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  • Author or Editor: Lorenzo Zacarias x
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Several citrus varieties, including `Navel' oranges, `Marsh' grapefruit and `Fallglo' tangerines are prone to develop postharvest peel pitting at nonchilling temperatures. The disorder is characterized by depressions in flavedo that ultimately affect oil glands. Increasing evidence indicates that changes in peel water status during postharvest handling of fruit plays a major role in the appearance of the disorder. Peel pitting was triggered when fruit were transferred from low to high relative humidity (RH) consistently in several citrus growing areas. A transient increase in fruit ethylene production and ABA content was observed within the first 24 hours after transfer from low to high RH. Water potential decreased with storage at low RH in flavedo and albedo, and recovered faster in flavedo than in albedo cells upon transfer to high RH. The differential recovery in water potential between flavedo and albedo is postulated to cause collapse of external albedo layers and pitting. The effect of climatic conditions in the field at harvest was also examined. Harvesting fruit at low RH induced more severe pitting after storage than harvesting at high RH. In addition, increasing hours of low RH storage prior to storage at high RH resulted in increased pitting. The results demonstrate that change in peel water status is a major factor leading to the development of postharvest peel pitting in citrus.

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Several citrus cultivars including `Marsh' grapefruit (Citrus paradisi Macf.) and `Fallglo' tangerine [Bower citrus hybrid (C. reticulata Blanco × C. reticulata × C. paradisi) × Temple tangor (C. reticulata × C. sinensis L. Osbeck)] are prone to develop postharvest peel pitting at nonchilling temperatures. This disorder is characterized by depressions in flavedo that ultimately affect oil glands. Although the fundamental cause for this disorder has not been well defined, increasing evidence indicates that alteration in peel water status during postharvest handling of fruit plays a major role. `Fallglo' tangerines developed postharvest peel pitting when transferred from low (30%) to high (90%) relative humidity (RH) storage. To determine the number of hours of dehydration prior to storage at high RH sufficient to induce peel pitting in `Marsh' grapefruit and `Fallglo' tangerines, fruit were exposed to low RH conditions for increasing periods of time and then washed, coated with commercial shellac-based wax, and stored at high RH. Only 2 hours of low RH storage were sufficient to induce peel pitting in `Fallglo' and `Marsh' after transfer to high RH. The severity of pitting in `Fallglo' tangerines was greater than in `Marsh' grapefruit. Weight loss of fruit at the end of low RH storage and peel pitting after 3 weeks of storage at high RH were significantly correlated. RH conditions in the field at the time of harvest affected susceptibility to peel pitting in both cultivars. Peel pitting was more severe when fruit were harvested at low field RH than high field RH when followed by treatments that induce peel pitting. The data suggest that harvesting susceptible cultivars at high RH, and minimizing exposure to low RH after harvest, could reduce the commercial impact of postharvest peel pitting.

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Continuous treatment with 8% ethanol doubled the vase life of `White Sim' carnation (Dianthus caryophyllus L.) flowers. Other alcohols, other concentrations of ethanol, or pulse treatments with up to 8% ethanol had little or no effect. Butanol and longer-chain alcohols shortened vase life and caused the flower stem to fold. During their eventual senescence, the petals of ethanol-treated flowers did not inroll; instead, individual petals dried slowly from their tips. Very little ethylene was produced by ethanol-treated flowers, and the normal increase in ACC content and EFE activity was also suppressed. Ethanol treatment also decreased the flowers' sensitivity to exogenous ethylene.

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