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Relationships between Blue- and Red-based Vegetation Indices and Leaf Area and Yield of Alfalfa

^a Dep. of Biosystems and Agricultural Engineering, Univ. of Kentucky, Lexington, KY 40546
^b Dep. of Plant and Soil Sciences, Univ. of Kentucky. Submitted with the approval of the Director, KY Agric. Exp. Stn. as publication 07-99-006

View larger version (33K): [in this window] [in a new window]   Figure 1. Relationship of the blue- and red-based normalized difference vegetation indices (NDVIs) to leaf area index (LAI), mass shoot–1, and shoot length. At each of the final four harvests in 2005, 20 LAI measurements and 40 mass shoot–1 and shoot length observations were taken from each harvested plot.

View larger version (34K): [in this window] [in a new window]   Figure 2. Relationship of red-based wide dynamic range vegetation indices (WDRVIs) at ‘’ levels of 0.1, 0.05, and 0.01 to leaf area index (LAI), mass shoot–1, and shoot length. At each of the final four harvests in 2005, 20 LAI measurements and 40 mass shoot–1 and shoot length observations were taken from each harvested plot.

View larger version (35K): [in this window] [in a new window]   Figure 3. Relationship of blue-based wide dynamic range vegetation indices (WDRVIs) at ‘’ levels of 0.1, 0.05, and 0.01 to leaf area index (LAI), mass shoot–1, and shoot length. At each of the final four harvests in 2005, 20 LAI measurements and 40 mass shoot–1 and shoot length observations were taken from each harvested plot.

View larger version (13K): [in this window] [in a new window]   Figure 4. Quadratic-plateau functions describing the relationship between alfalfa yield and normalized difference vegetation index (NDVI) as measured by the GreenSeeker (NDVIGS) and FieldScan (NDVIFS). Canopy reflectance measurements were made 1 d before each of the five harvests during 2005. Observations for a given harvest consist of the mean VI and total plot yield measured from each plot (n = 80).

View larger version (22K): [in this window] [in a new window]   Figure 5. Quadratic-plateau functions describing the relationship between alfalfa yield and wide dynamic range vegetation indices (WDRVIs) calculated using one of three near-infrared (NIR) reflectance-scalars (‘’ = 0.1, 0.05, and 0.01). Canopy reflectance measurements from which the indices are calculated were made 1 d before each of the five harvests during 2005 using the FieldScan. Observations for a given harvest consist of the mean VI and total plot yield measured from each plot (n = 80).

View larger version (26K): [in this window] [in a new window]   Figure 6. Quadratic-plateau functions describing the relationship between alfalfa yield and blue-based vegetative indices (blue normalized difference vegetation index [BNDVI] and blue-wide dynamic range vegetation indices [BWDRVIs] calculated using one of three near-infrared [NIR] reflectance-scalars [‘’ = 0.1, 0.05, and 0.01]). Canopy reflectance measurements from which the indices are calculated were made 1 d before each of the five harvests during 2005 using the FieldScan. Observations for a given harvest consist of the mean VI and total plot yield measured from each plot (n = 80).