Table 6.
Correlation coefficients between corn canopy nitrogen concentration and spectral indexes (two years).
| Spectral Index | Whole Growth Period | Jointing Period | Tasseling Period |
Filling Period | Maturity Period |
|---|---|---|---|---|---|
| mNDVI = (R924 − R703 + 2 × R423) /(R924 + R703 − 2 × R423) |
0.771 ** | 0.451 * | 0.799 ** | 0.864 ** | 0.569 ** |
| NDRE = (R780 − R720)/(R780 + R720) | 0.738 ** | 0.390 | 0.524 * | 0.735 ** | 0.538 ** |
| R780/R740 | 0.687 ** | 0.372 | 0.637 ** | 0.718 ** | 0.522 ** |
| ND(FD730, FD525) = (R′730 − R′525)/(R′730 + R′525) |
0.680 ** | 0.477 * | 0.624 ** | 0.682 ** | 0.543 ** |
| CCCI = ((R780 − R720)/(R780 + R720))/ ((R780 − R670)/(R780 + R670)) |
0.615 ** | 0.412 | 0.694 ** | 0.703 ** | 0.547 ** |
Note: ** p < 0.01, * p < 0.05.