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  • Author or Editor: S. Singha. x
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The objective of this study was to determine the difference in color development between exposed and shaded fruit of `Loring' and `Raritan Rose' peach (Prunus persica L. Batsch). Chromaticity values (L* a* b*) were measured with a Minolta CR-200b colorimeter on 10 tagged fruit on each of 3 trees of each cultivar. Five fruit were fully exposed to sunlight and 5 were shaded. Measurements were made on each fruit from July 17, 1991 through harvest. Differences in the a*/b* ratio between shaded and exposed fruit were observed at the first sampling date and increased towards maturation; shaded fruit approached a*/b* values similar to exposed fruit at a significantly later time. Shading reduced relative fruit color development more in `Loring' than in `Raritan Rose'.

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Portable tristimulus colorimeters allow precise documentation of color of horticultural commodities and their usage in research is increasing. This laboratory exercise was designed to familiarize students with CIELAB color space coordinates and the relationship between quantitative values and visual color ratings. Students measured L* a* b* coordinates and used these values to compute and comprehend derivatives including hue angle, chroma and color difference. These concepts were demonstrated using readily available materials including bananas at different stages of maturation, apples harvested from different canopy locations, and variations in rate of oxidative browning of the flesh of apples stored at different temperature. To develop an appreciation for both quantitative and qualitative color measurements leaves of varying color were visually rated, matched to Royal Horticultural Society color charts and L* a* b* values measured with a Minolta CR-200b Chroma Meter.

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The objective of this study was to determine the relationship between temperature and color development in 3 strains of Red Delicious apple (Malus domestica Borkh). The strains `Scarlett Spur', `Ultrastripe' and `Starkrimson' were chosen based on variation in coloration. Chromaticity values (L* a* b*) were measured with a Minolta CR-200b calorimeter on 5 tagged apples on each of 4 trees of each strain. Measurements were made at approximately the same location on each fruit 23 times from July 11 through September 25, 1989. Differences in a*/b* ratio among strains were observed as early as the first sampling date; with `Scarlet Spur' having the highest ratio and `Starkrimson' the lowest. These differences were maintained for most the growing season. Temperature below 21C tended to enhance color development, whereas temperature above 21C reduced coloration. Temperature affected all 3 strains similarly.

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The objective of this study was to determine the relationship between temperature and color development in 3 strains of Red Delicious apple (Malus domestica Borkh). The strains `Scarlett Spur', `Ultrastripe' and `Starkrimson' were chosen based on variation in coloration. Chromaticity values (L* a* b*) were measured with a Minolta CR-200b calorimeter on 5 tagged apples on each of 4 trees of each strain. Measurements were made at approximately the same location on each fruit 23 times from July 11 through September 25, 1989. Differences in a*/b* ratio among strains were observed as early as the first sampling date; with `Scarlet Spur' having the highest ratio and `Starkrimson' the lowest. These differences were maintained for most the growing season. Temperature below 21C tended to enhance color development, whereas temperature above 21C reduced coloration. Temperature affected all 3 strains similarly.

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