CO2 generation

[littlefrog]

I think to kill two hobbies with one stone, brew beer... The CO2 from fermentation would help your orchids grow better. Plus you get it over a period of several weeks, rather than all at once.

[tropterrarium]

Originally Posted by AHAB

Is there a list of orchids that are CAM?

See this thread:
Are orchids C3, C4, or CAM plants?

There's a link to a very nice paper:
Crassulacean Acid Metabolism and Epiphytism Linked to Adaptive Radiations in the Orchidaceae -- Silvera et al. 149 (4): 1838 -- PLANT PHYSIOLOGY

Molecular phylogeny of >1000 species across the board, with mapping of CAM vs C3. Too bad, the phylogenies only go to genus, not species. I think anyone can read the paper and get the main points. But there is some moderate statistics and some phylogenetics lingo in there. Reader beware.

[Ray]

The atmosphere is typically in range of 300-400 ppm CO2. From what I've read, the optimal "boost" occurs at about 3000 ppm, but higher than that is toxic to plants and you.

I ran all last winter at 3000 ppm in my greenhouse (can't do it in the summer due to venting), and saw no improvement.

[AHAB]

Ray,
I remember reading that 1,300 PPM was optimal for ornimental type crops and too much could be actually harmful to the crops.
Did you run the CO2 day and night?
Often they need day or night without additional CO2 to assimilate the absorbed CO2 and convert it into sugars, there is a four stage cycle they go through each day.
Are you sure you ran it that high? Did you use a CO2 meter/doser?
Thanks for your info
Jim

[Ray]

You're right - I remembered wrong. The recommended rate (and where I ran it) was 1500 ppm, and I only maintained the level in the daytime.

[AHAB]

Thank goodness!
I humbly suggest using it at nighttime if you try it again. If I remember right, CAM plants open up their stomata at night when the humidity is relatively high and also absorbs CO2 at the same time.
Of course it all depends on what you are growing also.
Perhaps during the warmer months it would be more beneficial, since growth is at it's peak, CO2 would give it more of a noticeable boost.
Since most of the dry mass of the plant is carbon I would think that adding CO2 would contribute to the amount of carbon the plant would be able to assimilate into tissue.
I've been really wanting to use CO2 in my greenhouse but have yet to find many people who have used it for orchids, ornamental crops definitely, they do spend a great deal on co2 systems because it works for those crops.
Terry Root of OZ (Orchid Zone) mentioned at a conference that he is downwind from an energy plant and that his atmospheric co2 levels are 3x normal levels. He said it did make a difference for his crops...

[harleymc]

Increased CO2 in the atmosphere will acidify the nutrient bearing solution around the roots. This will make some nutrients less bio-available (and some more so).
So, it is not clear that increasing CO2 concentration would necessarily increase plant groth rates without changeing feeding to compensate.

[Mercaptan]

Originally Posted by harleymc

Increased CO2 in the atmosphere will acidify the nutrient bearing solution around the roots. This will make some nutrients less bio-available (and some more so).
So, it is not clear that increasing CO2 concentration would necessarily increase plant groth rates without changeing feeding to compensate.

Only with osmosed water. The blood's pH is around 7.40, with 40 to 46 mmHg pCO2. The solution is to dilute with some fertilizer to buffer.