a b

Figure 1. Royal Horticultural Society Color Chart (a) and Colorimeter Minolta CR-400 (b).

a b Figure 2. CIELAB color space (a) and (b) a*b* chromaticity diagram. The measurements from the colorimeter could allow the identification of a cultivar by any single attribute (L*a*b*value, chroma or hue) so that color differences may be noted more specifically. The ability to accurately describe a cultivar’s color greatly enhances the informational content of the data. For example, the flowers of “AM121” and “121-1” have the similar L* a* and chroma but different b* and hue values (Table 1). However, using the colorimeter values for the RHSCC (Chip 61B) the values were significantly different for all parameters but hue angle (data not shown). The colorimeter ability to more accurately dissect color also helps in resolving disputes of a cultivar’s specific color. We have found that in most instances of a variance in color evaluation, the colorimeter has quickly resolved the differences in opinion. This is more difficult with the color charts.

141