AP4 Leaf Porometer features
The AP4 Leaf Porometer measures diffusion conductance by comparing the precise rate of humidification within a small cuvette (chamber) to readings obtained with a calibration plate. The plate has 6 diffusion conductance settings whose values have been accurately determined by finite element analysis.
Quoted accuracy figures for other porometers and gas analysis systems are based on time-consuming laboratory set-up and calibrations which bear little comparison to field conditions. In contrast, the AP4 Leaf Porometer features simple direct calibration in the field against a tested physical standard.
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Parameter |
Reading range |
Resolution [1] |
Accuracy [2] |
Test conditions [5]
Reading range |
Conductance |
5.0 -1200 mmol m-2 s-1 |
0.1 – 10 |
± 10 % |
5 – 800 mmol m-2 s-1 |
± 20 % |
800 – 1200 mmol m-2 s-1 |
Conductance |
0.25 – 30.0 mm s-1 |
0.01 – 0.1 |
± 10% |
0.25 – 20 mm s-1 |
± 20 % |
20-30 mm s-1 |
Resistance |
0.2 – 40 s cm-1 |
0.01 – 0.1 |
± 10 % |
0.5 – 40 s cm-1 |
± 0.2 s cm-1 |
0.2 – 0.5 s cm-1 |
RH |
0 – 100% |
0.1 |
± 4% |
|
Cup temp |
-5 – +55 °C |
0.1 |
± 0.7 °C |
0 – 50 °C |
Cup-leaf temp |
-5 – +5 °C |
0.1 |
± 0.2 °C |
0 – 50 °C |
PAR flux [3] |
0 – 2500 µmol m-2 s-1 |
10 |
± 15% |
|
Pressure [4] |
600 – 1200 hPa, settable in steps of 5 hPa |
|
RH cycle level |
20 – 80 %RH, settable in steps of 5% |
|
[1] Resolution varies with the magnitude of the value obtained. The range shown corresponds to the reading range. In relative terms, the resolution is better than 2%, but at least the smallest amount shown.
[2] The stated accuracy applies over the range of the calibration plate and for optimum cup conditions, i.e. from +10 to -5 °C difference between actual cup temp. and that existing at calibration, and for +2.5 to -2.5 °C difference between leaf and cup temperatures.
[3] Spectral and cosine responses are approximate only.
[4] Ambient pressure may be read from a Wristwatch Barometer type PBR1.
[5] Cycling at extreme combinations of temperature, conductance and RH level may not always be possible.
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