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C. Gupton, J. Clark, D. Creech, A. Powell, and S. Rooks

Rabbiteye (Vaccinium ashei Reade) and southern highbush (mostly V. corymbosum L.) type blueberry selections were evaluated in regional trials at five locations. Entry × location interactions (E × L) were significant for all traits in the rabbiteye type and all except plant productivity, plant volume, Julian date of 50% ripe fruit, and berry weight at harvest 3 in the southern highbush type. Despite the significant interactions, selection FL80-11 and `Gulfcoast' were the earliest flowering rabbiteye and southern highbush entry, respectively, at each location. Significant E × L for plant volume and yield suggests that adaptation to the local environment is important in the selection of potential cultivars. Fruit quality traits appear less affected by environment than fruit production traits for the entries tested.

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Joseph C. Goffreda

The stony hard gene in peach is a recessive gene which increases fruit firmness and shelf-life. Five progenies segregating for the stony hard trait were scored for several ripening-related characteristics. Fruit from stony hard segregants produced little or no ethylene, had lower respiration rates, and tended to ripen later than `normal' fruit. Stony hard fruit also had a lower percentage red overcolor in three of the five progenies. Stony hard fruit, harvested when firm-ripe, maintained their firmness after five days storage at 20°C. Firmness of stony hard fruit decreased significantly if the fruit were sprayed with ethephon (2-chloroethylphosphonic acid) at 250 ppm prior to storage. Fruit firmness of `normal' freestone or clingstone varieties was not significantly affected by the application of ethephon. The conversion of ethylene precursors to ethylene in stony hard fruit will also be discussed.

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J.P. Mattheis, J.K. Fellman, P.M. Chen, and M.E Patterson

Synthesis of non-ethylene volatiles (NEV) undergoes significant alterations during the transition from vegetative growth to senescence in apple fruit. This change results in a substantial increase in the production of esters characteristic of ripe apples. The relationship between changes in NEV synthesis and other indicators of physiological and horticultural maturity were investigated using `Bisbee Delicious' apples. Analysis of NEV was conducted using headspace sampling and GC-MS. Aldehydes and alcohols were the largest NEV components from pre-climacteric fruit although several esters were detected. The concentration of all NEV components declined to a minimum prior to the onset of the climacteric rise in ethylene synthesis. Initial detection of 2-methyl butylacetate, the major ester in ripening `Bisbee Delicious' fruit, occurred several weeks prior to the onset of the climacteric. The increase in ester synthesis accelerated during the post-climacteric period and the amount of total aldehydes also increased.

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Kenneth A. Shackel, H. Ahmadi, C. Greve, and J. Labavitch

The pressure microprobe was used to measure cell turgor (ψp) in tomato pericarp tissue, and also to sample vacuolar fluid for the measurement of cell osmotic potential (ψs) in a nanoleter freezing point osmometer. In fresh tissue, cell ψs agreed well with the ψs of frozen-thawed whole tissue measured with a vapor pressure osmometer. Under a wide range of ripeness conditions however, and for both intact fruit and discs of fruit tissue, fruit cell turgor was consistently lower than expected, based on the values of cell ψs. When tissue discs were hydrated in aerated distilled water, disc fresh weight increased substantially (20 - 50+%), and both cell turgor and tissue ψs increased. Cell ψs however, remained relatively constant. These and other observations suggest that the turgor increase during hydration was largely due to losses of solute from the apoplastic space, partly by direct losses from the tissue, and partly by cell solute accumulation.

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Ahmad Shirazi and Arthur C. Cameron

The feasibility of controlling relative humidity in modified atmosphere packages using compounds possessing Type III sorption isotherm behavior was studied. Ten grams each of dry sorbitol, xylitol, NaCl, KCl, or CaCl2 sealed with one maturegreen tomato (Lycopersicon esculentum L.) fruit at 20C in simulated packages for 48 days resulted in stable relative humidities of ≈75%, 80%, 75%, 85%, and 35%, respectively. Relative humidity was a function of the ratio of chemical to fruit mass. Relative humidities within control packages were in the range of 96% to 100% throughout the experiments. A simple system that uses spunbonded polyethylene pouches for the application of this humidity control method to packages is described. The storage life of packaged red-ripe tomato fruit at 20C was extended from 5 days using no pouch to 15 to 17 days with a pouch containing NaCl, mainly by retardation of surface mold development.

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John R. Stommnel

Fruit of the cultivated tomato, Lycopersicon esculentum, accumulate the reducing sugars glucose and fructose as the primary storage carbohydrates. In contrast, fruit of several wild green-fruited species store high concentrations of sucrose. Analysis of invertase, sucrose synthase (SS) and sucrose phosphate synthase (SPS) enzyme activity throughout fruit development in the sucrose accumulating species L. peruvianum, indicated low levels of invertase and SS during the period of significant sucrose accumulation. Increased SPS activity was noted during the sucrose accumulation phase but was not coincident with maximum rates of sucrose accumulation. The percent soluble solids in ripe L. peruvianum fruit was more than twice that present in L. esculentum and attributed primarily to the high level of sucrose accumulated in L. peruvianum. Analysis of fruit sugar content in F1, F2 and backcross populations derived from an initial cross between plants of sucrose and hexose accumulators suggests that recessive gene(s) are responsible for sucrose accumulation.

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Wayne T. Iwaoka, Xiaorong Zhang, Richard A. Hamilton, C.L. Chia, and C.S. Tang

The volatile compounds in soursop (Annona muricata L.) were obtained by a liquid-liquid continuous extraction procedure from the aqueous solution of blended soursop pulp and analyzed by gas chromatography (GC) and GC-mass spectrometry (MS). Twelve volatiles were identified by comparing their mass spectra and Kovats retention indexes with those of standard compounds: five were identified tentatively from MS data only, eight are being reported for the first time. (Z) -3-hexen-l-ol was the main volatile present in mature-green fruit, while methyl (E) -2-hexenoate, methyl (E) -2-butenoate, methyl butanoate, and methyl hexanoate were the four main volatiles present in ripe fruit. Concentrations of these five volatiles decreased and several other unidentified volatiles appeared when the fruit became overripe.

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David Sugar and Sally R. Basile

`Comice' pears (Pyrus communis) harvested early in the maturity range needed 25-31 days of storage at 0 °C to develop the capacity to ripen to an average firmness of 5 lbf within 5 days after being moved to 20 °C. After 24 h exposure to 100 ppm ethylene at 20 °C applied immediately after harvest, 17-27 days additional chilling were needed to develop ripening capacity, while ethylene exposure for 48 hours required an additional 7-17 days chilling. After 72 h ethylene exposure, ripeness was achieved within 5 days following 3 days cold storage, the minimum duration tested. Similar results were obtained when the sequence of ethylene treatment followed by cold storage was reversed. This technique may be applied to reduce the amount of time that `Comice' pears must be stored after harvest before marketing fruit with the capacity to ripen.

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J. Børve, E. Skaar, L. Sekse, M. Meland, and E. Vangdal

Three different rain protective covering methods for sweet cherry (Prunus avium) trees were tested with uncovered trees as control. The covers were a pitched cover mounted permanently, a similar cover mounted only when raining, and a permanent umbrella type enveloping the top and sides of single trees. Covers were mounted 3 weeks before and throughout the harvest period in two seasons with different weather conditions. All three covering methods increased the amount of marketable fruit from 54% on uncovered to 89% on covered trees in mean of 2 years. Fruit from umbrella covered trees had lower soluble solid content, lower juice color and lower ripeness compared with fruit from all other trees, reflecting the different microclimate in these trees such as frequently higher maximum temperatures and greater vapor pressure. The two pitched covers produced no significant changes in microclimate or internal fruit quality compared with uncovered trees.

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Lajos Helyes, Zoltán Pék, and Andrea Lugasi

Soluble solids (Brixo), carbohydrate, organic acid, lycopene, polyphenols and HMF content of indeterminate round type tomato Lemance F1 fruits were measured in six ripeness stages from mature green to deep red stage. Color of fruits was determined by CIELab system. The L*, a*, b* values were received directly and used to calculate from which the a*/b* ratio was calculated. The Brixo, carbohydrate, lycopene and HMF content were the highest in the deep red stage. Carbohydrate contents constitute nearly 50% of the Brixo. The mature green stage had the lowest acid content but in subsequent stages it was fundamentally unchanged. Polyphenol content changed little during fruit ripening. Lycopene content changed significantly during maturation and accumulated mainly in the deep red stage. Analyses showed that a*/b* was closely correlated with lycopene and can be used to characterize stages of maturity in fresh tomatoes.