Abstract
Continuous ethylene treatment (100 ppm) of avocado fruit stored at 6°C, for 13 days, caused acceleration in respiration rate for the duration of the treatment. At the end of the low temperature treatment and, also, after transfer of the fruit to 20°C, polygalacturonase activity and softening of the fruit were enhanced by ethylene treatment in comparisons with non-treated fruit. Endogenous ethylene production of ethylene-treated fruit was suppressed markedly after transfer to 20°C. Fruit treated 24 hours with ethylene at 6°C at the beginning of the storage period, ripened similarly to untreated control fruits.
For avocado we suggest that in cold storage (6°C) the presence of ethylene should be avoided so that the shelf-life period of the fruit will not be reduced.
Ornamental gingers are popular cut flowers and have been promoted as a promising potted flower crop because of unique foliage, long-lasting colorful bracts, and few pest problems. Rhizomes are the primary means of propagation in late spring followed by shoot growth and flowering, and plants enter dormancy under short days in the fall. Termination of dormancy is important for greenhouse forcing and extending the growing season. Dormancy of storage organs can be terminated prematurely by temperature. Rhizomes of three ginger species (Curcuma alismatifolia Gagnep., C. cordata L., and Globba winittii C.H. Wright) were stored for 0,1, or 2 weeks at 10 or 15 °C followed by 0,1, or 2 weeks at 25, 30, or 35 °C to determine the effect on growth and flowering. Upon completion of treatment application, rhizomes were planted in a peat moss: bark: perlite mix and placed in a greenhouse with 25 °C day/21 °C night temperatures with 40% shade. Rhizome cold storage in combination with hot storage affected growth and development of ornamental gingers. Days to emergence (DTE) and days to flower (DTF) for Globba were hastened when rhizomes were stored for 3 weeks at 15 °C followed by 3 weeks at 30 °C. For C. alismatifolia, DTE and DTF were hastened when rhizomes were stored for 3 weeks at 10 °C followed by 3 weeks at 30 °C. For C. cordata, DTE and DTF were hastened with rhizome storage of 2 weeks at 10 °C followed by 3 weeks at 35 °C.
Freshly harvested `Fortune' mandarins (Citrus reticulata Blanco) were dipped for 3 minutes in 25 or 52C water and then stored for 5 weeks at 2C. Then, the fruit were or were not intermittently warmed at 10C for 3 days after each 4-day storage period. All fruit then were held at 20C for 1 week to simulate retail marketing. Chilling injury was more severe in fruit dipped in 25C water and stored at 2C than in fruit dipped in 25C water and stored under intermittent warming. The hot dip treatment significantly reduced the extent of damage during storage and the subsequent 1 week of holding at 20C. The hot dip treatment reduced the incidence of fungal decay, especially during holding at 20C. Dip temperature and storage conditions slightly affected fruit physiological and quality characteristics. We conclude that prestorage hot dip treatments can be used to improve `Fortune' mandarin storing qualities. Also, this practice may be combined with intermittent warming during cold storage, and it could help limit fungicide use in postharvest treatments.
Eight hundred and fifty-three clones of Russet Burbank and 1012 clones of Lemhi Russet were obtained from Native Plants, Inc. in 1988. The clones were produced via a tissue culture system designed to produce somoclonal variants. Four cycles of selection were completed from 1988-1991. Selection was based on resistance to blackspot bruise, a tuber flesh discoloration caused by condensation of free tyrosine; or the ability to produce light french fry color following cold storage. At the end of the four selection cycles all but six Russet Burbank clones and seven Lemhi Russet clones were eliminated. ANOVA across years was completed for the eleven somaclonal variants and Russet Burbank and Lemhi Russet checks.
Of the Russet Burbank clones, three were significantly (p = .05) more resistant to blackspot bruise and one had significantly better fry color after cold storage. All four clones had significantly reduced yield in comparison to the check clones. Of the Lemhi Russet clones, three were significantly more resistant to blackspot bruise, and four had significantly better fry color than the check clone. Only one of the seven clones (one with superior fry color designated L1908) did not show a significantly lower yield potential.
Abstract
High performance liquid chromatography of mature ‘Beurre d'Anjou’ and ‘Beurre Bosc’ pear (Pyrus communis L.) fruit flesh showed that the major phenolics at harvest were chlorogenic acid, catechin, and arbutin. Neither cultivar contained epicatechin nor p-coumaroyl quinate. During 160 days at –1°C the chlorogenic acid content of d'Anjou increased significantly. In ‘Bosc’, chlorogenic acid levels decreased during storage. Catechin content increased linearly while arbutin levels remained nearly constant in both cultivars. Coincident with the completion of the cold requirement for initiation of ripening and endogenous ethylene production, i.e., 20 days for ‘Bosc’ and 50 days for ‘d'Anjou’, there was an appearance of low levels of a p-coumaric acid derivative and trace amounts of epicatechin/p-coumaroyl quinate. At 120 days epicatechin/p-coumaroyl quinate increased in ‘d'Anjou’ but not in ‘Bosc’. There is a coincidence, and perhaps relationship, between ethylene production and the quantity as well as the composition of phenolics present during storage. Bruising pear fruit after 120 days of storage caused a 30% increase in chlorogenic acid and a 50% increase in catechin, but no increase in p-coumaric acid derivatives.
Abstract
Four-year-old ‘Marsh’ grapefruit (Citrus paradisi Macf.) trees on trifoliate orange [Poncirus trifoliate (L.) Raf.] were subjected to temperature regimes of 25° to 5°C over 11 weeks in controlled environment facilities. Levels of total fatty acids in the flavedo of tree fruit decreased over this period by ≈50%, regardless of temperature. After 5 weeks, the level of linoleic acid in the flavedo of grapefruit that had been kept at progressively cooler temperatures from 25° to 5° was 76% greater than the level in control fruit at 25°. On rewarming and cooling, the differential for linoleic acid in flavedo was 41%. Increases of linoleic acid in the flavedo of fruit on trees that were treated with lower temperatures occurred in six lipids, with the greatest increases in phosphatidyl choline and wax-sterol esters. Chilling injury in harvested fruit during cold storage occurred slightly earlier in fruit from trees exposed to low temperatures, but was most severe in nonacclimated fruit.
Abstract
Peel samples of ‘Marsh’ grapefruit (Citrus paradisi Macf.) from 2 separate chilling injury (CI) experiments conducted during the 1979–80 season were analyzed for proline. Proline levels were highest in the peel of grapefruit after the seasonal night temperatures reached their minimum and levels declined after night temperatures increased in the spring. The greatest resistance of grapefruit peel to CI during postharvest cold storage coincided with high proline concentrations. Peels of unexposed interior canopy fruit had higher proline contents and were also more resistant to CI than peels of exposed exterior canopy fruit. Proline accumulation may be a consequence of an environmental stress rather than a cause of hardening to the stress or a mechanism of resistance.
`Elegant Lady', `O'Henry' and `September Sun' peaches [(Prunus persica (L.) Batsch (Peach Group)] and `Summer Bright' and `Summer Grand' nectarines [(Prunus persica (L.) Batsch f. nucipersica (Nectarine Group)] heated to a seed surface temperature of 47.2 °C over a period of 4 hours developed mealy flesh sooner and to a much greater extent than nonheated fruit following cold storage at 5 °C for 1 to 3 weeks. Exo- and endopolygalacturonase activities were reduced following 3 to 4 hours of heating and may have been responsible for the increased mealiness. Mealiness often developed in defined regions rather than throughout the entire fruit. Comparison of juicy and mealy regions within individual fruit revealed that mealy regions contained 65% and 86% less exo- and endopolygalacturonase activity, respectively, than juicy regions, whereas pectinmethylesterase activity was unchanged. Extractable protein was reduced by >50% in the mealy regions of the fruit. Intermittent warming periods of 24 hours at 20 °C at weekly intervals during storage at 5 °C were less effective in reducing mealiness in heat-treated than in control fruit. It is important that future work with heat treatments and stone fruit closely monitor potential effects on this disorder to avoid loss of market quality following treatment.
Abstract
Control of woolly breakdown in ‘Elberta’ peaches was obtained by removal of the fruit to ambient room temperature (23–25°C) for 48 hours after 2 and 4 weeks' storage at 0°C. A 6 weeks' storage life was thus obtained. Warming the fruit after cold storage intervals shorter than 2 weeks was less effective after longer storage periods; the disorder was often enhanced by removal to room temperature.
A hypothesis to explain the development of woolly breakdown on the basis of these and previous data is discussed. It is suggested that further prolongation of storage could be obtained by repeated exposures to room temperature.
Greenhouse- and field-produced plants of Asclepias tuberosa L., butterfly flower, were forced in the greenhouse under various daylengths to produce flowering plants for the florist industry. Examined were post-production cold storage temperature (4.5 and 10C) and period (12, 14, and 16 weeks), forcing daylength (9, 13, 15, or 17 hours), plant-production scheme (greenhouse- vs. field-produced), and planting depth (exposed crowns or crowns planted 1.3 cm below the medium surface). When forced under a 9-hour daylength, blind shoots and aborted flower buds were prevalent. When daylengths exceeded 13 hours, using night interruption, the time to produce a marketable plant was reduced from 71 days to 61 days for 18-month-old greenhouse-produced plants. Daylength of 17 hours delayed flowering of field-produced liners by 15 days in comparison to those forced under 13-hour daylength. Greenhouse-produced plants stored at 10C did not sprout when brought into the forcing greenhouse held at 17/25C (night/day). Field-produced plants, when greenhouse-forced, had fewer flowers per inflorescence (88 to 94 flowers) than greenhouse-produced plants (79 to 87 flowers).