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Will more CO2 increase plant growth?

  1. Jul 3, 2011 #1
    I have been thing about this, seems logical in a way, most reactions increase with concentration surface area, temperature and catalysts.

    Some of the factors are listed here:-


    They seem pretty similar to the one I put in the answers to my Chemistry A level (a level below degree level, but I went on to do electronics instead).

    You see some people say talking to plants improves them and I was wondering if this could be due to them breathing out more concentrated CO2, or maybe it is a load of rubbish, I don't know.

    I am growing some plants so I might start talking to some of them as an experiment!!

    Makes a change from talking on here lol :smile:

    Anyway this link says so:-


    I am not sure if that is peer reviewed, but anyway they were played music so I guess that's not the same.
    Last edited by a moderator: Apr 26, 2017
  2. jcsd
  3. Jul 4, 2011 #2


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    As with the plant temperature thread some time ago the answer to this question is going to be that there are many factors affecting plant growth. The bottom link you provided isn't peer reviewed (you can tell because it's from a news paper :wink:) but here's two peer-reviewed papers on the subject

    Effects of atmospheric CO2 enrichment on plant growth: the interactive role of air temperature
    S. B. Idso1, B. A. Kimball1, M. G. Anderson2 and J. R. Mauney3

    Interactions between increasing CO2 concentration and temperature on plant growth
    J. I. L. MORISON1, D. W. LAWLOR2

    The first is just an abstract, but both indicate that whilst in general an increase in [CO2] can result in increased plant growth (sometimes in speed rather than overall size) there are differences between different species and the whole process of growth is affected by a multitude of interacting factors.
  4. Jul 4, 2011 #3
    An increase in atmospheric CO2 concentration upto 0.05% from the usual 0.03% can result in increased CO2 fixation rates but beyond this levels can be damaging for extended periods of time.

    In addition C3 and C4 plants respond differently to CO2 concentrations. C4 plants reach saturation at 360 μlL-1 while C3 plants do so at 450 μlL-1. So C3 plants respond better to increased CO2 concentrations in form increased productivity and this is used in the carbon dioxide enriched greenhouses with plants like tomatoes and bell peppers.
  5. Jul 4, 2011 #4
    Well obviously there are other factors involved, but it is good that we can increase the food supply by making use of the extra CO2. Faster growth would also be beneficial and could lead to an increase in the food supply for example by planting more than one crop in the season in instances where that was previously not viable.

    I guess one could quote Darwin and say survival of the fittest and his theory suggests that those plants which respond best to CO2 and grow better quicker stronger and faster and more nutrious will replace those plants which are not up to the mark of feeding the population.

    The bottom link does not really matter as playing music or sound to plants does not affect the CO2 levels in the air.
    Talking to plants would increase the CO2, so it seems a pity they failed to mimic the effects of talking to plants and instead just
    played music.

    I don't think anyone in their right minds would expect playing music to plants to affect their growth, but you never know, stranger things have happened!!
    Last edited: Jul 4, 2011
  6. Jul 4, 2011 #5
    There is a whole chapter dedicated to this question in

    The Emerald Planet by David Beerling - Oxford University Press.

    The results are quite suprising, but the book is readily accessible to an A level student and may be obtained from a good library.

    go well
  7. Jul 4, 2011 #6
  8. Jul 4, 2011 #7
    Why would anyone bother to write anything if it was all given away free online?

    I would put much more faith in the researched and peer reviewed information in the book. The author is the Professor of paleontology at the University of Sheffield.

    As I said the results (the response of plants to high and low carbon dioxidelevels) are quite suprising.
  9. Jul 4, 2011 #8
    It is hardly rocket science is it?
    There must be plenty of information available freely so why quote a restricted document?

    Professors write stuff as part of their work and get paid for it.

    I get a lot of scientific information rammed down my throat my the media for free so why not this?

    I mean it is a bit rich isn't it, with all the incredible amounts of info on the internet someone references a book!!
    You could not make it up!!!
    Last edited: Jul 4, 2011
  10. Jul 4, 2011 #9
    Ad hominem posts will not gain you many friends.
  11. Jul 4, 2011 #10
    Interesting article here


    With respect to CO2 utilization, plants are divided into two types: C3 plants and C4 plants. These names essentially distinguish two types of photosyntensis. C3 photosynthesis (so called because the photosynthetic process yields 3-carbon derivatives) has a problem in that sometimes O2 fills the role that CO2 is supposed to fill. When it does, much of the energy that goes into photosynthesis is wasted. C4 plants, on the other hand, starts with a gate, of sorts, that keeps much of the O2 out, so this waste happens less often.

    Most plants, including plants used in agriculture, are C3 plants. This includes lemon trees (virtually all trees, in fact), sugar beets, and potatoes. Corn and surgarcane are C4 plants.

    Each type of plant reacts to a change in CO2 concentrations differently. C4 plants already use CO2 efficiently. An increase in the concentration does not help them much. C3 plants, on the other hand, benefit greatly from increases in CO2 because less of the inefficient O2 photosynthesis occurs. Plants in a high CO2 environment increase their plant mass by 20 to 25%. Yields of some crops can be increased by up to 33%. This is the effect of doubling CO2 concentrations over Earth normal. Still higher concentrations can be expected to yield still better results.

    Note, however, that the effects vary even among different types of C3 plants. Some are better able to take advantage of higher CO2 concentrations than others, and a few actually suffer if CO2 concentrations are raised.

    But, there's a catch. These benefits occur only if the nutrient levels and the amount of water available also increase. CO2 alone does very little good. Consequently, to take advantage of a higher CO2 concentration, we must supply more water and bring in more nutrients (such as nitrogen).

    In fact, there is more than one catch. As a plant's production of starch from CO2 increases, it seems to reach some sort of saturation point. It reaches a point where it can no longer take advantage of the greater abundance of CO2. Scientists suspect that this is because there is a bottleneck in the plant's metabolic system. It can manufacture more starch, but it can't get it to where it is needed - or it can't use what it is getting. At this point, you might as well bring the CO2 concentration back down to normal levels for all the good you're doing. Or, if this point is close to the plant's maturation point, you can harvest it and plant the next crop.

    [Note: high conentrations of CO2 allows the plant to use water more efficiently. This is because the passageways that allow CO2 into the plant also let H2O out. Under higher CO2 concentrations, these passageways can be kept more tightly constricted, allowing less H2O to escape. But there is a tradeoff here between CO2 fertilization and efficient use of water. To the degree you have one, you must give up the other.]


    Fakhri A. Bazzaz and Eric D. Fajer, "Plant Life in a CO2-Rich World," SCIENTIFIC AMERICAN, January, 1992, pp 68-74.

    So there you have it most plants would benefit from higher CO2.

    OK there are a few other 'problems' however to me they are not real problems, ie that bit about needing more nitrogen, if you grow more food you will need more nitrogen anyway

    I found this interesting

    "Most plants, including plants used in agriculture, are C3 plants. This includes lemon trees (virtually all trees, in fact), sugar beets, and potatoes. Corn and surgarcane are C4 plants."

    It is just interesting that the C4 plants are the ones I know are used in biofuel, I guess that is not such a surprise as they 'eat CO2' better, and don't seem to benefit from higher concentrations because they already have as much as they can handle.

    Interesting stuff, I am growing some tomatoes and I am thinking about pumping CO2 into the greenhouse to increase the food yield produced.

    I am not to sure where to get the extra CO2 from though, is is cheap to buy?

    I guess big tanks of pressurised CO2 might be dangerous if they exploded. :bugeye:
    Last edited by a moderator: Apr 26, 2017
  12. Jul 4, 2011 #11
    Could you explain what Ad hominem means?

    I dropped Latin at the earliest opportunity thinking it was a dead language.

    Anyway i looked it up and still don't understand what you are talking about.

    Can you be more specific?
  13. Jul 4, 2011 #12
    Insulting the messenger, instead of listening to the message.

    It has been established that plants respond to increasing carbon dioxide levels first by decreasing underleaf stomata then by growing dissected leaves and then by reducing leaf size and finally by reducing leaves to spikes.

    (Ian Woodward, Nature 1987)
  14. Jul 4, 2011 #13
    Can you be specific and quote the alleged insult, I don't recall one.

    Furthermore the I don't see what point you are trying to make when you say:-

    "It has been established that plants respond to increasing carbon dioxide levels first by decreasing underleaf stomata then by growing dissected leaves and then by reducing leaf size and finally by reducing leaves to spikes."

    So what is your point there? What are you trying to say?
    Did I ever say "that plants not respond to increasing carbon dioxide levels first by decreasing underleaf stomata then by growing dissected leaves and then by reducing leaf size and finally by reducing leaves to spikes."

    And what specifically is your point? You seem to expect me to guess what you are trying to say and I can't because I have no idea what you are on about.

    Can you be clearer.

    You seem to have a talent for being unclear in what you are saying.
  15. Jul 4, 2011 #14
    What he's saying in a very general sense that with an abundance of CO2, it no longer becomes a limiting factor in plant growth. As a consequence, some plants will evolve fewer stomata on the leaves because the increase in CO2 allows for it. They are, perhaps, 'fine-tuned' to the current concetration and would not use more if it were available, opting for fewer stomata.

    In other words, if you were really thirsty but could only fill your glass half full, you might want two or three glasses to quench your thirst. But if you could fill your glass to the top, maybe just one glass would be enough. After all, there is only a certain amount of water your body can process in a day.

    The interesting thing about this phenomenon is that not only does it occur, but it has also resulted in less water being cycled from the plant to the atmosphere via transpiration (which occurs through stomata). That water instead gets flushed out of the system through lakes and rivers leading to increased run-off, which can be a problem for flood-prone areas.

    I am not suggesting we are in a mass extinction event, but such a change in run-off patterns is well-documented across the Permian-Triassic extinction event.
  16. Jul 4, 2011 #15
    First off I did not specify an abundance of CO2 to to restrict the answer to that is inappropriate.
    Fact is that for most plants there is no an abundance of CO2, so to put that restriction is inappropriate.

    I will look into the water problems claims.
  17. Jul 4, 2011 #16
    No need to get defensive; inherent to any hypothetical scenario of increased CO2 is how that may or may not be a controlling factor on plant growth and evolution. Second, placing a 'restriction' on a type of plant that behaves in the manner described is certainly appropriate; it goes without saying that such controls are not applicable to plants that do not behave that way.
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