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  • Author or Editor: D.A. Buchanan x
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Apple fruit storage lie is prolonged by low-oxygen cold storage, however, ethanol accumulates when oxygen concentration is reduced below the Pasteur point, Upon return to aerobic conditions, dissipation of ethanol occurs due to physical (evaporation) and biochemical processes. Oxidation of ethanol by apple fruit occurs at a slow rate, but ethanol also serves es a substrate for fruit volatile synthesis. This study was conducted to determine changes in concentrations of ethanol and other non-ethylene apple fruit volatiles following periods of anaerobiosis. `Delicious' apples were obtained from a commercial warehouse and stored at 0.05% O2, 0.2% CO2 and 1 C. One day following return to ambient oxygen conditions, several volatiles were identified from anaerobic fruit that were nor produced by the control fruit. All were eaters that contained an ethyl group as the alcohol-derived portion, These included ethyl acetate, ethyl butyrate, ethyl 2-methyl butyrate, ethyl hexanoate and ethyl octanoate. Several esters produced by the controls were not detectable from anaerobic fruit including butyl butyrate, butyl 2-methyl butyrate, propyl hexanoate and 3-methyl butyl hexanoate. After 7 days ripening at 20 C, the amount of ethanol and the additional ethylesters was reduced in anaerobic fruit. Synthesis of esters produced by control fruit but nor by anaerobic fruit during the initial volatile sampling had resumed after 7 days.

Free access

Abstract

Strategies for reducing bacterially induced frost damage to tender plants were examined. Introduction of the competitive bacterium, Erwinia herbicola M232A (not active in ice nucleation) did not lower the temperature at which freeze injury of tomato shoots occurred. Streptomycin was effective in reducing freeze damage of tomato shoots only when mixed with the Pseudomonas syringae suspension prior to plant inoculation. Spectinomycin, another aminoglycoside, was effective in reducing frost damage to tomato plants due to P. syringae. Bacteria present intercellularly (within the plant) may play a significant role in bacterial ice nucleation.

Open Access

Abstract

Sprays of (2-chloroethyl)phosphonic acid (ethephon) at 2000 ppm during petal fall resulted in satisfactory fruit thinning of peach (Prunus persica L.) but only moderate thinning when applied at the 80% bloom stage. Later applications also reduced crop loads but significantly increased the number of split pits.

Open Access

Fruit quality and volatile compounds produced by apple fruit (Malus ×domestica Borkh. `Gala') were characterized following regular atmosphere (RA) or controlled atmosphere (CA) storage at 1°C. Static CA conditions were 1, 1.9, 2.8, or 3.7 kPa O2. Fruit stored under dynamic CA conditions were exposed to ambient air 1, 2, or 3 days per week for 8 hours then returned to 1 kPa O2. All CA treatments included 2 kPa CO2. Ethylene production was reduced following CA storage plus 1 day at 20°C compared with apples stored in RA. Apples stored in static 1 kPa O2 and the dynamic treatments had lower ethylene production compared with apples stored in 1.9 to 3.7 kPa O2 after 90 and 120 days. Ethylene production by apples from all CA treatments recovered during a 7-day poststorage ripening period at 20°C. Ester production was reduced following CA at 1 kPa O2 after 60 days compared with RA-stored fruit. Production of butyl acetate by apples stored in 1 kPa O2 static CA was 29%, 30%, and 7% of that produced by RA-stored fruit after 60, 90, and 120 days storage plus 7 days at 20°C. Amounts of 2-methylbutyl acetate were not affected by CA storage, however, production of other 2-methylbutyrate esters was reduced following 1 kPa O2 storage. Ester production increased with O2 concentration after 90 days in storage. The dynamic treatments resulted in greater ester emission after 120 days storage plus 7 days at 20°C compared with apples stored in static 1 kPa O2. Production of 1-methoxy-(2-propenyl) benzene by apples subjected to dynamic treatments was also higher after 120 days storage plus 7 days at 20°C compared with apples stored in RA or static CA. No differences in firmness, titratable acidity or soluble solids content were observed between apples stored in 1 kPa O2 and the dynamic treatments. Firmness and titratable acidity were maintained better by dynamic treatments compared with static atmospheres containing > 1 kPa O2.

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Abstract

Photosynthesis in rabbiteye blueberry (Vaccinium ashei Reade) was found to saturate at low irradiances and had a low light compensation level. In contrast to many other plants, both stomatal and residual diffusion resistance contributed equally to the total leaf diffusion to CO2. Relatively higher stomatal resistances in rabbiteye blueberry result in an efficient water-use, enabling it to withstand drought. No cultivar differences were found in photosynthesis, transpiration, or dark respiration to account for differences in yield.

Open Access

Abstract

‘Tifblue’ rabbiteye blueberry (Vaccinium ashei Reade) yields were greatest when expressed as kg of fruit per bush; however, ‘Woodard’ outyielded ‘Tifblue’ and ‘Bluegem’ per m3 of canopy volume. ‘Tifblue’ was subjected to the greatest daytime water stress due to its large canopy volume and limited feeder root density. Consequently, changes in feeder root density had a pronounced effect on yields in ‘Tifblue’. Yield was also affected to a lesser extent by feeder root density in ‘Bluegem’ but was independent of this factor in ‘Woodard’.

Open Access

Quantitative and qualitative changes in net production of volatile compounds by apples occurs during fruit development with a major transition to ester production occurring as fruit ripening begins. Ester production during fruit ripening is an ethylene-mediated response; however, differences in maturation patterns among apple cultivars led us to examine the relationship between ester production and onset of the ethylene climacteric in several commercial apple cultivars. Emission of volatile esters as a function of apple fruit development was evaluated for `Royal Gala', `Bisbee Delicious', `Granny Smith', and `Fuji' apple fruit during two harvest seasons. Apples were harvested weekly and analyses of harvest maturity were performed the day after harvest. Non-ethylene volatiles were collected from intact fruit using dynamic headspace sampling onto Tenax traps. Fruit from each harvest was stored at 1°C in air for 5 months (3 months for `Royal Gala') plus 7 days ripening at 20°C, then apples were evaluated for the development of disorders. The transition to ester production occurred after internal ethylene exceeded 0.1 μL for `Royal Gala', `Bisbee Delicious', and `Fuji'. Ester emission by `Granny Smith' apples remained low throughout the harvest period. Increased ester emission occurred after the optimum harvest date (as determined by the starch index and internal ethylene concentration) for controlled-atmosphere storage of `Bisbee Delicious' and prior to optimum maturity for `Royal Gala' and `Fuji'. A relationship between the potential for development of superficial scald and ester production at harvest was evident only for `Bisbee Delicious' apples.

Free access

Enclosing apple fruit in bags during development is widely practiced in Japan. Bags create a barrier that reduces damage from insects and fungal pathogens as well as treatments to control these problems. Bags also reduce the incidence of sunburn and change fruit appearance by altering peel pigmentation composition, two features that have prompted northwestern United States producers to bag `Fuji' apples. Fruit maturity and quality of bagged and nonbagged Fuji apples grown in Washington state were evaluated at harvest and after refrigerated storage in air or controlled atmosphere. Bagged fruit had less watercore and lower ethylene production at harvest compared to non-bagged fruit with similar starch ratings. Bagged fruit had lower soluble solids content, titratable acidity and firmness at harvest and during storage. Emission of ester and alcohol volatiles was consistently lower for bagged fruit. Postharvest volatile emissions were negatively correlated with bagging duration during development. Bagged fruit had no incidence of a peel disorder with similarity to delayed sunscald.

Free access

Volatile esters from acids and alcohols are important components of flavor and odor perception in apples (Malus domestica Borkh.). We are interested in understanding the biochemical basis for ester synthesis/flavor retention in `Gala' apples held in controlled atmosphere storage. The relationship between acetyl CoA alcohol transferase (AAT) acetate ester-formin activity, non-ethylene volatile emission, and flesh volatile content of `Gala' apples during the maturation period and after removal from CA storage was investigated. At the appropriate times, apples were sampled for volatile compounds in the headspace and flesh using solid sorbent along with purge-and-trap capillary gas chromatography. Subsequently, acetate ester forming activity was assayed on partially-purified extracts of cortical tissue. During storage, the accumulation of the major flavor notes butyl acetate and 2-methyl butyl acetate in the flesh was decreased as oxygen levels in storage atmospheres were lowered. AAT activity is closely linked to the onset of climacteric ripening and is sensitive to atmospheres having low oxygen contents.

Free access

Abstract

Sprays of various concentrations of Fruitone, a commercial formulation containing 2-(3-chlorophenoxy)-propionamide and 2-(3-chlorophenoxy)-propionic acid (3CPA) or of 2-chloroethylphosphonic acid (Ethrel) were applied to ‘Early Amber’, a short cycle (70 days), low-chilling (300 hours < 45 F) peach grown in Florida. Adequate thinning of fruits was obtained from treatments during the 4-day interval that the endosperm was changing from the free nuclear to the completely cellular stage. The most satisfactory concn of 3CPA and Ethrel for fruit thinning were 300 and 30 ppm, respectively. All concn of 3CPA and Ethrel which caused fruit thinning also increased ethylene concn in the fruit.

Open Access