Table 3.
Equations to convert measurement units of different chlorophyll meters.
| Chlorophyll meter | Equation | Regression | R2 | ±SEE | n |
|---|---|---|---|---|---|
| SPAD-502 | SPAD = 0.622 × atLEAF1.136 | Power | 0.86 | 4.65 | 713 |
| SPAD = 13.302 × CCI0.360 | Power | 0.95 | 2.96 | 660 | |
| SPAD = 2.587 + 29.603 × SFR_G – 2.747 × SFR_G2 | Quadratic | 0.88 | 4.37 | 713 | |
| atLEAF+ | atLEAF = -6.907 + 1.647 × SPAD – 0.010 × SPAD2 | Quadratic | 0.91 | 2.88 | 713 |
| atLEAF = 4.897 + 12.309 × ln(CCI) | Logarithm | 0.90 | 3.22 | 666 | |
| atLEAF = 1.838 + 34.920 × SFR_G – 5.222 × SFR_G2 | Quadratic | 0.88 | 3.34 | 719 | |
| MC-100 | CCI = 0.001337 × SPAD2.639 | Power | 0.92 | 8.15 | 660 |
| CCI = 0.000405 × atLEAF2.988 | Power | 0.71 | 15.22 | 666 | |
| CCI = 9.973 × SFR_G2.003 | Power | 0.82 | 12.18 | 667 | |
| Multiplex | SFR_G = -0.522 + 0.063 × SPAD – 0.000178 × SPAD2 | Quadratic | 0.87 | 0.23 | 713 |
| SFR_G = -0.560 + 0.056 × atLEAF | Linear | 0.80 | 0.28 | 719 | |
| SFR_G = -0.602 + 0.775 × ln(CCI) | Logarithm | 0.89 | 0.21 | 667 | |
Coefficient of determination (R2), standard error of the estimate (±SEE) and sample size (n) of the regression are shown. CCI is chlorophyll content index, measured with the MC-100 meter; SFR_G is the Simple Fluorescence Ratio under green excitation, measured with the Multiplex sensor.