Arrakis : Relative Chlorophyll



This project is to validate the Relative Chlorophyll content measurement as part of the MultispeQ v1.0, using the initial 20 devices shipped from the factory in Nov 2016.

11 devices were calibrated it the project 4a - v1.0 FACTORY CALIBRATION. A piece of paper containing 9 squares of varying greenness and thickness, with known Minolta SPAD values, were used to calibrate the device. Those Minolta SPAD values were: 8, 17.4, 31.2, 24.4, 38.8, 47.7, 25.8, 48.6, 72 .

To validate this calibration, the devices were then taken to a greenhouse, along with a Minolta SPAD 502+ meter, and a set of 68 leaves were measured varying in thickness and greenness. For each leaf, an average of 5 Minolta SPAD values were taken and a single MultispeQ SPAD value was taken. The reason to average 5 Minolta SPAD values is the Minolta SPAD measurement area is very small (about 2.5mm x 2.5mm), while the MultispeQ measurement area is 9mm x 9mm. As a result, several Minolta readings throughout a 9mm x 9mm are needed to provide a comparable data point to a single MultispeQ reading.

See the results here


Leaf Photosynthesis MultispeQ V1.0 (development)

Change log


Updated absorbance blank and relative chlorophyll calibration intensities, which must also be updated in the absorbance section of this protocol.


Updated intensity of the "detector_read1" to 700 in accordance with the new IR LED calibration. This should output a correct baseline for phi2 and related photosynthesis data.


Changed PMF portion of trace from 300 pulses x 3 to 100 pulses x 3. Adjusted macro accordingly.


Measures photosynthesis-related parameters in <15 seconds, including: Phi2, PhiNPQ, PhiNO, NPQt, qL, LEF, and SPAD. In addition, absorbance measurements are taken at the following wavelengths - 420, 605, 650, 730, 850, 880, 950.

Also measures PAR (photosynthetically active radiation), ambient temperature/pressure/relative humidity, leaf thickness, leaf angle, leaf direction, and contactless leaf temperature.

The ECS auto-adjust feature tests the absorbance of the sample in the 525nm range (LED 1) before the measurement with 5 small pulses. Based on that value, it adjusts both the intensity of LED 1 (meas_intensity) and the size of the measurement pulse (pulsesize) during the actual measurement. These adjustments are based on testing on a series of thin, thick, green, and other colored leaves. The goal is to adjust the measuring pulse such that the detector values are in a high range (between 15k - 40k) regardless of leaf type.

This is the developm...


  1. Minolta SPAD Reading (Short Answer)
  2. Device ID (Multiple Choice)
  3. leaf colour (Multiple Choice)
  4. Plant Type (Short Answer)
  5. REP (Short Answer)




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