Quantifying Turfgrass Color Using Digital Image Analysis

Karcher, Douglas E.; Richardson, Michael D.

doi:10.2135/cropsci2003.9430

Cited by 308 publications

(292 citation statements)

References 9 publications

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“…Each digital image covered an area of 0.9 by 1.1 m and measurements were averaged over the two photographs. A 92 cm (length) by 61 cm (width) by 61 cm (height) metal box equipped on the inside with four 9 Watt lamps was used to provide uniform lighting conditions for all the digital images taken (Ikemura, 2003;Karcher and Richardson, 2003). A Canon A570is (Canon Inc., Tokyo, Japan) camera was set to a shutter speed of 1/60, an aperture of f/2.6, ISO 200, and a focal lens of 32 mm.…”

Section: Methodsmentioning

confidence: 99%

Surfactant and Polymer‐Coated Sand Effects on Deficit Irrigated Bermudagrass Turf

et al. 2016

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Sand topdressing and soil surfactants are commonly applied to turfgrass areas but it is unclear whether these practices improve visual appearance or reduce hydrophobicity under defi cit irrigation. A study was conducted from 2011 to 2013 at New Mexico State University in Las Cruces, NM, to evaluate two topdressing materials and a soil surfactant on defi cit irrigated Princess 77 bermudagrass (Cynodon dactylon L.) grown on a loamy sand (mixed, thermic Typic Torripsamment). Treatments consisted of monthly applications of a polymer-coated hydrophilic sand (ACA 3114) or straight sand with or without the soil surfactant and an untreated control. Plots were mowed at 2.0 cm and irrigated at either 70 or 50% of reference evapotranspiration for short grass (ET os ). When results were averaged over the research period, plots irrigated at 50% ET os and receiving ACA 3114 or sand topdressing and the soil surfactant exhibited greater green coverage (85.3 and 88.2%, respectively) and better turfgrass quality (6.6 and 6.5, respectively, with 1 = worst, 9 = best) than control plots (71.6% green coverage, quality = 5.1) or plots receiving sand topdressing only (74.7% green coverage, quality = 5.3). Soil repellency in the upper root zone was detected only in 2011, and applications of both ACA 3114 and straight sand topdressing with the soil surfactant on plots irrigated at 50% ETos resulted in lower water drop penetration times (7s and 1s) compared to sand topdressing (12s) only. Our results suggest that bermudagrass quality can be maintained under defi cit irrigation if either topdressed with a hydrophilic sand or with straight sand combined with a surfactant.

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Section: Methodsmentioning

confidence: 99%

Surfactant and Polymer‐Coated Sand Effects on Deficit Irrigated Bermudagrass Turf

et al. 2016

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“…Digital image analysis was used to evaluate percent green cover. Images taken on 15 November of each year were analyzed using SigmaScan Pro 5 (Systat Software Inc., San Jose, CA) (Karcher and Richardson, 2003). Volumetric water content from 0 to 7.5 cm depths was recorded monthly.…”

Section: 1mentioning

confidence: 99%

Plant Growth Regulator and Soil Surfactants’ Effects on Saline and Deficit Irrigated Warm‐Season Grasses: I. Turf Quality and Soil Moisture

et al. 2014

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A study was conducted at New Mexico State University in Las Cruces, NM, from 2010 to 2012 to investigate the effects of deficit irrigation on bermudagrass (Cynodon dactylon L.) cultivar Princess 77 and seashore paspalum (Paspalum vaginatum Swartz) cultivar Sea Spray treated with either soil surfactants [Revolution (modified methyl capped block copolymer) or Dispatch (alkyl polyglucoside blended with a straight block copolymer)] or a plant growth regulator [Trinexapac‐ethyl (TE); 4‐(cyclopropylhydroxymethylene)‐3,5‐dioxocyclohexanecarboxylic acid]. Irrigation was applied daily at 50% reference evapotranspiration from either a sprinkler or a subsurface drip system with either potable (electrical conductivity [EC] = 0.6 dS m−1) or saline (2.3 dS m−1) water. Normalized Difference Vegetation Index (NDVI) and visual ratings were determined monthly to assess stand quality and turf stress. Princess 77 treated with TE showed the highest quality and the highest NDVI (0.655) on 10 out of 15 sampling dates. Positive effects of TE applications were also observed on Sea Spray quality, NDVI, and fall color retention. Subsurface drip irrigation resulted in higher quality and NDVI during the third year of the study when compared with sprinkler irrigation. Salinity buildup in the root zone did not negatively affect visual quality of the tested warm‐season species. Generally, sprinkler irrigation system and turf treated with Revolution promoted higher water distribution uniformity (lower standard deviations) than the other treatments. Further research is needed to investigate if greater drought tolerance of subsurface drip–irrigated turf is the result of increased water‐use efficiency due to altered root morphology.

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“…The camera records the image, and special software analyzes the image by measuring the greenness of the leaf based on red, green, blue (RGB) colors of the picture. The RGB values are converted into hue, saturation and brightness values using a method described by Karcher and Richardson [70] to calculate the Dark Green Color index (DGCI):…”

Section: The Dark Green Color Index (Dgci)mentioning

confidence: 99%

Section: The Dark Green Color Index (Dgci)mentioning

confidence: 99%

“…Karcher and Richardson [70] and Rorie et al [23] found DGCI an accurate tool to estimate N leaf concentration in turfgrass and maize, respectively. For example, Rorie et al [23] quantified maize leaf greenness with a digital camera and image analysis software (Sigma Scan Pro 5, SPSS, 1998, San Jose, CA, USA) in terms of DGCI by modifying the digital-imaging method of Karcher and Richardson [70]. Rorie et al [23] photographed the ear leaf of maize at tasseling against a pink board (to provide contrast in subsequent image processing) that had two internal color standards disks with known DGCI values (0.5722 for the green disk and 0.073 for the yellow disk).…”

Section: The Dark Green Color Index (Dgci)mentioning

confidence: 99%

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Nitrogen (N) Mineral Nutrition and Imaging Sensors for Determining N Status and Requirements of Maize

Rhezali¹,

Lahlali

2017

J. Imaging

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Nitrogen (N) is one of the most limiting factors for maize (Zea mays L.) production worldwide. Over-fertilization of N may decrease yields and increase NO 3 − contamination of water.However, low N fertilization will decrease yields. The objective is to optimize the use of N fertilizers, to excel in yields and preserve the environment. The knowledge of factors affecting the mobility of N in the soil is crucial to determine ways to manage N in the field. Researchers developed several methods to use N efficiently relying on agronomic practices, the use of sensors and the analysis of digital images. These imaging sensors determine N requirements in plants based on changes in Leaf chlorophyll and polyphenolics contents, the Normalized Difference Vegetation Index (NDVI), and the Dark Green Color index (DGCI). Each method revealed limitations and the scope of future research is to draw N recommendations from the Dark Green Color Index (DGCI) technology. Results showed that more effort is needed to develop tools to benefit from DGCI.

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Quantifying Turfgrass Color Using Digital Image Analysis

Cited by 308 publications

References 9 publications

Surfactant and Polymer‐Coated Sand Effects on Deficit Irrigated Bermudagrass Turf

Surfactant and Polymer‐Coated Sand Effects on Deficit Irrigated Bermudagrass Turf

Plant Growth Regulator and Soil Surfactants’ Effects on Saline and Deficit Irrigated Warm‐Season Grasses: I. Turf Quality and Soil Moisture

Nitrogen (N) Mineral Nutrition and Imaging Sensors for Determining N Status and Requirements of Maize

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