A Comparison of Visual vs. Instrumental Measurement of Color Differences in Bentgrass Turf

Abstract

<jats:p>This study was conducted to determine: 1) if the Minolta CR-310 Chroma Meter can detect color differences among bentgrass (<jats:italic>Agrostis stolonifera</jats:italic> L., <jats:italic>A. capillaris</jats:italic> L.) cultivars maintained as a turf; 2) how the CR-310 parameters of hue angle, lightness, and chroma compare with visual color assessments; and 3) if the CR-310 can provide consistent color measurements among evaluators. Differences were detected among cultivars with respect to hue angle, lightness, and chroma. Hue angle and chroma were significantly correlated with visual color assessments when data were averaged across all evaluators. Lightness was not strongly associated with visual color assessment. Differences were found among evaluators for visual color assessment, lightness, and chroma, but not for hue angle measurements. Thus, hue angle appears to be the most consistent CR-310 parameter for measuring color of bentgrass turf. These results indicate that the CR-310 can be used to evaluate the color of bentgrass cultivars maintained as a turf and provides consistent hue angle measurements among evaluators, regardless of experience in rating turf color. The CR-310 is probably best used for measuring relative color differences and may be useful if cultivars of similar color are desired in blended turfs.</jats:p>

Evaluation of Key Methodology for Digital Image Analysis of Turfgrass Color Using Open‐Source Software

“…Using hue angle to quantify turf color has been suggested before. Studies with perennial ryegrass and creeping bentgrass found that, in situ, hue angle measured by a ChromaMeter (Minolta Co., Ramsey, NJ) served as a consistent and effective color indicator (Thorogood et al, 1993; Landschoot and Mancino 2000). The extremely small sampling areas dictated by the ChromaMeter sensor head, however, precluded its wider application for larger plot studies.…”

Turfgrass (Cynodon dactylon L.) sod production on sandy soils: I. Effects of irrigation and fertiliser regimes on growth and quality

“…Turfgrass colour was measured one day before summer harvests and five days before winter harvests using a Chroma Meter (Minolta, CR-310, Osaka, Japan), an instrument previously shown to enable quantitative assessments of turfgrass colour (Landschoot and Mancino, 2000). The meter describes colour in three coordinates: L*, lightness, from 0 (black) to 100 (white); a*, from )60 (green) to 60 (red); and b*, from )60 (blue) to 60 (yellow).…”

“…The meter describes colour in three coordinates: L*, lightness, from 0 (black) to 100 (white); a*, from )60 (green) to 60 (red); and b*, from )60 (blue) to 60 (yellow). As recommended by Landschoot and Mancino (2000), data used to assess turf greenness were the hue angles for the CIELAB colour space (Hamill and Camlin, 1984). At any level of lightness, the hue angle is calculated as arctangent (b*/a*) and was used to describe the colour of the turfgrass; the greater the hue angle the darker the greenness of the turfgrass.…”

Granular wetting agents ameliorate water repellency in turfgrass of contrasting soil organic matter content

“…Turfgrass quality was assessed by measuring turfgrass colour and tissue (clippings) N concentration of each plot. Turfgrass colour was measured prior to commencing the experiment, and then every 4 weeks, using a Chroma Meter (Minolta, CR-310, Osaka, Japan); an instrument previously shown to enable quantitative assessments of turfgrass colour (Barton and Colmer 2006;Landschoot and Mancino 2000). Each turfgrass plot was divided into eight subplots (0.56 m 2 ), which did not include turfgrass within 0.5 m of each edge, which were then further divided into nine (0.0625 m 2 ) sampling squares using a sampling grid made from tensioned rope held by rods on each side.…”