Methods of Data Collection
How you collect data can have a big effect on the quality of that data, learn different methods we suggest here!
- Many of the MultispeQ parameters are dependent on incoming light and time of day.
- These include PAR, Phi2, PhiNPQ, etc...
- One single person cannot collect all their plant data outdoors under a single light condition.
- If you measure your first plant in the morning, and the last at noon, your conditions are totally different.
- One might assume the differences are in the plant, when they could simply be the ambient light levels!
- One way to combat this is to measure each plant at multiple times in a day.
- If you have two or more people walking in the field, all starting from different points, you will measure plants at different light intensities
- This will allow you to have a better "average" and more comparable results.
- If you are in a field measuring rows that all have different treatments, it would be best not to measure one row all at once.
- Measure one plant from one treatment, and move on to the next.
- This is the same idea of trying to average out your results so the differences you might see are actually from the treatment, and not poor data collecting technique.
Best Measurement Practices
Following these few steps will help ensure all your measurements are of the highest quality.
- Position yourself so you are not shading the sample or light sensor.
- The light sensor should be facing upwards.
- Don't move the leaf too much from it's natural position .
- Clamp the leaf on the left side if leaf direction is important to you.
- Make sure the leaf covers the whole measurement area, without any holes in the leaf.
- If there are holes, your signal quality will suffer and results will be poor.
- If your leaves are small, consider using a mask
- Since plants adapt to light conditions very quickly, take those measurements quickly.
- You are the first line of defense against poor data collection!
Understanding A Measurement
After you take a measurement, you will see lots of numbers, what do they all mean??
- The project everyone automatically joins uses a protocol called "Leaf Photosynthesis".
- The protocol collects the following parameters amongst others:
- Phi2 - Percentage of light energy captured by Photosystem II which is directed towards Photochemistry and makes ATP and NADPH and ultimately sugar for the plant to grow.
- PhiNPQ - Percentage of light energy captured by Photosystem II which is directed towards non photochemical quenching and is dissipated as heat inside the leaf.
- PhiNO - Percentage of light energy captured by Photosystem II which is directed... somewhere else.
- Relative Chlorophyll Content - Concentration of chlorophyll in the leaf.
- ECSt, vH+, and gH+ - Describes the accumulation of protons in the thylakoid and their flow through ATP synthase.
- Leaf Temperature Differential - Difference in temperature between the leaf and ambient air in degrees Celsius.
- PAR - Photosynthetically Active Radiation and that's the wavelengths of light from 400 to 700 nanometers.
- Leaf Angle - Angle of the leaf, relative to the ground. and ranges from 0 to 180 degrees.
Measurement Quality and Upload
To have a great project, you have to make sure you have great quality measurements!
- If we think a data point might have something wrong with it, you will receive a warning notification in the app.
- Out of range or too noisy measurements will yield a red danger of yellow warning notification.
- Blue notifications are for information only.
- Noise can come from the sample shaking wind, or a shaky hand.
- Try stabilizing your hand or leaf stem if you keep getting warnings.
- Problems can be due to leaf being injured or dead, and not your technique!
- You can keep dead leaf measurements if the project allows for it, otherwise discard it.
- In your measurement history, checked measurements have been uploaded to PhotosynQ.com. unmarked measurements are still only locally stored on your phone.
- Measurements can be auto uploaded, or uploaded all at once based on your in app settings.
- By not auto uploading, you can have a final quality check.