Diascia ×hybrida (diascia) is a cool season vegetative annual produced in 6 weeks in an 11.4-cm pot under greenhouse production. Early experiments noted that during simulated shipping in a growth chamber at 26.7 ± 0.3 °C, 0 μmol·m-2·s-1 PPF and 50% RH, diascia flowers abscised. To test the effect of 1-MCP on retention of flowers during shipping, three hundred diascia plants were grown under temperature set points of 24°/18 °C day/night in a glass greenhouse. Three harvests of 42 plants each were made as plants became marketable i.e., open flowers on six racemes. The treatments were factorial with three shipping durations (0, 1, or 2 days) and two 1-MCP (1-Methylcyclopropene, Ethylboc, Floralife, Waterboro, S.C.) treatments (0 mg·L-1 and the commercially recommended application rate) and seven plants per treatment. Plants were boxed and sealed under 4-mL clear plastic tarps with duct tape and then treated with 1-MCP gas or water for 4 hours before moving to the growth room (19 °C, 10 μmol·m-2·s-1 PPF) for 2 weeks. They remained in the boxes for the duration of simulated shipping treatments. Flower number, racemes with open flowers and a quality rating were given when removed from the shipping boxes. For plants in the first and second harvests, 1-MCP significantly reduced flower and raceme abscission 1 week after shipping regardless of shipping duration; this was not seen in the third harvest. Two weeks post shipment there was no difference in flower numbers between 1-MCP treated and untreated plants. With two exceptions, no differences among measured variables occurred due to shipping duration.
Shannon E. Beach* and Terri W. Starman
Justin Butcher, T.E. Morelock, and D.R. Williams
Fresh-shelled southernpeas [Vignaunguiculata(L.) Walp.] is a popular vegetable. Postharvest storage of fresh-shelled peas is a crucial step in the production process. Farmers strive to produce a product that is high in quality and freshness with appropriate texture and appealing color. Improper storage and handling of southernpeas will result in deterioration. In an effort to prevent potential losses of southernpeas, this study was conducted to determine the best method to ship and store shelled peas. Five southernpea varieties: `Early Acre', `Early Scarlet', `Excel Select', `Coronet', and `Arkansas Blackeye #1' were planted in a randomized block design at the University of Arkansas. Twelve mature green pods of each variety were subjected to a sweated and unsweated treatment and then shelled. After shelling, seed were subjected to four different environmental conditions, and each treatment was evaluated for changes in physical appearance. Objectives of the study were to determine the best variety and environmental condition to maintain a quality marketable product. The study showed that a refrigerated environment at or near 3 to 5 °C allowed the crop to be stored for up to 2 weeks. It also appeared that sweating assisted with the shelling process and maintained appearance of each variety longer.
Ji Gang Kim, Yaguang Luo, Robert A. Saftner, and Kenneth C. Gross
Fresh-cut tissues are subjected to severe injury during preparation that leads to increased respiratory activity and quality deterioration. Modified atmosphere packaging (MAP) has been used to maintain quality of fresh-cut produce, but O2 depletion and excessive CO2 accumulation can be injurious. This study was conducted to evaluate the effect of delayed packaging and MAP using two different oxygen transmission rate (OTR) films on quality maintenance and shelf stability of fresh-cut romaine lettuce (Lactuca sativa L.). Romaine lettuce leaves were cut, washed, dried, and placed for 0, 4, 8, and 12 hours at 5 °C in ambient air before packaging. Fresh-cut samples were placed into packages prepared from films having OTRs of 8.0 and 16.6 pmol·s-1·m-2·Pa-1, flushed with N2 to reach an initial headspace O2 level of 1.5 kPa O2, and stored at 5 °C for up to 14 days. Delayed packaging affected gas composition, fermentative volatile production, off-odor development, color, CO2 injury, and tissue electrolyte leakage. With increasing delay before packaging, fermentative volatile production, off-odor development, and CO2 injury progressively decreased and discoloration increased. The modified atmospheres obtained with 16.6 OTR film increased discoloration when present, and generally had less off-odor development and CO2 injury compared to MAP with 8.0 OTR film. Delayed packaging affected overall quality of fresh-cut romaine lettuce packaged with both films. A 12-hour delayed packaging into packages prepared from 8.0 OTR film maintained quality by inhibiting CO2 injury, off-odor development, and tissue electrolyte leakage. However, an 8-hour delayed packaging into packages prepared from 16.6 OTR film was better at maintaining the quality of fresh-cut romaine lettuce at 5 °C for 14 days. The results indicated that delayed packaging could be an alternative method to optimize or balance package O2 during suboptimal OTR film packaging conditions.
Allyson M. Blodgett, David J. Beattie, and John W. White
Impatiens wallerana `Accent Red' were grown in a peat : perlite : vermiculite (PPV) or bark : peat : perlite (BPP) medium amended with SuperSorb-C (SS) or Soil Moist (SM) hydrophilic polymer and/or AquaGro-G (AG) wetting agent. In PPV or BPP, neither SS nor SM significantly increased shoot dry weight. In PPV, quality ratings were higher for plants grown in nonamended or SS- or SM- amended medium than for plants in AG-amended medium. In BPP, quality ratings were highest for plants grown in nonamended, AG-, or SM + AG-treated medium. Number of days from final irrigation to permanent wilting point (PWP) was greater in AG, SS + AG, or SM + AG treatments in PPV than in control, SS, or SM treatments, due to smaller plants in AG-amended media. In both media, root dry weight was not significantly greater with the use of either hydrophilic polymer or wetting agent. However, in PPV, AG suppressed root growth compared to the control.
Barbara L. Goulart, Philip E. Hammer, Kathleen B. Evensen, Wojciech Janisiewicz, and Fumiomi Takeda
The effects of preharvest applications of pyrrolnitrin (a biologically derived fungicide) on postharvest longevity of `Bristol' black raspberry (Rubus occidentals L.) and `Heritage' red raspberry [R. idaeus L. var. strigosus (Michx.) Maxim] were evaluated at two storage temperatures. Preharvest fungicide treatments were 200 mg pyrrolnitrin/liter, a standard fungicide treatment (captan + benomyl or iprodione) or a distilled water control applied 1 day before first harvest. Black raspberries were stored at 18 or 0 ± lC in air or 20% CO2. Red raspberries were stored at the same temperatures in air only. Pyrrolnitrin-treated berries often had less gray mold (Botrytis cinerea Pers. ex Fr.) in storage than the control but more than berries treated with the standard fungicides. Storage in a modified atmosphere of 20% CO2 greatly improved postharvest quality of black raspberries at both storage temperatures by reducing gray mold development. The combination of standard fungicide or pyrrolnitrin, high CO2, and low temperature resulted in more than 2 weeks of storage with less than 5% disease on black raspberries; however, discoloration limited marketability after≈ 8 days under these conditions. Chemical names used: 3-chloro-4-(2'-nitro-3'-chlorophenyl) -pyrrole (pyrrolnitrin); N-trichloromethylthio-4-cyclohexene-l12-dicarboximide (captan); methyl 1-(butylcarbamoyl) -2-benzimidazolecarbamate) (benomyl); 3-(3,5 -dichlorophenyl) -N-(l-methylethyl -2,4-dioxo-l-imi-dazolidinecarboxamide (Rovral, iprodione).
Shahrokh Khanizadeh, Martine Deschênes, Audrey Levasseur, Odile Carisse, Rong Cao, Raymond Yang, Jennifer DeEll, J. Alan Sullivan, and Jean-Pierre Privé
`Clé des Champs' is a new June-bearing strawberry cultivar (Fragaria ×ananassa Duch.) bred for Eastern Central Canada and climates similar to Quebec conditions. `Clé des Champs' was released for pick-your-own and shipping because it has very attractive light red, glossy (Fig. 1), and firm fruit, which have an excellent shelf life compared with `Kent'.
Luiz Lima, Brandon Hurr*, and Donald Huber
Ethylene induces postharvest problems in many fruits, including members of the Cucurbitaceae. The effects of ethylene and its antagonist 1-methylcyclopropene (1-MCP) were studied on cucumber fruit, a cucurbit harvested immature. Beit Alpha cucumbers (cv. Manar) were harvested and exposed to 0.5 or 1.0 μL·L-1 1-MCP prior to exposure to ethylene at 10 μL·L-1 at 15 °C. Fruit exposed to ethylene exhibited significant quality loss upon exposure to ethylene, including epidermal yellowing, a 40% reduction in firmness and, following longer exposure (6 d), epidermal sloughing and placental watersoaking. After 8 d, cucumbers exhibited a 75% reduction in firmness and acute pathogen incidence. Control fruit (no ethylene, no 1-MCP) were visually acceptable but firmness had declined 30% compared with initial values. Fruit exposed to 1-MCP were resistant to applied ethylene, with firmness declining 10 (1.0 μL·L-1 1-MCP) to 20% (0.5 μL·L-1) during storage for 14 d at 15 °C. Firmness of fruit treated with 1-MCP at 1.0 μL·L-1 was 28% higher than controls receiving only air, suggesting that ethylene production contributes to softening of cucumber during storage. The softening and watersoaking of fruit treated with ethylene was accompanied by downshifts in pectin mol mass. Fruit exposed to 1-MCP showed significantly reduced mol mass downshifts. The data indicate that cucumber show a PCD response to ethylene that is largely prevented by suppression of ethylene perception. The response of cucumber to ethylene parallels that for other cucurbits, and provides additional information that the benefits of 1-MCP extend beyond application to climacteric fruits.
F. Chéour, C. Willemot, J. Arul, J. Makhlouf, and Y. Desjardins
The objective of this study was to compare the effects of the foliar application of CaCl2 on the shelf life and Ca content of the fruit of the strawberry (Fragaria × ananassa) cultivars Kent and Glooscap, which differ in fruit firmness. Calcium was applied repeatedly, 3 days, 3 and 6 days, or 3, 6, and 9 days before harvest at 0, 10, or 20 kg·ha-1. Calcium treatment influenced amounts of free sugars and organic acids, color, texture, and disease development during storage in air at 4C. Calcium application had more effect on the fruit of the softer `Glooscap', which contained relatively low levels of Ca at the time of treatment. Calcium content of the fruit appeared to depend mainly on the ability of the plant to accumulate and distribute Ca.
Solomon I. Shibairo, Mahesh K. Upadhyaya, and Peter M.A. Toivonen
Replacing postharvest moisture loss in carrots (Daucus carota L., `Caro-choice') by single and repeated recharging (rehydration in water) treatments, interaction between the duration of recharging and temperature during recharging, and the effects of these treatments on moisture loss during subsequent short-term storage were studied. Carrot mass gain increased with increase in duration of single recharging treatments. Carrots that had lost 2.96% of their mass during storage at 13 °C and 35% relative humidity regained as much as 83% of the mass during recharging for 12 hours. Longer rechargings had little additional effect. Recharging at 13 °C and 26 °C was more effective at replacing water than at 0 °C. The rate of moisture loss (percent per day) during subsequent storage was not affected by recharging duration and temperature during recharging. With repeated recharging every 3.5 days, increase in recharging duration up to 9 hours increased carrot mass gain. Most of the mass gain occurred following 0 to 7 days of storage. These treatments, however, did not affect the rate of moisture loss during subsequent storage. These results suggest that the beneficial effect of recharging on carrot quality is due to replacement of the lost moisture and not to a decrease in moisture loss during storage following recharging. Abrading increased mass loss in non-recharged carrots and increased mass gain during recharging. Recharging should be explored as an option to improve the shelf life of carrots.
James D. Hansen, Harvey T. Chan Jr., Arnold H. Hara, and Victoria L. Tenbrink
Phytotoxicity from hydrogen cyanide (HCN) fumigation was measured in several varieties of Hawaiian cut flowers and foliage (Zingiberaceae, Heliconia, Orchidaceae, Marantaceae, Lycopodiaceae, Agavaceae, Proteaceae) as a potential disinfestation treatment. Concentrations tested were 2500, 3700, 4600, and 5500 ppm HCN for 30 min. All foliage and most heliconia were undamaged at fumigation levels of 5500 ppm HCN; most protea and `Midori' anthuriums were uninjured at 4600 pm HCN; red and pink ginger were uninjured at 3700 ppm HCN; and all pincushion protea showed phytotoxicity to HCN. Red ginger was quickly damaged when exposed to sunlight immediately after treatment at 2500 ppm HCN. No injury was observed in simulated shipment tests of red ginger and `Ozaki' anthuriums fumigated at 2500 ppm HCN. Wet, red ginger flowers longer than 6 cm were damaged at 2500 ppm HCN, whereas shorter flowers were uninjured. Wet `Ozaki' anthuriums showed phytotoxicity only at 4600 ppm HCN. Wet, treated lycopodium and bamboo orchid foliage was not injured. The number of marketable days and shelf life of the treated plant material were estimated from the visual ratings.