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NDVI: What It Is and What It Measures

NDVI: What It Is and What It Measures. Danielle Williams. What is NDVI?. Normalized difference vegetation index mathematical formula derived to form a single spectral based number more sensitive than just a single wavelength ratio - no units. What does NDVI measure? .

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NDVI: What It Is and What It Measures

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  1. NDVI: What It Is and What It Measures DanielleWilliams

  2. What is NDVI? • Normalized difference vegetation index • mathematical formula derived to form a single spectral based number • more sensitive than just a single wavelength • ratio - no units

  3. What does NDVI measure? • “greenness” i.e. chlorophyll content • correlated with biomass • represent N status of plant

  4. How does it work? • Light • -absorbed • -transmitted • -reflected • Different pigments stimulated by • different parts of light spectrum

  5. NDVI= IR-Red / IR+ Red IR 750-1300 nm Red 600-700nm Chlorophyll greenness of leaf - activity @ 645 and 663nm Reflected green color peaks at 550nm

  6. Uses of NDVI • water stress • N stress/uptake • P stress/ uptake • Anything if it is the limiting/excess factor • disease?

  7. Factors affecting NDVI • leaf morphology • growth stage (Sembiring et al, 2000) • variety (Sembiring et al. ,2000) • crop • row spacing/planting density (Lukina et al, 2000) • soil type (Heilman and Kress, 1987) • canopy cover • environmental stress

  8. Why use NDVI? • indirect measurement • less time • more cost effective • more precise application of fertilizer • unbiased

  9. NDVI over duration of season(Mahey et al. 1991)

  10. Future research • other nutrients other than N • calibrations for crops • disease

  11. Questions???

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