*3.4. Relationships between Vegetation Indices and Productivity*

While comparing the influences of the vegetation indices (EVI and NDVI) on the yield of the irrigated Airport field and the non-irrigated Baxter field, no significant relationship was found between the yield and growing season EVI and NDVI for the Airport and Baxter wild blueberry fields during the prune and crop year (Figures 9 and 10). The only significant correlation was found between the mean EVI of the prune year and crop year for the Airport field and its yield when fitted with the quadratic relationship (R2 = 0.65, *p* = 0.03), whereas the correlation between the mean NDVI of the prune year and crop year for the Airport field and its yield was non-significant.

**Figure 9.** Relationship between wild blueberry yield (lbs./acre) and the average enhanced vegetation index (EVI) of (**a**,**b**) the prune year, (**c**,**d**) the crop year, and (**e**,**f**) the average of the prune and crop year from the Airport (irrigated) and Baxter (non-irrigated) fields in Deblois, Maine. The dashed red lines indicate significant (*p* < 0.05) or marginally significant (*p* < 0.10) quadratic relationships.

**1'9,**

**Figure 10.** Relationship between wild blueberry yield (lbs./acre) and the average normalized difference vegetation index (NDVI) of (**a**,**b**) the prune year, (**c**,**d**) the crop year, and (**e**,**f**) the average of the prune and crop year from the Airport (irrigated) and Baxter (non-irrigated) fields in Deblois, Maine.
