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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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Walter Boswell, Bernard Bible, and Suman Singha

Fruit of 34 peach (Prunus persica L. Batsch). cultivars were harvested at maturity and visually evaluated by panelists on a 1 to 10 scale, where 10 = excellent color. CIELAB coordinates (L* a* b*) of fruit color were measured at the midpoint between the stem and the calyx end with a Minolta CR-200b calorimeter on the blushed and ground areas of each fruit. Simple linear regressions of color coordinates with panel ratings indicated that blush chroma, blush L*, blush hue angle and E* (total color difference between ground and blush) all influence visual color evaluation. Not only does assessing fruit color with a calorimeter permit color to be reported in internationally accepted units, but the relationships indicate that instrumental values relate well to qualitative ratings.

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Jongyun Kim, Seung Won Kang, Chun Ho Pak, and Mi Seon Kim

). Digital image analysis also provides the ability to quantify coloration of the leaves, which can improve understanding of changes in variegation ( Kwack et al., 1998 ). CIE L*a*b* (CIELAB) value is the most complete color space specified by the Commission

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Douglas V. Shaw and Erik J. Sacks

Four sets of selected strawberry (Fragaria ×ananassa Duch.) genotypes were generated from within a single breeding population to evaluate the correspondence between predicted and realized selection response for fresh fruit color traits. Genotypes were selected for extreme phenotypes, dark or light, of either internal or external color value (CIELAB L*). Genotypic selection response was evaluated empirically by scoring fruit from the clonal derivatives of these selected genotypes, and response for breeding value was estimated by scoring the offspring of crosses performed among a subset of the genotypes within each selected set. Realized selection response was slightly larger than predicted for internal and external L* when calculated for selected genotypes. Also, more than half of the selected genotypes had genotypic values for L* outside the range of the original parents, providing evidence for transgressive segregation. Realized selection response for breeding value in exterior and interior color was slightly less than predicted. Compared in a different way, genotypic selection response for external color was significantly greater than selection response for breeding value, whereas genotypic and breeding value responses did not differ for internal color. These observations suggest the presence of some nonadditive genetic variance for external color but support the conclusion that the heritabilities predicted previously were reasonably accurate. Estimates of variance components within each of the offspring populations demonstrated that genetic variances were modified substantially by one generation of selection. Selection for dark fruit color reduced genetic variance to nonsignificant levels, with internal color more affected than external color. The total genetic variances within both of the offspring populations from parents selected for light color were changed little by one generation of selection, but substantial dominance variance was detected that had not been found in the original population. The rapid response to selection and large changes in the distribution of genetic variances may indicate the presence of a few genes with comparatively large effect in strawberry color expression. Additional divergent selection response can be expected, but primarily in the direction of light fruit color.

Open access

Rebekah C.I. Maynard and John M. Ruter

option, based on ease of use. Although RHS values can be used as a standard to report the color of biological samples, variation in hues can be more easily described numerically by using the CIELAB color space ( International Commission on Illumination

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Kenneth R. Tourjee, Diane M. Barrett, Marisa V. Romero, and Thomas M. Gradziel

The variability in fresh and processed fruit flesh color of six clingstone processing peach [Prunus persica (L.) Batsch] genotypes was measured using CIELAB color variables. The genotypes were selected based on the relative fruit concentrations of β-carotene and β-cryptoxanthin. Significant (p < 0.0001) differences were found among the genotypes for the L*, a*, and b* color variables of fresh and processed fruit. Mean color change during processing, as measured by ΔELAB, was greatest for `Ross' and least for `Hesse'. A plot of the first two principal components (PCs) obtained from PC analysis of the L*, a*, and b* variables for fresh and processed fruit revealed three clusters of genotypes that match groupings based on the relative concentrations in fresh fruit of carotenoid pigments. Path analysis showed that variation in β-cryptoxanthin concentration was more precisely determined from color data than β-carotene concentration. Chemical names used: β-β-carotene (β-carotene), (3R)-β-β-caroten-3-ol (β-cryptoxanthin).

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Yiguang Wang, Chao Zhang, Bin Dong, Yaohui Huang, Zhiyi Bao, and Hongbo Zhao

English abstract) Gonnet, J.F. 1998 Colour effects of co-pigmentation of anthocyanins revisited-1. A colorimetric definition using the CIELAB scale Food Chem. 63 409 415 10.1016/S0308-8146(98)00053-3 Gouvêa, A.C.M.S. Araujo, M.C.P.D. Schulz, D.F. Pacheco

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Bernard B. Bible and Suman Singha

Differences in color development between exposed and shaded fruit during the growing season were determined for `Loring' and `Raritan Rose' peach (Prunus persica L. Batsch). The surface color of fruit exposed to sunlight in the upper canopy, and in the shade in the lower canopy, was measured with a tristimulus calorimeter, and L* a* b* values were recorded for each fruit from 17 July through harvest. Color changes (ΔE* ab) during maturation for both cultivars at either canopy position were characterized by large changes in hue (Δ H*ab) and lesser changes in lightness (Δ L*ab) and chroma (Δ C*ab). Upper canopy fruit of both cultivars were redder and darker than the lower canopy fruit initially and at harvest. Flesh firmness for `Loring' and `Raritan Rose' tended to correlate with color change from initial sampling to harvest.

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Erik J. Sacks and David M. Francis

The genetic and environmental variation for flesh color of tomato (Lycopersicon esculentum Mill.) fruit was quantified using 41 red-fruited breeding lines, open-pollinated cultivars, and hybrids that are representative of the diversity of tomatoes grown for whole-peel processing in the midwestern and eastern United States and Ontario, Canada. Objective color measurements were made for 2 years from replicated experiments with 2 to 4 blocks per year. Genotypes differed significantly in lightness value (L*), saturation (chroma), and hue angle. Variation within fruit and among fruit in plots accounted for more than 75% of the environmental variation for the color traits. The crimson locus (ogc) accounted for less than one-third of the variation in fruit color among genotypic means, and explained 18% to 27% of the genotypic variation for L*, chroma, and hue. Estimates of variance components were used to develop sampling strategies for improving selection efficiency. Genotypes were identified that may be useful for studying genetic differences that lead to quantitative variation for fruit color in red-fruited populations of tomato.