Table 4.
Correlation coefficients between summer corn canopy nitrogen concentration and spectral index (two years).
| Spectral Index | Whole Growth Period | Jointing Period | Tasseling Period | Filling Period | Maturity Period | |
|---|---|---|---|---|---|---|
| 1 | Green peak amplitude, Rg | −0.344 | −0.509 | 0.345 | 0.025 | −0.167 |
| 2 | Red trough amplitude, Rr | −0.542 | −0.421 | 0.533 | −0.407 | −0.167 |
| 3 | (Rg – Rr)/(Rg + Rr) | 0.743 | 0.004 | −0.680 | 0.460 | 0.054 |
| 4 | Rg/Rr | 0.716 | 0.026 | −0.668 | 0.437 | 0.043 |
| 5 | Red trough skewness, Sr | 0.087 | 0.278 | 0.075 | 0.355 | 0.333 |
| 6 | Red trough kurtosis, kr | −0.243 | 0.242 | 0.023 | −0.066 | 0.297 |
| 7 | Green peak skewness, Sg | −0.407 | −0.285 | −0.236 | −0.669 | 0.535 |
| 8 | Green peak kurtosis, kg | 0.534 | 0.301 | 0.257 | 0.549 | −0.574 |
| 9 | Sg/Sr | −0.078 | 0.206 | −0.134 | −0.131 | 0.389 |
| 10 | kg/kr | 0.398 | −0.082 | 0.213 | 0.215 | −0.443 |
| 11 | (Sg – Sr)/(Sg + Sr) | 0.283 | −0.251 | −0.118 | −0.107 | 0.016 |
| 12 | (kg – kr)/(kg + kr) | 0.355 | −0.087 | 0.215 | 0.184 | −0.468 |
| 13 | depth670 | 0.701 | 0.325 | −0.122 | 0.529 | 0.286 |
| 14 | Area670 | −0.349 | −0.506 | 0.414 | 0.031 | −0.145 |
| 15 | ND670 | 0.603 | 0.378 | −0.264 | 0.544 | 0.268 |
| 16 | Red edge amplitude, Dr | 0.498 | −0.300 | 0.557 | 0.542 | 0.035 |
| 17 | Blue edge amplitude, Db | 0.167 | −0.434 | 0.065 | 0.086 | −0.229 |
| 18 | Yellow edge amplitude, Dy | −0.571 | 0.565 | 0.231 | −0.357 | 0.140 |
| 19 | Red edge area, SDr | 0.706 | −0.290 | 0.471 | 0.479 | 0.231 |
| 20 | Blue edge area, SDb | 0.044 | −0.514 | −0.145 | −0.074 | −0.236 |
| 21 | Yellow edge area, SDy | −0.612 | 0.481 | −0.237 | −0.348 | −0.244 |
| 22 | SDr/SDb | 0.605 | 0.370 | 0.621 | 0.638 | 0.516 |
| 23 | SDr/SDy | 0.108 | −0.380 | −0.045 | 0.526 | 0.016 |
| 24 | SDr – SDb | 0.741 | −0.181 | 0.527 | 0.520 | 0.353 |
| 25 | (SDr – SDb)/(SDr + SDb) | 0.608 | 0.419 | 0.602 | 0.678 | 0.538 |
| 26 | (SDr – SDy)/(SDr + SDy) | 0.612 | −0.429 | −0.106 | 0.306 | 0.275 |
| 27 | NPCI | 0.773 | −0.149 | 0.740 | 0.734 | 0.313 |
| 28 | PRIb | −0.782 | −0.321 | −0.399 | −0.563 | −0.243 |
| 29 | Soil adjustment vegetation index, SAVI | 0.762 | −0.098 | 0.410 | 0.523 | 0.327 |
| 30 | RVI (950,660) | 0.694 | 0.314 | −0.028 | 0.496 | 0.293 |
| 31 | RVI (810,660) | 0.693 | 0.313 | −0.135 | 0.519 | 0.292 |
| 32 | NRI = R800/R550 | 0.612 | 0.368 | 0.188 | 0.496 | 0.423 |
| 33 | RVI (810, 560) | 0.611 | 0.371 | 0.259 | 0.514 | 0.412 |
| 34 | DCNI | 0.453 | 0.420 | 0.293 | 0.330 | 0.425 |
| 35 | MSR sum | 0.754 | 0.359 | 0.225 | 0.615 | 0.425 |
| 36 | MSR mean | 0.754 | 0.359 | 0.226 | 0.615 | 0.424 |
| 37 | ND (FD730,FD525) | 0.680 | 0.477 | 0.624 | 0.682 | 0.543 |
| 38 | ND (573, 440) | 0.195 | −0.052 | −0.810 | −0.892 | −0.453 |
| 39 | R810 – R680 | 0.613 | −0.255 | 0.473 | 0.476 | 0.205 |
| 40 | RVI (780, 740) | 0.687 | 0.372 | 0.637 | 0.718 | 0.522 |
| 41 | RVI (760, 510) | 0.611 | 0.328 | −0.283 | 0.346 | 0.248 |
| 42 | RVI (760, 460) | 0.604 | 0.318 | −0.474 | 0.175 | 0.203 |
| 43 | ND (760, 510) | 0.702 | 0.315 | −0.339 | 0.372 | 0.286 |
| 44 | ND (740, 460) | 0.610 | 0.266 | −0.603 | 0.013 | 0.170 |
| 45 | RSI (FD691, FD711) | −0.612 | −0.586 | −0.409 | −0.539 | −0.478 |
| 46 | CCCI | 0.615 | 0.412 | 0.694 | 0.703 | 0.547 |
| 47 | NDRE | 0.771 | 0.390 | 0.524 | 0.735 | 0.569 |
| 48 | mNDVI = (R816 – R732 – R537) /(R816 + R732 + R537) |
0.704 | 0.384 | 0.444 | 0.590 | 0.468 |
| 49 | BNI | 0.402 | 0.018 | −0.113 | 0.569 | 0.145 |
| 50 | mNDVI = (R924 – R703 + 2 × R423) (R924 + R703 – 2 × R423) |
0.738 | 0.451 | 0.799 | 0.864 | 0.538 |
| 51 | R′729 | 0.767 | −0.031 | 0.593 | 0.607 | 0.458 |
| 52 | RNIR – RRED MAX | −0.402 | 0.276 | 0.609 | 0.039 | 0.080 |
| 53 | RNIR – RRED MIN | −0.297 | −0.512 | −0.241 | −0.176 | −0.279 |
| 54 | RNIR – RRED sum | 0.352 | −0.342 | 0.498 | 0.420 | 0.029 |
| 55 | RNIR – RRED mean | 0.606 | −0.181 | 0.511 | 0.485 | 0.226 |