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  • Author or Editor: H. Day x
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Respiration rate and bruising incidence were assessed in new cherry (Prunus avium L.) cultivars adapted to high temperatures. `Bing', `Brooks', `Tulare', and `King' respiration rates were evaluated at 0,5,10, and 20C, and bruising susceptibilities at 0, 10, 20, and 30C. `Bing' was the least susceptible to bruising and had the lowest respiration rate at all temperatures. Respiration rate increased with temperature in all cultivars. Impact bruising damage was greatest in all cultivars when fruit flesh was below 10C. Vibration damage was not influenced by fruit temperature. Our results suggest that the cherry cultivars assessed should be handled at temperatures between 10 and 20C during packing to minimize bruising damage. Due to increased respiration rates at higher temperatures, however, fruit should be cooled to 0C within 4 to 6 hours after harvest.

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Skin discoloration (SD) formation in peach [Prunus persica (L.) Batsch] and nectarine [Prunus persica (L.) Batsch, var. nectarine] was related to physical damage (abrasion) to the fruit during fruit handling (harvest and hauling operations) within the orchard and during transport to the packinghouse. Vibration and rubbing treatments increased SD formation indicating that tissue damage is involved in SD formation. Anatomical studies comparing sound and SD-injured tissues done by scanning electron and light microscopy indicated that very-low-intensity physical damage could induce brown and/or black spots because of cell disruption in the epidermal and hypodermal layers. The fact that injury was specific to the exocarp tissues (cuticle, epidermis, and hypodermis), and that mesocarp tissue located below the exocarp cells remained sound and turgid, indicated that abrasion injury is associated with SD. Similar types of visible and anatomical injury characteristics were induced by a rubbing treatment, demonstrating that physical abrasion damage affecting just exocarp cells was enough to induce SD:

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The influence of modified atmosphere packaging (MAP) on quality attributes and shelf life performance of ‘Friar’ plums (Prunus salicina) was studied. Plums were stored at 0 °C and 85% relative humidity for a 60-day period in five different box liners (LifeSpan L316, FF-602, FF-504, 2.0% vented area perforated, and Hefty liner) and untreated (control). Flesh firmness, soluble solids concentration, titratable acidity, and pH were unaffected by the box liners. Fruit skin color changes were repressed on plums packed in box liners that modified gas levels and weight loss was reduced by the use of any of the box liners. Plums packed without box liners (bulk-packed) had ≈6% weight loss. High carbon dioxide (CO2) and low oxygen (O2) levels were measured in boxes with MAP box liners (LifeSpan L316, FF-602, and FF-504). Percentage of healthy fruit was unaffected by any of the treatments during the ripening period (shelf life) after 45 days of cold storage. However, after 60 days of cold storage, fruit from the MAP box liners with higher CO2 and lower O2 levels had a higher incidence of chilling injury (CI) symptoms, evident as flesh translucency, gel breakdown, and “off flavor” than fruit from the other treatments. Overall, results indicate that the use of MAP box liners is recommended to improve market life of ‘Friar’ plums up to 45 days cold storage. However, the use of box liners without gas control capability may lead to CI symptoms in fruit cold-stored for longer periods.

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Brown discoloration of the core, carpels, and flesh areas of `Ya Li' and `Seuri' Chinese pears [Pyrus bretschmeideri (Rehd.)] depended on harvest date. Fruit harvested no later than 180 days after full bloom (3000 degree days) did not develop the disorder. Browning of the core and flesh tissues increased when cooling was delayed, but was not influenced by subsequent storage temperatures of 0,10, or 20C. In both cultivars, the onset of internal browning was evident after storage in fruit that had been harvested when skin color had changed from green to light green-yellow. Thus, skin color can be used to determine harvest date to avoid internal browninincidence during storage of `Ya Li' and `Seuri' Chinese pears.

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Peach and nectarine skin discoloration or inking (SD) has become a fruit industry problem in the last decade. Spots on the skin may be black, tan, purple or brown and vary in shape. SD was related with physical abuse of the fruit occurring during handling (harvest and transport operations) within the orchard.

An anatomical study comparing healthy and damaged (black and brown) tissue of different peach and nectarine varieties was done with the Scanning Electron Microscope (SEM) and Light Microscope (LM). This study indicated that only exocarp cell (epiderm and cuticle) damage was associated with SD. The internal compartmentation of the damaged cells was often disrupted with the contents of the cytoplasm and vacuole mixed and expelled. Mesocarp cells were always intact and turgid. The same anatomical and visible tissue injury symptoms were induced on fruit by abrasion treatments.

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Abstract

‘Cortland’ and ‘Delicious’ apples were treated with 2 concn of butylated hydroxytoluene (BHT) and 3 levels of diphenylamine (DPA) at 3 temp levels over a 2-year period. On ‘Cortland’ apples, BHT at 10,000 ppm reduced scald as effectively as 2,000 or 4,000 ppm DPA. BHT also reduced scald on ‘Delicious’. BHT residue analyses indicated that most of the BHT remained in the peel of the apple, but the residue was greatly reduced in cold storage within 72 hr after treatment.

Open Access

A commercial controlled delayed cooling or preconditioning treatment was developed to extend peach (Prunus persica) market life of the most popular California peach cultivars. A 24 to 48 h cooling delay at 68 °F (20.0 °C) was the most effective treatment for extending market life of internal breakdown susceptible peaches without causing fruit deterioration. This treatment increased minimum market life by up to 2 weeks in the cultivars tested. Weight loss and softening occurred during the controlled delayed cooling treatments, but did not reduce fruit quality. Detailed monitoring of these fruit quality changes during the delayed cooling period and proper use of fungicides is highly recommended for success in this new fruit delivery system. Rapid cooling after preconditioning is important to stop further fruit deterioration such as flesh softening, senescence, decay and weight loss. Controlled delayed cooling can also be used to pre-ripen susceptible and nonsusceptible peaches to deliver a ready-to-buy product to the consumer.

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Increasing environmental concerns and legislation in many states and in other countries require that we take a more comprehensive sustainable “best management” approach to production techniques in nursery and greenhouse operations. This is particularly important because these production facilities are typically intense users of resources that are applied to relatively small land areas. We have developed an online knowledge center to facilitate the implementation of more sustainable practices within the nursery and greenhouse industry. A web-based knowledge center provides the most cost-effective mechanism for information delivery, as our potential audiences are extremely diverse and widespread. We currently have a registered user database of over 450 educators, growers, and industry professionals, and undergraduate and graduate students. A gateway website provides an overview of the issues and the goals of the project. The associated knowledge center currently has 25 in-depth learning modules, designed in a Moodle learning management framework. These learning modules are designed to actively engage learners in topics on substrate, irrigation, surface water, and nutrient and crop health management, which are integral to formulating farm-specific strategies for more sustainable water and nutrient management practices. Additional modules provide assessment and implementation tools for irrigation audits, irrigation methods and technologies, and water and nutrient management planning. The instructional design of the learning modules was paramount because there can be multiple strategies to improve site-specific production practices, which often require an integration of knowledge from engineering, plant science, and plant pathology disciplines. The assessment and review of current practices, and the decision to change a practice, are often not linear, nor simple. All modules were designed with this process in mind, and include numerous resources [pictures, diagrams, case studies, and assessment tools (e.g., spreadsheets and example calculations)] to enable the learner to fully understand all of the options available and to think critically about his/her decisions. Sixteen of the modules were used to teach an intensive 400-level “Principles of Water and Nutrient Management” course at the University of Maryland during Spring 2008 and 2009. The water and nutrient management planning module also supports the nursery and greenhouse Farmer Training Certification program in Maryland. The Maryland Department of Agriculture provides continuing education credits for all consultants and growers who register and complete any module in the knowledge center. Although these learning resources were developed by faculty in the eastern region of the United States, much of the information is applicable to more widespread audiences.

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