Abstract
Six cranberry (Vaccinium macrocarpon Ait.) cultivars, (water harvested under New Jersey growing conditions) were evaluated for their suitability for fresh market sale. Fruit were hand-picked and water-reel picked, held in the bog flood water for 0-, 4-, 8-, 12-, and 24-hr periods, and then stored for 12 weeks at 3°C. After an additional 4 days at 21° storage the fruit were evaluated for fungal fruit rot and physiological breakdown (PB). ‘Franklin’, ‘Pilgrim’, and ‘Stevens’ were superior to ‘Early Black’ and ‘Wilcox’ as measured by occurrence of rot and PB. Water immersion time had a greater influence on PB than on rot. As time in the water increased, the percentage of fruit manifesting PB increased, with ‘Ben Lear’ developing the least and ‘Early Black’ and ‘Wilcox’ the most PB.
Abstract
Tubers of Begonia × tuberhybrida Voss cvs. Ruffled Pink and Roseform Salmon, stored for 8 weeks at 2.5°C, respired more rapidly during a subsequent 24 hr at 20° to 21° than did tubers stored at 5° or 7.5°. Exposure of tubers to 1 μ·liter1 ethylene during a 48-hr period prior to planting had no effect on sex expression or other quality parameters of the plants at flowering. Storage of tubers in a 2-3% O2 atmosphere for up to 20 weeks at 5° increased the percentage of tubers sprouted compared to those stored in air. No differences in sex expression, flower size or doubleness, days to flower, or plant height at flowering were observed between low-O2 and air storage at any duration.
Abstract
Incorporation of thiabendazole (TBZ) in the wax coating applied to grapefruit significantly reduced the amount of low temp pitting which developed during prolonged storage at 8 and 12°C.
Abstract
Bell peppers (Capsicum annuum L.), individually wrapped in plastic film or nonwrapped, were held 7, 14, or 21 days at 1°, 4°, or 7°C plus an additional 5 days at 15° to evaluate the effect of film wrapping on chilling injury. Film wrapping did not reduce the incidence of visible chilling injury on either pericarp or seeds. Chilling injury was progressively more severe the lower the storage temperature.
Abstract
Ripening of ‘Bartlett’ pears at 20°C was assessed in samples harvested weekly beginning 4 weeks prior to commercial harvest maturity. Ripening was promoted by delaying harvest, by 1- and 2-week periods of storage at 4.4°C, or both. Early summer treatments with 750 and 7500 ppm succinic acid-2,2-dimethylhydrazide (SADH) delayed ripening but this effect was counteracted by both delayed harvest and postharvest storage at 4.4°C. It is concluded that SADH delays ripening by influencing an endogenous mechanism for controlling ripening in pears.
Ethanol concentration and chlorophyll fluorescence (CF) were measured as signs of heat stress in apple fruit [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.]. `McIntosh', `Cortland', `Jonagold', and `Northern Spy' apples were placed in trays and exposed to 46 °C for 0, 4, 8, or 12 hours. Following treatments, fruit were stored in air at 0 °C and evaluated after 0, 1, 2, or 3 months. Ethanol and ethylene production, CF, peel and flesh browning, firmness, skin color, soluble solids, and titratable acidity were measured. Increases in ethanol were apparent immediately following 12-hour heat treatments as well as after 3 months. After 3 months, ethanol concentrations were 16-, 52-, 6-, and 60-fold higher in `McIntosh', `Cortland', `Jonagold', and `Northern Spy' apples than in controls, respectively. The concentrations of ethanol accumulated reflected the degree of heat-induced fruit injury. Heat treatments reduced ethylene production relative to control values. After 3 months of storage ethylene production of fruit exposed to 46 °C for 12 h was <0.48 μmol·kg-1·h-1 compared to >4.3 μmol·kg-1·h-1 for controls. Heat treatments also reduced CF which was expressed as Fv/Fm, where Fv is the difference between the maximal and the minimal fluorescence (Fm - Fo), and Fm is the maximal fluorescence. After 3 months storage at 0 °C, Fv/Fm was ≈0.2 in fruit held at 46 °C for 12 hours compared with 0.5-0.6 for control fruit. Exposure to 46 °C for 12 hours caused severe peel and flesh browning in all cultivars. Severity of peel and flesh browning increased with increasing duration of heat treatment and subsequent storage at 0 °C. `Northern Spy' apple fruit were most susceptible to heat stress based on the degree of flesh browning. Heat treatments of 8 and 12 hours reduced firmness of `McIntosh', `Cortland', and `Northern Spy', but not `Jonagold' apples. Hue angle of the green side of fruit was also reduced in `Cortland', Jonagold' and `Northern Spy' apples receiving the 8- and 12-hour treatments. Heat treatments caused a decrease in fruit tiratable acidity, but had no effect on soluble solids content. The increase in ethanol production and decrease in CF correlated with heat-induced injury, and were apparent before browning was visually apparent. Ethanol and CF have the potential to be used to nondestructively predict the severity of injury that develops during storage.
`D'Anjou' pears (Pyrus communis, L.) growing in 3 locations with the elevation at 150 meters, 380 meters, and 610 meters respectively in Hood River valley, Oregon were harvested at the commercial maturity with the flesh firmness of 62.3 Newton (±2.2 N) and stored in air at -1°C. Regardless of different growing elevations, the incidence of superficial scald became noticeable after 2.5 months of storage and became substantial after 3 months. The rate of scald development was higher on the fruit from 150 meters elevation than those from higher elevations. Alpha-farnesene and conjugated trienes in the peel tissue accumulated at faster and higher rates in the fruit from 380 meters and 610 meters elevations than those from 150 meter elevation. The threshold level of conjugated trienes which causes superficial scald disorder was different from the fruit grown at different elevations.
Seeking non-chemical alternatives to use of DPA for scald control on apples, we interrupted storage with a brief warming period. This often reduces chilling injuries of fruit. Warming `Granny Smith apples for 5 days at 20 C after 2 weeks at 0 C reduced scald as effectively as a 1000 ppm DPA treatment at that time. To better characterize this response, we tested other timings of the warming period, and also lower warming temperature. Warming at 10 C, or for shorter times at 20 C, or after longer periods at 0 C all were less effective. Maintaining a warm period before storage was not effective. During warming of `Cortland' and `Delicious' apples softening and loss of green color occurred, the extent of which increased with warming time and usually was greater if the fruit had initiated the ethylene climacteric before warming.
Preclimacteric `Golden Delicious' apples (Malus domestica Borkh.) were stored at 0 °C in: air; air + 5% CO2; 2% O2 + 98% N2; or 2% O2 + 5% CO2 + 93% N2, and sampled monthly for 4 months to investigate the mechanism(s) by which reduced O2 and/or elevated CO2 atmospheres inhibit C2H4 biosynthesis. Ethylene biosynthesis rates and in vitro ACS activity were closely correlated in all treatments, while in vitro ACO activity significantly increased over time regardless of the treatment. Only a small amount of C2H4 biosynthesis inhibition by lowered O2 and/or elevated CO2 atmospheres could be accounted for by suppressed induction of ACO activity. Western blot analysis demonstrated that apples held for 2 months in lowered O2 and/or elevated CO2 atmospheres had significantly reduced abundance of ACO protein, compared to fruit held in air. Northern blot analysis of ACS and ACO transcript abundance revealed that reduced O2 and/or elevated CO2 atmospheres delay induction and reduce the abundance of both transcripts. Reduced O2 and/or elevated CO2 atmospheres reduce C2H4 biosynthesis by delaying and suppressing expression of ACS at the transcriptional level and by reducing the abundance of active ACO protein. Chemical names used: 1-aminocyclopropane-1-carboxylic acid (ACC), ACC synthase (ACS), ACC oxidase (ACO), ethylene (C2H4), S-adenosylmethionine (AdoMet).
Ozone treatment has many advantages for control of fungal diseases. There are no residue concerns, no registration is required, and it is non-specific, therefore potentially effective against a broad spectrum of pathogens. However, ozone is known to cause plant damage. There is little information available on either the ozone tolerance of floriculture crops or the levels required to kill plant pathogens under commercial conditions. Nine floriculture crops (begonia, petunia, Impatiens, Kalanchoe, pot roses, pot chrysanthemums, lilies, snapdragons and Alstroemeria) were subjected to increasing levels of ozone. Trials were conducted at 5 and 20 °C (90% to 95% RH) and ozone exposure was for 4 days for either 10 hours per day (simulating night treatment) or for 10 minutes every hour. Damage was assessed immediately after treatment and after an additional 3 days at room temperature in ozone-free air. Trials were terminated for the crop when an unacceptable level of damage was observed. Trials to determine the lethal dose for actively growing pathogens (Alternaria alternata, Alternaria zinniae and Botrytis cinerea) and fungal spores were conducted under identical conditions. Ozone tolerance varied with plant type and ranged between <0.2 and 3ppm. Generally, the crops surveyed were more susceptible to ozone damage at the low temperature. As a group, the bedding plants were the least tolerant. Fungal spores were killed at treatment levels between 0.8 and 2 ppm ozone. The actively growing fungal mycelium was still viable at 3 ppm ozone when the trial had to be terminated due to ozone-induced structural damage in the treatment chambers. Under the trial conditions, only the Kalanchoe would be able to tolerate the high levels of ozone required to kill the fungal spores.