Stomata - Opening and closing times

[rbarata]

My doubt is:

If a CAM plant is in the dark and I change it into light how much will it take for the stomata to close. And the reverse, from light to dark (opening).

Thank you

[Ray]

I cannot answer your question, but stomatal opening and closing is controlled by light levels, humidity and the availability of water at the root system...

[rbarata]

I'm aware that it might be a difficult question...I always assumed without any objective evidence to support it that it might take some time (1 hr, at least).
I water many of my orchids at night (rupics, Catts, etc) but, obviously, I need light to do it. So, there's a darkness interruption for a few minutes.
Hence my question....

[Louis_W]

I don't have any real facts on this but my guess is that the opening and closing of stomata is triggered by multiple cues at the same time. I believe that they can open in cooler times of day or more humid periods. It's difficult to get to the bottom of this question because many orchids can flex between C3 and CAM, and they don't seem to be very clear on what the deal with that is.

Approaching from the practical rather than the microbiological side of things may be more clear. Many of us grow in urban environments with plenty of light pollution and here doesn't seem to be too much problem. That not to say things couldn't be improved with darker nights. I have heard that C. walkeriana and perhaps C nobilior are pretty sensitive to night time illumination. That could be why but I'm not sure.

[estación seca]

I don't know about orchids. Desert cacti, obligate CAM plants opening stomata only at night, can take up water at any time, even with stomata closed. The interior of the plant has a much higher concentration of solutes than the exterior, so transpiration is not needed for water uptake. I would be surprised if CAM orchids were different.

[rbarata]

I've read a study about this subject a few months ago. The object were two different CAM orchid species (can't remember where I have found it neither which species) and the time needed for the stomata to close/open had a huge variation. One of the species needed less than a minute while the other needed a few hrs.

[isurus79]

Originally Posted by Louis_W

I have heard that C. walkeriana and perhaps C nobilior are pretty sensitive to night time illumination.

Nobilior are not sensitive to night light at all

---------- Post added at 12:03 PM ---------- Previous post was at 11:59 AM ----------

Well, plants use their circadian rhythm to anticipate sunrise (see link below), so it would make sense that CAM plants (and others) can anticipate sunset. Anecdotally, walkeriana starts its fragrance just before the sun is up, also indicating some anticipation of sunrise.

Sunflowers Use Internal Circadian Clock to Follow Sun | Sci-News.com