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James Gibson and Bradford C. Bearce

Poinsettia (Euphorbia pulcherrima Willd. Ex Klotsch) cultivars `Dynasty Red', Nutcracker Pink', and `Annette Hegg Topwhite' were planted in 15-cm azalea pots containing peat: vermiculite (1:1, v:v) in which coal bottom ash sieved through 6-mm mesh was mixed in proportions of 0%, 25%, or 50% by volume. Planting date was 23 July 1996, and pinch date was 25 Aug. Harvest date at anthesis was 16 Dec. Plant heights of all cultivars were increased in the ash media. L, a, and b, values measured with a Minolta CR-200 chroma meter differed very slightly among ash levels within cultivars. Mean per plant bract cluster count was very similar among ash levels and cultivars. Mean diameter of largest bract cluster was increased above that of 0% coal ash plants for `Topwhite' plants in 50% coal ash media. Mean per plant dry weights of all three cultivars were increased over those of control plants in both 25% and 50% coal ash media. Media pH increased with increase in ash, while EC tended to decrease. Media available Ca increased with ash increase, while Mg decreased and the same pattern was noted for leaf tissue Ca and Mg. This was probably due to release of Ca from the ash, which contains about 10% Ca oxides. Tissue levels of Ca and Mg were within acceptable ranges; however, K levels also declined in plant tissue to suboptimal levels with plants in ash media.

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Walter Boswell, Bernard Bible, and Suman Singha

Flesh color has been proposed as a maturity index for peaches. The objective of the present study was to determine the effectiveness of this parameter in `Loring', `Jersey Dawn', `Madison', and `Raritan Rose' peach (Prunus persica L. Batsch). Fruit were picked at weekly intervals at three or four harvest dates, with five fruit per cultivar being picked from each of three trees. Flesh firmness and soluble solids were measured immediately following harvest, and CIELAB coordinates (L*a*b*) of blush and flesh color were determined with a Minolta CR-200b calorimeter. There was a highly significant correlation (P < 0.001) between firmness and flesh hue angle for all four cultivars and with flesh chroma especially for the white-fleshed `Raritan Rose'. The correlation values between firmness and blush hue angle were consistently lower. Soluble solids did not consistently correlate with flesh or blush color. Even though blush color influences consumer preference, it was not as good an indicator of maturity as flesh color for the cultivars that we tested.

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Bernard B. Bible and Richard J. McAvoy

Forty-two poinsettia cultivars were grown as a 15-cm single-plant pinched crop at 21/16.5°C (day/night) temperatures during Fall 1995 with standard commercial practices for irrigating, fertilizing, and pest control. On 7 Dec., 156 consumers rated the cultivars for their overall appeal. On 11 Dec., color coordinate (CIELAB) readings for bracts and leaves were taken with a Minolta 200b colorimeter. The colorimeter was set to illuminate C and has a 8-mm aperture. Bracts and leaves were placed on a white tile background for colorimetric readings. In 1996, a similar evaluation was conducted with 55 poinsettia cultivars. Using the L-value of leaves as a criterion, cultivars were separated into medium green-leafed and dark green-leafed groupings. For bracts among the red types, hue angle values were used to separate cultivars into cool red types (hue angle ≈20–22°) and warm red types (hue angle ≈24–25°). Based on the 1995 study, cultivars within the cool red bracts and dark green foliage group—those that were darker, duller red (lower L and chroma)—were less attractive (lower consumer ratings) than lighter, more-vivid red cultivars. For cultivars within the cool red bracts and medium green foliage group, consumers preferred the darker duller red cultivars. Perhaps dark foliage gives a more pleasing contrast with the more vivid cool reds than does the medium green foliage. In general, consumers rated red cultivars hire than non-red cultivars.

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C. Jasso-Chaverria, G.J. Hochmuth, R.C. Hochmuth, and S.A. Sargent

Two greenhouse cucumber (Cucumis sativus) cultivars with differing fruit types [European (`Bologna') and Beit-alpha (`Sarig')] were grown during two seasons in a perlite medium in black plastic nursery containers in a passively ventilated greenhouse in northern Florida to evaluate fruiting responses to nitrogen (N) fertilization over the range of 75 to 375 mg·L–1. Fruit production, consisting mostly of fancy fruits, increased quadratically with N concentration in the nutrient solution, leveling off above 225 mg·L–1 for both cucumber cultivars. Fruit length and diameter were not affected by N concentration in the nutrient solution. Leaf N concentration, averaged over three sampling dates, increased linearly with N concentration in the nutrient solution from 46 g·kg–1 with 75 mg·L–1 N to 50 g·kg–1 with 375 mg·L–1 N. Fruit firmness decreased with increasing N concentration and there was little difference in firmness between the two cultivars. Firmness was similar across three measurement dates during the spring harvest season, but increased during the season in the fall. Fruit color responses to N concentration were dependent on the specific combination of experiment, sampling date, and cultivar. For most combinations of experiment, sampling date, and cultivar, cucumber epidermal color was greener (higher hue angle) with increased N concentration. The color was darkest (lowest L* value) and most intense (highest chroma value) with intermediate to higher N concentrations.

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Manuel Baez-Sañudo, Jorge Siller-Cepeda, Rosalba Contreras-Martinez, Laura Contreras-Angulo, Rosabel Velez, and Dolores Muy-Rangel

Mango `Keitt' is characterized by a poor external color development and a slightly high transpiration rate during ripening, which affect external quality. When fruit is ripening, the peel turns from a green to yellowish or dull green color, and the peel has no shine. We evaluated the effectiveness of three film coatings to reduce weight loss, improve appearance, and maintain quality during ripening of `Keitt' mango fruits. Four lots of fruits were obtained from a packinghouse in late September and transported to the laboratory. Each lot was sprayed at the commercial recommended rates with SemperFresh, Natural Shine, TFC 210, and FreshSeal coatings. Water sprayed fruits were used as a control. After applications, fruits were stored for 15 days at 22 °C and 85% RH to simulate marketing conditions. Quality parameters evaluated included weight loss (%), firmness, external and internal colors (hue, chroma, l), respiration rate (CO2 production), and chemical parameters such as pH, titratable acidity and °Brix. After 15 days, fruits coated with Natural Shine reduced 50% of the weight loss as compared to control fruits, while fruits coated with FreshSeal and SemperFresh reduced only 1.7% and 3.5%, respectively. Firmness declined from 155 N to 10 N during storage, being more evident on day 10, when fruits were table ripe. Fruits treated with SemperFresh were softer as compared with the other treatments. Titratable acidity decreased from 0.8% to 0.2% during storage and °Brix increased from 13 to 17–18 in all treatments. Fruit coated with Natural Shine had reduced weight and firmness loss. Additionally, fruits developed a better external color, with lower hue values, higher chromaticity and luminosity, which improve fruit appearance.

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Maria Claudia Dussi, David Sugar, and Ronald E. Wrolstad

The anthocyanin in `Sensation Red Bartlett' pear skin was characterized and quantified, and the effect of light quality on fruit color development was evaluated. Anthocyanin concentration was related to fruit chromaticity values. Pigments were analyzed using high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). One of two spots detected in the TLC chromatogram did not change color with molybdate sprays, indicating the possible presence of peonidin. HPLC analysis confirmed the presence of a major and a minor pigment, which co-eluted with cyanidin 3-galactoside and peonidin 3-galactoside. Monomeric anthocyanins in the pear skin extract were 6.83 mg/100 g of fruit peel. To study light quality, gelatin filters allowing passage of different wavelengths of-light were attached over the exposed side of `Sensation Red Bartlett' pears 1 month before harvest. Chromaticity was recorded before the filters were attached and after their removal at harvest using the Commission Internationale del'Eclairage (L*, a*, and b*) color space coordinates. Following color measurements, anthocyanin was extracted from individual skin disks. Skin beneath all filters yielded less hue than the control. Wavelengths that transmit above 600 nm had the largest effect on chroma, a*, and b* values. Fruit wrapped in aluminum foil to obscure all light had the highest luminosity. Wavelengths from 400 to 500 nm gave darker, less chromatic, and redder pear fruit. All treatments yielded higher anthocyanin content than the control. There was a tendency toward increased anthocyanin content with longer wavelengths. The simple linear regression of the log anthocyanin content on L* value and (a*/b*) provided an R 2 = 0.41.

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F. Maul and S.A. Sargent

The effects of prolonged ethylene exposure on external and internal quality parameters of tomato fruits were studied in order to explore the feasibility of its use as a nondestructive technique for screening immature and inferior quality fruit. `Agriset' and `CPT-5' tomatoes were hand harvested at Stage 1 (green) and held at 20°C and 50 ppm ethylene for 1-7 days. Each 24 hours, fruits reaching Stage 2 (breaker) were removed from C2H4 and transferred to 20°C air for subsequent ripening. Tomatoes were considered at edible maturity upon reaching full red-ripe stage and 4 mm deformation and final quality parameters were determined. For both cultivars, fruits which required prolonged C2H4 exposure to reach Stage 2 had lower overall visual appearance. `Agriset' tomatoes which required short exposure times to C2H4 (1 to 3 days) had somewhat higher quality than those requiring prolonged times (4 or 5 days). Days to reach edible maturity were 9.5 and 7.7, respectively. For the short exposure times, peel color was more intense (higher chroma value), while soluble solids content and total sugars were significantly higher (P = 0.05). Quality of `CPT-5' tomatoes was not adversely affected until requiring 6 or 7 days exposure to C2H4. Days to reach edible maturity decreased from an average of 12.5 to 11.0 for 1 to 5 or for 6 to 7 days exposure, respectively. For fruits requiring 7 days exposure, soluble solids content, total sugars and pH were significantly higher than for those reaching Stage 2 in fewer days. There were no significant differences in titratable acidity or ascorbic acid content for either cultivar.

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Mustafa Ozgen, Artemio Z. Tulio Jr., Ann M. Chanon, Nithya Janakiraman, R. Neil Reese, A. Raymond Miller, and Joseph C. Scheerens

To investigate phytonutrient accumulation in black raspberries, fruits of `Jewel' and `MacBlack' were harvested at stages from the onset of color development (S1) to ripe fruit (S7). S1–S7 samples were characterized for color reflectance and then frozen at –28 °C within an hour of harvest. Additional ripe fruit were maintained at 20 °C for 3 days to overripen (S8) before freezing. After storage, samples were analyzed for dry weight (DW), total soluble solids (TSS), fructose (FRU), glucose (GLU), and organic acid (ORG) contents; total phenolic (PHE) and anthocyanin (ACY) contents; individual cyanidin glycoside levels (ICG); and antioxidant capacity (FRAP and ABTS) by standard methodology. `Jewel' and `MacBlack' ripened similarly. Chroma values and DW percentage decreased while TSS levels, sugar contents (FRU+GLU), PHE, ACY, the ACY: PHE ratio, and ICG increased with progressive ripening stages (S1–S7). Values of PHE, ACY, and ICG were highly correlated (r < +0.95) with FRAP and ABTS values. ACY levels in S6 fruit were 18% to 23% less than those of S7; lower S6 ACY levels were associated with reduced antioxidant capacity in `MacBlack', but not `Jewel'. Overripened fruit (S8) exhibited increased DW (11% to 25%) and decreased sugar contents (16% to 17%), consistent with moisture and respiratory losses after harvest. After correction for these losses, S7 and S8 levels of PHE, ACY, FRAP, and ABTS were similar in `MacBlack'. However, as `Jewel' overripened, ACY levels and antioxidant activity increased 44% and 22% to 26%, respectively. Our data suggests that significant changes in the antioxidant behavior of black raspberries can occur during the periods surrounding peak ripeness.

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Adirek Rugkong, Jocelyn K.C. Rose, and Chris B. Watkins

Tomato fruit (Solanum lycopersicum L.) can develop mealiness and enhanced softening when exposed to chilling temperatures during storage, but the involvement of cell wall-associated enzymes in chilling injury development is not well understood. To study this aspect of injury development, we have exposed breaker-stage `Trust' tomato fruit to a chilling temperature of 3 °C for 0, 7, 14, and 21 days followed by storage at 20 °C for 12 days. Ethylene production was not affected by storage except after 21 days where production was greater at 20 °C. Exposure of fruit to chilling temperatures delayed the ripening-related color change (chroma and hue) and initially increased compression values, but percent extractable juice was not affected consistently. Increased polygalacturonase (PG) activity during ripening was reduced by about 50% after 7 days at 3 °C, and further inhibited with increasing storage periods. In contrast, the activities of pectin methylesterase (PME) and α-galactosidase were not significantly affected by the cold treatments. β-Galactosidase activity was greater in all chilled fruit compared with fruit ripened at harvest, whereas endo-β-1,4-glucanase activity was lower after 21 days at 3 °C. In chilled fruits, transcript accumulations for PG, PME (PME1.9), and expansin (Expt.1) were lower during storage at 20 °C compared with those of nonchilled fruits. Transcript accumulation for β-galactosidase (TBG4) was affected only at 14 days of cold storage, when transcript accumulation decreased. Cold treatment increased transcript accumulation of endo-β-1,4-glucanase (Cel1) after 12 days at 20 °C and decreased transcript accumulation after 7 days and 21 days at 21 °C. Cell wall analyses to investigate relationships among enzyme activities and cell wall disassembly are ongoing.

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Arturo Martinez-Morales, Iran Alia-Tejacal, Maria-Teresa Colinas-Leon, Victor Lopez-Martinez, and Cecilio Bautista

Sapote mamey (Pouteria sapota) fruit commercialization to different markets is limited due to the fact that it is a host of the fruit fly (A. serpentina), so there is a special interest in generating a quarantine treatment protocol. In the present study, fruits from Jalpa de Mendez, Tabasco, Mexico, were harvested at physiological maturity and divided in two groups: a) fruits treated with hot water (46.1 °C) for 1 h, and b) control fruits, with no hot water treatment. Fruits were then stored at 12 °C for 7, 14, 21, and 28 days. After storage, days to ripening as well as respiration rate, ethylene production, and weight loss were evaluated for 6 days. Pulp color (ligthness, hue angle, and chroma), fruit firmness, total soluble solids and sugars, and total phenols (at the end of storage and 6 days after) were also evaluated. Results show that fruits stored for 0 days ripened in 5.8 days, while fruits stored between 7 and 28 days took between 3.2 and 5.6 days to reach the ripe stage. Considering the storage periods, effective postharvest life was increased between 11 and 32 days. Respiration rate markedly increased in control fruits after 21 days of storage, but no chilling injury symptoms were observed. Hot water treatment did not affect ethylene production, sugar or phenol content, color, and fruit firmness. Total soluble solids and sugars increased as storage period increased and even more after storage, thus suggesting that storage temperature does not stop the ripening process. No significant changes were observed in the color components. Results suggest that the hot water inmersion treatment is an alternative to reach the quarantine protocol (not affecting quality) and when combined with refrigeration could be used to sent fruit to distant places.