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Karl Guillard and John C. Inguagiato

extracts on cool-season turfgrass responses. Mature turf is at least 1 year’s growth past seeding. The Normalized Difference Vegetative Index is commonly used as an indirect, but quantitative, measure of turfgrass green color and visual quality or

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Chase M. Straw, Rebecca A. Grubbs, Kevin A. Tucker and Gerald M. Henry

grid sizes, but changes were minimal. Table 2. Correlation coefficients z between handheld and mobile data acquisitions for sampling volumetric water content (%), penetration resistance (MPa), and normalized difference vegetative index (NDVI; unit less

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James A. Hardin, Michael W. Smith, Paul R. Weckler and Becky S. Cheary

Knowledge of foliar nitrogen (N) concentration is important in pecan [Carya illinoinensis (Wang.) K. Koch] management protocols. Lower cost and/or rapid methods to determine foliar N are desirable and may result in improved management strategies as well as enable precision agricultural practices to be deployed in pecan production. This study investigates using a portable chlorophyll meter and Vis-NIR camera to rapidly determine pecan foliar N in situ. Relationships of SPAD values from a chlorophyll meter (Minolta SPAD 502Plus) and vegetative indices calculated from camera image data to foliar N determined by chemical analysis were investigated. SPAD readings were taken monthly from May through October on ‘Pawnee’, ‘Kanza’, and ‘Maramec’ pecan cultivars in Oklahoma in 2010. Images of the same ‘Pawnee’ and ‘Kanza’ trees were collected in September and October of 2010 with a truck-mounted multispectral camera using ambient light. Correlation of foliar N to SPAD values was poor in May for all cultivars but distinct significant linear relationships were found for ‘Maramec’ and ‘Pawnee’ for each of the other months tested with R 2 ranging from 0.40 to 0.87. Data from ‘Kanza’ had significant relationships in June and October with R 2 of 0.39 and 0.72, respectively. Normalized difference vegetative index (NDVI) and reflectance data extracted from Vis-NIR camera images were significantly correlated to foliar N in both months of the study on ‘Pawnee’ but only in September for ‘Kanza’. The various relationships had R 2 between 0.21 and 0.51.

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Yiwei Jiang, Huifen Liu and Van Cline

( Bell et al., 2002 ; Jiang and Carrow, 2005 ). The normalized difference vegetative index (NDVI), defined as (R NIR – R red )/(R NIR + R red ), is one of the most widely used indices for evaluating turfgrass canopy characteristics ( Jiang et al., 2003

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Yun-wen Wang, Bruce L. Dunn and Daryl B. Arnall

(CRD). Normalized Difference Vegetation Index, Soil-Plant Analyses Development value, and nitrogen content determination. Normalized Difference Vegetative Index readings were collected 42 and 48 d after initial fertilizer treatment (DAT) using a NDVI

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Jordan M. Craft, Christian M. Baldwin, Wayne H. Philley, James D. McCurdy, Barry R. Stewart, Maria Tomaso-Peterson and Eugene K. Blythe

. 2014 and 2015. Parameters evaluated included percent visual recovery, chlorophyll index, normalized difference vegetative index (NDVI), ball roll, VWC (3.8 and 7.6 cm depth), surface firmness, water infiltration, thatch-mat depth, organic matter

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Yun-wen Wang, Bruce L. Dunn, Daryl B. Arnall and Pei-sheng Mao

turfgrass chlorophyll content and tissue nitrogen HortScience 39 1130 1132 Biamonte, R.L. Holcomb, E.J. White, J.W. 1993 Fertilization 39 54 White J.W. Geraniums IV Ball Publishing Batavia, IL Carrillo, T. 2006 Normalized difference vegetative index

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Amir Ali Khoddamzadeh and Bruce L. Dunn

chlorophyll content and tissue nitrogen HortScience 39 1130 1132 Blackmer, T.M. Schepers, J.S. 1995 Use of a chlorophyll meter to monitor nitrogen status and schedule fertigation for corn J. Prod. Agr. 8 56 60 Carrillo, T. 2006 Normalized difference vegetative

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Richard Smith, Michael Cahn, Timothy Hartz, Patricia Love and Barry Farrara

was greater than K e , T was used as the K c . Images taken by a digital camera (Rebel T5i 700D 18.1 Megapixel; Canon Inc., Melville, NY), modified to take normalized difference vegetated index images (LDP-LLC MaxMax Inc., Carlstadt, NJ), were used

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Sarah E. Cathey, Jason K. Kruse, Thomas R. Sinclair and Michael D. Dukes

reflectance were monitored through measurement of the normalized difference vegetative index (NDVI) using a Field Scout TCM 500 NDVI Color Meter (Spectrum Technologies, Plainfield, IL). Visual rating of firing and wilting was recorded as a percentage of the