellan’, and ‘7920’ fruit (3/4 to full-slip stage) were treated with 1-MCP (1.0 μL·L−1) for 24 h at 20 °C. Preliminary research with ‘Athena’ muskmelon had shown that the more physiologically advanced distal pericarp tissue developed significantly more watersoaking than the less advanced proximal and center portions during 5 °C storage; therefore, after treatment with 1-MCP and cooling to 5 °C, the center portions of the fruit were used to prepare the fresh-cut samples. Fresh-cut cubes and intact fruit were stored for 12 d at 5 °C. Intact fruit of all tested cultivars responded to 1-MCP application with improved firmness retention during storage, but no watersoaking was observed in intact fruit. The effect of 1-MCP treatment on the firmness retention and watersoaking of fresh-cut cubes from the different cultivars was inconsistent. Exposure of muskmelon fruit to 1-MCP did not significantly influence the flesh color or soluble solid contents of either intact fruit or fresh-cut cubes during storage at 5 °C.

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Jiwon Jeong, Jeffrey K. Brecht, Donald J. Huber, and Steven A. Sargent

A study was conducted to determine the effect of 1-methylcyclopropene (1-MCP) on textural changes in fresh-cut tomato (Lycopersicon esculentum, Mill.) slices during storage at 5 °C. The relationship between fruit developmental stage and tissue watersoaking development was also determined. Fresh-cut tomato slices prepared from light-red fruit that had been exposed to 1-MCP (1 μL·L-1 for 24 h at 5 °C) retained significantly higher pericarp firmness during storage at 5 °C for 10 d than slices from nontreated fruit or slices stored at 10 or 15 °C and they also had a significantly higher ethylene production maximum. 1-MCP (1 or 10 μL·L-1 for 24 h at 5 °C) had no affect on the firmness of fresh-cut, red tomato slices at 5 °C or on slices prepared from 5 °C-stored, intact red tomatoes. Nor did 1-MCP treatment have a significant effect on electrolyte leakage of tomato slices or intact fruit stored at 5 °C. Slices from fruit of the same developmental stage but with higher initial firmness values had less watersoaking development and responded better to 1-MCP treatment during 8 d storage at 5 °C. 1-MCP (1 μL·L-1) was more effective in reducing watersoaking in light red stage tomato slices when applied at 5 °C for 24 h compared with 1-MCP applied at 10 or 15 °C. Watersoaking development was also more rapid in fresh-cut tomato slices as initial fruit ripeness advanced from breaker to red stage. Our results suggest that watersoaking development in fresh-cut tomato slices is an ethylene-mediated symptom of senescence and not a symptom of chilling injury as had previously been proposed.

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Luther C. Carson, Monica Ozores-Hampton, Kelly T. Morgan, and Steven A. Sargent

Florida best management practices include the use of controlled-release fertilizers (CRFs), which are soluble nutrients coated with a resin, polymer, sulfur, or a polymer covering a sulfur-coated urea. The purpose of this study was to compare the effects of three CRFs (coated, homogenized NH4NO3 and urea, and coated KNO3) rates in a hybrid CRF/soluble nitrogen fertilizer (SNF) system and two SNF rates [University of Florida/Institute of Food and Agricultural Science (UF/IFAS) and grower standard] on seepage-irrigated fall tomato (Solanum lycopersicum L.) yields, leaf-tissue nitrogen (LTN) concentration, postseason soil nitrogen (N) content, and postharvest fruit quality. Treatments of 112, 168, and 224 kg·ha−1 CRF N plus 56 kg·ha−1 SNF for total N of 168 (CRF112/SNF56), 224, and 280 kg·ha−1 were compared with IFAS (224 kg·ha−1) and grower standard (280 kg·ha−1) of pre-plant SNF. Tomatoes were planted on 29 Aug. 2011 and 3 Sept. 2012 on polyethylene mulch. Air temperature averaged 23.0 and 22.6 °C for the 2011 and 2012 fall seasons with 33.4 and 37.4 cm of rainfall, respectively. Soil temperatures ranged from 15.2 to 40.1 °C in 2011 and 13.6 to 36.6 °C in 2012. Leaf tissue N concentration exceeded the UF/IFAS-recommended sufficiency range for all treatments and sample dates, except CRF112/SNF56 at the last sample date of 2012. There were no differences in extra-large and total marketable yield at first harvest nor in total extra-large yield (three harvests combined) among treatments in 2011; however, total marketable yield for UF/IFAS, CRF112/SNF56, 168/SNF56, and 224/SNF56 was greater than that of the grower standard. In 2012, CRF112/SNF56 and CRF168/SNF56 had the greatest first harvest extra-large and total yield, but there were no differences between season total marketable yields. No differences between treatments were found for total N remaining in the soil postseason in 2011 or 2012. The grower standard, UF/IFAS, and CRF112/SNF56 were firmer at red ripe (less fruit deformation) in 2011, but there were no differences in 2012. In 2011, CRF112/SNF56 and CRF224/SNF56 were rated highest in red color among the treatments, and in 2012 there were no differences. A hybrid system containing lower and equal N rates (112 to 168 kg·ha−1 CRF N and 56 kg·ha−1 SNF56) compared with UF/IFAS-recommended rates produced comparable marketable yield and fruit quality.