1. NDVI: What It Is and What It Measures Danielle Williams

2. What is NDVI? ; Normalized difference vegetation index ; mathematical formula derived to form a single spectral based number l 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 l less time l more cost effective l more precise application of fertilizer l 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???