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Kareen Stanich, Margaret Cliff, and Cheryl Hampson

., 1980 ); although some exceptions exist ( Clarke, 1990 ; Judd et al., 1989 ), they appear to be tolerated statistically ( Zhang and Robson, 2002 ). Although fruit weight distributions are frequently reported in the literature, fruit firmness

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Peter M.A. Toivonen, Frank Kappel, Sabina Stan, Darrell-Lee McKenzie, and Rod Hocking

A convenient and reliable method that used a specially designed tool to apply a uniform bruising force in situ was developed to assess the relative susceptibility to fruit surface pitting in sweet cherry. Assessment of pitting with a visual scale after 2 weeks of 1 °C storage was found to be in close agreement with measurements of pit diameter. Using this method `Bing' showed the greatest susceptibility to pitting in both years of the study and `Bing', `Lapins', and `Sweetheart' cherries showed a decline in susceptibility as fruit matured. The predictive value of fruit firmness at harvest, fruit respiration at harvest, and weight loss in storage was assessed in relation to the severity of pitting. The model to best describe pitting was found to include all three physiological variables (firmness, respiration, and weight loss). While an acceptable model was obtained when combining all three cultivars, the best models were achieved when each cultivar was considered separately. It was concluded that there are likely unmeasured variables involved in determining susceptibility to pitting. Hence the best approach to predicting pitting susceptibility is the application of the pit-induction method described in this work.

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Donna A. Marshall, James M. Spiers, and Stephen J. Stringer

. Factors contributing to splitting in cherries include cultivar differences, water temperature, period of wetting, soluble solids, fruit firmness and turgor, and elasticity of the skin ( Ackley and Krueger, 1980 ; Bullock, 1952 ; Davenport et al., 1972a

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Ariana Torres, Susan S. Barton, and Bridget K. Behe

The United States environmental horticulture industry, or green industry, comprises wholesale nursery, greenhouse, and turfgrass sod producers; landscape design, installation and maintenance firms; as well as wholesale and retail distribution firms

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Troy A. Larsen* and Christopher S. Cramer

New Mexico onion production will begin using mechanical harvesters in the near future in order to stay competitive in today's market. Past onion breeding objectives have focused on improving onions for hand harvesting instead of mechanical harvesting. Our breeding program is starting to evaluate germplasm for bulb firmness. The objectives of this study were to evaluate hybrid lines for their bulb firmness, to compare two methods of measuring bulb firmness, and to compare bulb firmness using two different production schemes. Bulb firmness of spring-transplanted and spring-seeded intermediate-day hybrid breeding lines was measured using a digital FFF-series durometer and a subjective rating of firmness achieved by squeezing bulbs. Bulbs were rated on a scale of 1 (soft) to 9 (hard). In general, these hybrid lines produced very firm to hard onions whether the lines were transplanted or direct-seeded. Bulb firmness of these lines measured with the durometer was greater when the lines were direct-seeded (74.9) than when transplanted (73.5). Conversely, when firmness was measured with our subjective rating, transplanted onions exhibited slightly greater firmness (8.9) than direct-seeded onions (8.8). For both transplanted and direct-seeded onions, durometer readings were weakly correlated in a positive fashion with our subjective rating. In general, durometer readings gave a greater spread in firmness measurements with a range of 69.6 to 77.8 in firmness values. Subjective ratings of bulb firmness ranged from 8.5 to 9.0. Depending on the firmness of evaluated breeding lines, our subjective rating system should be adjusted to better distinguish firmness differences between bulbs.

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Maude Lachapelle, Gaétan Bourgeois, and Jennifer R. DeEll

Firmness is the main attribute that gives an indication of fruit texture and it is often used by producers to evaluate harvest date ( Trillot and Tillard, 2002 ). This quality index can be influenced by many preharvest factors such as season

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R.L. Jackman, A.G. Marangoni, and D.W. Stanley

Flat-plate compression, constant area compression, and puncture tests were examined for their sensitivity in differentiating the firmness of previously chilled (6C, 85% RH, 15 days) and nonchilled mature-green tomato (Lycopersicon esculentum Mill cv. Caruso) fruit during 10 days of ripening at 22C. Firmness, as measured by each of the three methods, progressively decreased (P < 0.001) with ripening. Previously chilled tomatoes were initially softer (P < 0.01) than nonchilled tomatoes, as measured by puncture of whole fruit and constant area compression of pericarp tissue sections, but not by flat-plate compression of whole fruit. Flat-plate compression was therefore found to be a relatively insensitive method by which to measure differences in tomato firmness that are characteristic of slightly chilling-injured fruit.

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Judith A. Abbott and D. R. Massie

Firmness is a critical quality attribute for kiwifruit, as it is for most commodities. Firmness is related to flesh elasticity and rigidity which, along with geometry and density, determine vibrational behavior. Firmness changes in kiwifruit were followed during storage at 0C by three methods: sonic vibrational spectra from 0 to 2000 Hz, dynamic force/deformation (F/D) in the range 40 to 440 Hz, and Magness-Taylor puncture (MT) on an Instron. Frequencies of sonic resonances and dynamic F/D peaks, as well as MT maximum force, decreased as storage time increased. Sonic resonance frequencies were highly correlated with MT maximum force and apparent elasticity (r=0.79 and 0.88). Frequencies of peaks in the dynamic F/D traces were correlated with MT maximum force and apparent elasticity (r=0.68 and 0.72) and with resonance frequency (r=0.81). Further data processing improves the ability of the nondestructive vibrational measurements to estimate the destructive MT test values.

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Niels O. Maness, Gerald H. Brusewitz, and T. Gregory McCollum

Variability in mesocarp firmness for peach (Prunus persica L. Batsch) fruit halves cut either parallel or perpendicular to the suture was determined for three cultivars (Halehaven, Ranger, and Topaz). Firmness evaluations were conducted using an Instron Universal testing instrument with a 3.2-mm rounded tip probe. Firmness of the inner, middle, and outer regions of the mesocarp at four angular positions around each peach half was determined at four maturity stages. Average mesocarp firmness declined with advanced stages of fruit maturity. Inner mesocarp was firmest for fruit from all three cultivars. Internal variation in firmness for the middle and outer regions of the mesocarp was highly cultivar dependent. Firmness decreased longitudinally from the stem end to the blossom end and latitudinally from the suture to the cheeks.

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Terhi Suojala-Ahlfors

Fruit firmness is one of the most important quality aspects in the production of pickling cucumbers (Cucumis sativus) for industry. This study compared the fruit firmness of different cultivars and evaluated the usability of different firmness variables. Firmness of fruit of five to six cultivars from a cultivar experiment was measured penetrometrically over 3 years. The maximum load needed to penetrate the skin, distance at maximum load, load at the end of the measurement, and the mean work during the whole measurement were recorded. Different variables gave a versatile impression of the fruit texture. Although there were some differences in the measured values each year, the ranking of the cultivars was similar each year. Cultivars Celine and Servus had the firmest skin and overall texture. `Aubade' and `Carine' had lower skin firmness but the inner part of the fruit of `Aubade' was very firm. `Etude' was similar to `Carine'. `B2590', measured in only 2 years, had lowest firmness both in skin and flesh. The results show that penetrometric measurement of fruit firmness is a suitable method for analyzing the texture of cucumbers intended for pickling.