, and storage environment. Postharvest loss of cranberry fruit is primarily the result of physiological breakdown and decay ( Forney, 2003 ). Physiological breakdown is associated with overmature fruit ( Doughty et al., 1968 ), bruising ( Patterson et
Thomas H. Boyle, Fabian D. Menalled, and Maureen C. O'Leary
The existence of self-incompatibility (SI) was demonstrated in `Britton' and `Rose' Easter cactus (Rhipsalidopsis). In a full diallel cross among five clones, 18 out of 20 outcrosses resulted in 68% to 100% fruit set, whereas reciprocal crosses between two of the clones and all five self-pollinations failed to set fruit. Pollen tube growth was greatly inhibited in styles of selfed pistils, but there was no evidence of pollen tube inhibition in compatibly crossed pistils. Easter cactus exhibited characteristics typically found in sporophytic SI systems (trinucleate pollen, papillate stigmas, and scant stigmatic exudate) together with those associated with gametophytic SI systems (stylar inhibition of pollen tube growth and absence of reciprocal differences in outcrosses). Additional experiments were performed to determine the effects of bud pollinations, growth regulators (BA, GA3, and NAAm), and high temperatures (0- to 48-h exposure at 40C) on the SI response. Heat treatments were more effective than either bud pollinations or growth regulators in overcoming SI, and yielded an average of 7.2 viable seeds per treated flower when plants were incubated for 12 h at 40C and selfed immediately after incubation. Isozyme analysis of the S0 parent and putative S1 progeny confirmed that selfing had occurred following heat treatments. Using S1 progeny in breeding programs may extend the flower color range and lead to a greater diversity in other plant characteristics than presently exists in cultivated germplasm. Chemical names used: N-(phenylmethyl)-1H-purin-6-amine [benzyladenine (BA)], gibberellic acid (GA3), and α-naphthaleneacetamide (NAAm).
Judith A. Abbott, A. Raymond Miller, and T. Austin Campbell
Mechanical stress received by pickling cucumbers (Cucumis sativus L.) during harvest can cause physiological degeneration of the placental tissues, rendering the cucumbers unsuitable for use in some pickled products. Cucumbers were subjected to controlled stresses by dropping and rolling under weights to induce such degeneration. Following storage at various temperatures for O, 24, and 48 hours, refreshed delayed light emission from chlorophyll (RDLE) was measured and transmission electron micrographs of chloroplasts were made. Mechanical stress rapidly suppressed RDLE and induced accumulation of starch granules within the chloroplasts. Rolling usually had a greater effect on RDLE than did dropping. After 48 hours, RDLE suppression persisted; starch granules were no longer evident in chloroplasts from mechanically stressed fruit, but very electron-dense inclusions had developed in the chloroplasts. Storage temperatures affected RDLE levels but had minimal interaction with stress responses. Cucumber lots subjected to excessive mechanical stress likely could be detected using RDLE measurement.
Charles F. Forney
High-quality cranberry (Vaccinium macrocarpon) fruit are required to fulfil the growing markets for fresh fruit. Storage losses of fresh cranberries are primarily the result of decay and physiological breakdown. Maximizing quality and storage life of fresh cranberries starts in the field with good cultural practices. Proper fertility, pest management, pruning, and sanitation all contribute to the quality and longevity of the fruit. Mechanical damage in the form of bruising must be minimized during harvesting and postharvest handling, including storage, grading, and packaging. In addition, water-harvested fruit should be removed promptly from the bog water. Following harvest, fruit should be cooled quickly to an optimum storage temperature of between 2 and 5 °C (35.6 and 41.0 °F). The development of improved handling, refined storage conditions, and new postharvest treatments hold promise to extend the storage life of fresh cranberries.
Adel A. Kader
Biological factors involved in deterioration of fresh horticultural perishables include respiration rate; ethylene production and action; compositional changes associated with color, texture, flavor (taste and aroma), and nutritional quality; growth and development; transpiration; physiological breakdown; physical damage; and pathological breakdown. There are many opportunities to modify these inherent factors and to develop genotypes that have lower respiration and ethylene production rates, less sensitivity to ethylene, slower softening rate, improved flavor quality, enhanced nutritional quality (vitamins, minerals, dietary fiber, and phytonutrients including carotenoids and polyphenols), reduced browning potential, decreased susceptibility to chilling injury, and increased resistance to postharvest decay-causing pathogens. In some cases the goals may be contradictory, such as lowering phenolic content and activities of phenylalanine ammonialyase and/or polyphenoloxidase to reduce browning potential vs. increasing polyphenols as antioxidants with positive effects on human health. Another example is reducing ethylene production vs. increasing flavor volatiles production in fruits. Overall, priority should be given to attaining and maintaining good flavor and nutritional quality to meet consumer demands. Extension of postharvest life should be based on flavor and texture rather than appearance only. Introducing resistance to physiological disorders and/or decay-causing pathogens will reduce the use of postharvest fungicides and other chemicals by the produce industry. Changes in surface structure of some commodities can help in reducing microbial contamination, which is a very important safety factor. It is not likely that biotechnology-based changes in fresh flowers, fruits, and vegetables will lessen the importance of careful and expedited handling, proper temperature and relative humidity maintenance, and effective sanitation procedures throughout the postharvest handling system.
Charles F. Forney, Stephanie Bishop, Michele Elliot, and Vivian Agar
Extending the storage life of fresh cranberries (Vaccinium macrocarpon Ait.) requires an optimum storage environment to minimize decay and physiological breakdown (PB). To assess the effects of relative humidity (RH) and temperature on storage life, cranberry fruit from four bogs were stored over calcium nitrate, sodium chloride, or potassium nitrate salts, which maintained RH at 75%, 88%, and 98%, respectively. Containers at each RH were held at 0, 3, 5, 7, or 10 °C and fruit quality was evaluated monthly for 6 months. Both decay and PB increased with increasing RH in storage. After 6 months, 32%, 38%, and 54% of fruit were decayed and 28%, 31%, and 36% developed PB when stored in 75%, 88%, and 98% RH, respectively. The effects of RH continued to be apparent after fruit were removed from storage, graded, and held for 7 days at 20 °C. The decay of graded fruit after 4 months of storage in 75%, 88%, or 98% RH was 10%, 13%, and 31%, respectively, while PB was 12%, 12%, and 17%, respectively. Fresh weight loss decreased as RH increased averaging 1.9%, 1.4%, and 0.7% per month for storage in 75%, 88%, and 98% RH, respectively. Fruit firmness was not affected by RH. Storage temperature had little effect on decay. However, PB was greatest in fruit stored at 10 °C, encompassing 55% of fruit after 5 months of storage. When graded fruit were held an additional 7 days at 20 °C, decay and PB were greater in fruit previously stored at 0 or 3 °C than at 5, 7, or 10 °C. Fresh weight loss increased as storage temperature increased, averaging 0.8%, 1.0%, 1.3%, 1.7%, and 1.9% per month at 0, 3, 5, 7, and 10 °C, respectively. Fruit firmness decreased during storage, but was not affected by storage temperature. To maximize storage and shelf life, cranberry fruit should be stored in a RH of about 75% at 5 °C.
Adriana Contreras-Oliva, Cristina Rojas-Argudo, and María B. Pérez-Gago
Postcosecha de Frutas y Hortalizas CYTED San Carlos, Cojedes, Venezuela 9 Miller, E.V. Heilman, A.S. 1952 Ascorbic acid and physiological breakdown in the fruits of the pineapple (Ananas comosus L. Merr.) Science 116
Mohsen Hatami, Siamak Kalantari, Forouzandeh Soltani, and John C. Beaulieu
at 5 °C. A similar pattern was also observed in late-harvested ‘Zangi-Abad’ and ‘Kermanshah’ fruit at 5 °C. Accelerated physiologic breakdown and increased incidence of pathologic decay occurs in chilling-sensitive melon fruit stored at a chilling
Emilie Proulx, Yavuz Yagiz, M. Cecilia, N. Nunes, and Jean-Pierre Emond
Chlorophylls content of persistent-green and normal snap bean pods (Paseolus-vulgaris L) J. Amer. Soc. Hort. Sci. 96 362 365 Miller, E.V. Heilman, A.S. 1952 Ascorbic acid and physiological breakdown in the fruits of the
Konstantinos G. Batziakas, Shehbaz Singh, Kanwal Ayub, Qing Kang, Jeffrey K. Brecht, Cary L. Rivard, and Eleni D. Pliakoni
physiological breakdown ( Prusky, 2011 ). However, maintaining the optimum storage temperature is not always feasible, especially in smaller horticultural operations ( Cantor and Strochlic, 2009 ; Harrison et al., 2013 ). The optimum postharvest temperature for