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  • Author or Editor: Charles A. Sims x
  • HortTechnology x
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Grafting has many purposes in vegetable production. It is used for control of soilborne pathogens, season extension in protected culture, and improving productivity in cucurbitaceous and solanaceous crops. Consumers desire heirloom tomatoes (Solanum lycopersicum) for their perceived excellent flavor. Heirloom tomatoes are susceptible to many soilborne diseases and may benefit from grafting onto more robust, disease-resistant rootstocks especially under organic production. In this two-year study, heirloom tomato ‘Brandywine’ was grafted onto tomato hybrid ‘Survivor’ and interspecific tomato hybrid ‘Multifort’ rootstocks to determine the effects of grafting on fruit quality attributes such as soluble solids content (SSC), pH, total titratable acidity (TTA), and vitamin C. Nongrafted and self-grafted ‘Brandywine’ tomatoes were included as controls. Consumer sensory tests were also conducted to assess the effects of grafting on overall appearance and acceptability, firmness, tomato flavor, and sweetness. No significant differences in vitamin C, SSC, pH, or TTA were found in fruit from the nongrafted, self-grafted, and ‘Brandywine’ grafted with the two rootstocks either year. The SSC of all tomatoes in 2010 was lower than that of 2011. In 2010, fruit from ‘Brandywine’ grafted onto the rootstock ‘Survivor’ was scored significantly lower in appearance, acceptability, and flavor than the nongrafted ‘Brandywine’ treatment. All grafted treatments resulted in a significant decrease in acceptability ratings in the consumer sensory test. No significant differences were observed between nongrafted and grafted treatments in 2011. Consumers who reported more frequent consumption of fresh tomato tended to give lower ratings for most sensory attributes evaluated. Harvest time and fruit ripeness need to be considered in future research to better understand the influence of grafting with selected rootstocks on fruit composition and sensory attributes of heirloom tomatoes.

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The ethylene inhibitor 1-methylcyclopropene (1-MCP) delays ripening of avocado (Persea americana) and many other fruits, but there are few reports of the influence of this ethylene inhibitor on sensory attributes. The objective of this study was to evaluate the effects of aqueous 1-MCP on fruit ripening and sensory attributes of ‘Beta’ avocado, a Guatemalan-West Indian hybrid. Treatment with aqueous 1-MCP at 2.77 μmol·L−1 (150 μg·L−1) for 1 minute effectively delayed ripening by 6 days, delaying the onset of climacteric and lowering respiration rates as compared with control. Treated fruit had greener peel and firmer pulp when ripe, and untrained sensory panelists could not detect differences in texture, flavor, and overall liking between treated and untreated fruit. Immersion of ‘Beta’ avocado in aqueous 1-MCP extended the shelf life to 14 days at 20 °C and 84% relative humidity, an increase of 6 days (75%) as compared with untreated fruit, without compromising sensory acceptability. This technology has the potential to permit shipment of these fruit to more distant markets than currently possible.

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The postharvest life of lettuce (Lactuca sativa) is variable and negatively affected by mechanical injury, incomplete cooling, and poor genetic quality. Lettuce breeders are developing cultivars with a longer shelf life and rely on subjective, destructive, and time-consuming methods for quality analysis. One method of accelerating quality evaluations is known as accelerated shelf-life testing (ASLT), which has the potential to assist breeders in assessing lettuce quality and shelf life. The objective of this research was to determine the quality traits that significantly affect shelf life to develop an ASLT procedure to rapidly assess the postharvest quality of lettuce accessions in breeding programs. In Test 1, Romaine lettuce quality was evaluated using one subjective and five objective parameters during storage at 5, 10, 15, or 20 °C. Results determined that weight loss, lightness*, and hue* angle were best correlated with the overall appearance rating, whereas storage at 10 or 15 °C differentiated the shelf-life potential quickly and without excessive deterioration. In Test 2, these objective characteristics and storage temperatures were used to study rates of quality deterioration of a commercial Romaine cultivar (Okeechobee) and a breeding line (60182), both with long shelf lives, and a Batavia lettuce cultivar (La Brillante) with a short shelf life. Lettuce was evaluated during storage at 10 °C (winter and spring seasons) or at 15 °C (winter season). Weight loss was the most appropriate quality index for lettuce at these storage temperatures for a single harvest, whereas lightness* and hue* angle were the most appropriate indices for comparing quality between harvests. To apply ASLT to postharvest assessments of lettuce, breeders and other researchers should include two controls with good and poor shelf life (similar to ‘Okeechobee’ and ‘La Brillante’, respectively) as standard baseline cultivars during storage at either 10 or 15 °C.

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This study investigated the effect of ethylene treatment at high temperatures of 30 to 40 °C for up to 72 hours on subsequent ripening-associated processes in mature green ‘Sunny’ and ‘Agriset 761’ tomatoes (Solanum lycopersicum). Compared with ethylene-treated fruit at 20 °C, ethylene exposure at 30 or 35 °C stimulated ripening in terms of ethylene biosynthesis and color development, but the ethylene effect was only apparent after transfer to air at 20 °C. There were no negative effects on ripe tomato quality related to ethylene exposure at 30 or 35 °C. However, ethylene production of tomatoes was permanently impaired by ethylene exposure at 40 °C for 48 or 72 hours even after transferring fruit to air at 20 °C; these fruit exhibited slow softening and color development. Our results suggest that tomatoes perceive ethylene at 30 to 35 °C despite impairment of ripening at those temperatures, with the accelerated ripening response becoming apparent only after transferring the tomatoes to air at lower temperature.

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The efficacy of several proprietary plastic pallet cover systems to maintain strawberry (Fragaria ×ananassa) fruit quality during commercial shipment was determined. ‘Albion’ fruit were harvested from farms near Watsonville, CA. Fruit in vented plastic clamshells were palletized and forced-air cooled to 33–35 °F. Different cover systems (CO2 West, PEAKfresh, PrimePro, Tectrol) were placed over the pallets. Pads that released carbon dioxide (CO2) gas were placed inside the CO2 West cover. The Tectrol cover was sealed to the pallet base, a partial vacuum was applied, and pressurized CO2 gas was injected inside. The systems other than Tectrol remained open at the base. Six separate shipments of palletized fruit were transported in refrigerated (32–39 °F) truck trailers to distribution centers in either Florida or Georgia in 2.3–4.7 days. CO2 concentrations within pallets at the beginning and end of transport were highest (11% to 16%) in the sealed Tectrol system and relatively low (0.06% to 0.30%) in the open CO2 West, PEAKfresh, and PrimePro cover systems. Relative to noncovered control fruit, which lost 0.8% fresh weight during shipment, the pallet covers reduced the transport-related weight loss by 38% to 52%. The incidence of fruit decay was low (1.0% to 1.4%) after transport but increased substantially following a 2-day shelf life at 68 °F. However, fruit from the Tectrol pallets exhibited significantly less decay (36%) after shelf life than the CO2 West (39%), noncovered control (41%), PrimePro (42%), and PEAKfresh (43%) pallets. Fruit sensory quality was unaffected by the different pallet cover systems. Our findings show that transporting strawberries in the sealed Tectrol pallet cover system, in which CO2 concentrations were elevated to 11% to 16%, was most effective in complementing current low temperature management practices to maintain fruit quality.

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