biochemistry - Can plants suffer from CO2 poisoning?

Is there a point where too much CO₂ is bad for a plant? Basically when there is too much CO₂ in the air can a plant get sick?

Since plants photosynthesize and need CO₂ to generate glucose and store starch, and since chemical reactions are pushed toward their end product when the reagent concentrations are increased, one would expect that more CO₂ would be better, at least lead to increased growth and survival rates.

Is there a ceiling where CO₂ gets toxic?

Answer

Short answer
It has been shown that plants may already suffer from doubling the atmospheric CO₂ concentration from 340 to 610 ppm, something that might happen during the next hundred years or so based on current emissions.

Background
A popular science website tells us that an excess of carbon dioxide (CO₂) reduces the rate of transpiration of some plants. This is so because the stomata, which are the openings of the leaves (Mansfield & Majernik, 1970) and used for exchanging gases as well as water vapor (transpiration) will close when there is too much CO₂ in the air, or other polutants such as SO₂. As transpiration drops, the water flow from the soil to the leaves also drops, causing a runoff of water.This in turn stalls nutrient uptake. Indeed, doubling the present-day CO₂ concentration to 610 ppm does not necessarily lead to increased growth and may in fact inhibit growth due to excess starch formation in the leaves, indicating it's simply stored as backup energy, nothing else (Coviella & Trumble, 1999). It is believed that plants might be near their saturation point and cannot eliminate CO₂ faster than they are doing right now.

Somehow plants also become more susceptible to insect foraging when CO₂ concentration increases.

Note however, that CO₂ tolerances are species dependent. Most research in this arena has focused on common crops. CO₂ tolerance in for example cotton plants is low, and starch buildup has been observed in the entire plant, but especially in the root systems and the stem (Hendrix et al., 1994). Other species, such as wheat and rice are less prone to effects of elevated CO₂ (source: Nature).

<sub>References
- Coviella & Trumble, Conservation Biology (1999); 13(4): 700–12

- Hendrix et al., Agricult Forest Meteorol (18994); 70(1–4): 153-62
- Mansfield & Majernik, Environmental Pollution (1970); 1(2): 149-54</sub>

<sub>Source
- Earth untouched</sub>