Table 2.
Statistical results of the relationships across the whole set of plots (288), as well as across the set of plots of each trial (72) between grain yield and the ear counting using the algorithm (ears/m2) in the first, second and third date of measurement as well as the manual in situ counting
| Determination coefficient (R2), Pearson correlation (r) and mean (μ) ± standard deviation for NDVI | First measurement | Second measurement | Third measurement | Manual in situ counting |
|---|---|---|---|---|
| Whole dataset (288) | R2 = 0.30*** | R2 = 0.08*** | R2 = 0.05*** | R2 = 0.24*** |
| r = 0.55*** | r = 0.28*** | r = 0.21*** | r = 0.49*** | |
| Aranjuez Irrigated Dataset (72) |
R2 = 0.05ns | R2 = 0.05ns | R2 = 0.02ns | R2 = 0.18** |
| r = 0.22ns | r = -0.04ns | r = 0.14ns | r = 0.43** | |
| μ = 0.78 ± 0.03 | μ = 0.71 ± 0.07 | μ = 0.29 ± 0.14 | ||
| Aranjuez Rainfed Dataset (72) |
R2 = 0.05ns | R2 = 0.02ns | R2 = 0.02ns | R2 = 0.53*** |
| r = 0.22ns | r = 0.16ns | r = 0.14ns | r = 0.73*** | |
| μ = 0.76 ± 0.02 | μ = 0.67 ± 0.04 | μ = 0.17 ± 0.11 | ||
| Valladolid Irrigated Dataset (72) |
R2 = 0.06* | R2 = 0.0049ns | R2 = 0.06* | R2 = 0.01ns |
| r = − 0.24* | r = − 0.07ns | r = 0.25* | r = 0.07ns | |
| μ = 0.73 ± 0.03 | μ = 0.67 ± 0.05 | μ = 0.45 ± 0.10 | ||
| Valladolid Rainfed Dataset (72) |
R2 = 0.07* | R2 = 0.05ns | R2 = 0.18*** | R2 = 0.05* |
| r = 0.26* | r = 0.22ns | r = 0.43*** | r = 0.23* | |
| μ = 0.66 ± 0.04 | μ = 0.41 ± 0.05 | μ = 0.18 ± 0.14 |
The mean (μ) ± standard deviation of the normalized difference vegetation index (NDVI) values, across the whole set of plots within each trial is also included for reference
ns no significant
*p value < 0.05; **p value < 0.01; ***p value < 0.001