Hi Fiamma,

you are correct, for a regular measurement of NPQ you would require a dark adaptation. The RIDES protocols are meant for fast measurements in the field and a dark adaptation would slow this process down. So instead NPQ, NPQt is calculated, since it doesn't require a dark adaptation. The key is, that a value for the maximum quantum efficiency in a range of plants of about 0.83 is assumed. Here is a link to the publication.

Please find a list of the most common parameters and the way they are calculated here in the Documentation. The corresponding papers are referenced there as well.

~Sebastian

Hi Fiamma,

I would like to add to Sebastian’s comment. The noisy signals of ECSt and P700 are often caused by the vibrations. It is sometimes hard to hold the instrument steady in the field, especially on a windy day. I usually steady the hand holding MultispeQ with the other hand, or a nearby fence or monopod/tripod. When you are measuring a long leaf that flatters in the wind, that also causes a noisy measurement. You could hold on to the end of the leaf as long as you do not disturb the leaf angle.

Also, the ECSt signal can become noisy if the background light is very low such as 20 micro mol/s/m2. I hope this helps.

-Atsuko

Dear Sebastian and Atsuko, Thank you a lot for the links and the answer! Somehow I've missed the NPQ(T) paper, now it's much more clear!

And thank you also for the reference of the parameters and the hints on handling the multispeq!

I have also another question, handling the multispeq we have realized that sometimes the recorded temperature seem way off the actual environmental temperature... that's quite strange, is it possible that if you hold it too thigh you are actually warming up the temperature detector? It's really strange as the detector is located on the tip of the clamp (that's how I understand it at least) from the help page.

Have you ever encountered a similar issue?

Hi Fiamma,

Before taking the MultispeQ to the field, please check where it was stored. As you can see, when the temperature in the field is different from the inside of the building or a car, you need to wait for the instrument to be warmed or cooled to the outside temperature. I usually place the MultispeQ outside for a while until it adjusts to the field condition. -Atsuko

The disruptive signals observed in ECSt and P700 readings often stem from vibrations, a common challenge, particularly in field settings on windy days. To mitigate this, I typically stabilize the MultispeQ by supporting the hand holding it with my other hand, or by utilizing a nearby fence, monopod, or tripod. When measuring a lengthy leaf affected by wind-induced fluttering, noise in the measurement may arise. In such cases, holding onto the leaf's enter link description hereis viable, as long as it doesn't interfere with the leaf angle. Additionally, note that ECSt signals might exhibit noise in low background light conditions, such as 20 micro mol/s/m2. Trust this proves beneficial.