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I have found several somewhat related questions and answers here and elsewhere, but I couldn't find, if any scientist groups are researching genetical improvement possibilities of existing plants' photosynthesis processes to produce plants, which would be net oxygen producers and/or significantly increase their CO2 removal abilities.

For the most part, it seems people are preoccupied with getting energy out of plants, but if we allowed that potential energy to be used for photosynthesis, wouldn't such plants be useful even if we can't harvest energy from them?

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    $\begingroup$ Plants already do this on their own in the presence of high CO2. $\endgroup$
    – developerwjk
    Sep 26, 2017 at 19:55

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I'm not sure from your question if you're clear on the relationship between carbon fixation and 'energy', so just to be clear: carbon fixation in photosynthesis is the process of capturing CO2 and using it to store light energy in the form of carbohydrates. More CO2 capture = more harvestable 'energy'. Improving the efficiency of photosynthesis therefore captures more CO2 and generates more harvestable energy in the form of carbohydrates (edible or not).

There are three carbon fixation pathways in plants: C3, C4 and Crassulacean acid metabolism (CAM). The relative efficiency of the different pathways depends on the environment; for example, C4 plants are able to more efficiently fix carbon in drought, high temperatures, and limitations of nitrogen or CO2.

Because of this, scientists are indeed interested in engineering crop plants to use alternative carbon fixation pathways. One such project is the C4 Rice Project: http://c4rice.irri.org/.

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  • $\begingroup$ Thank you, this explains a lot. I was wondering if maybe there were plants who were not cultivated, but which were particularly effective at tying up CO2, but this shows the other implications. $\endgroup$
    – Gnudiff
    Sep 27, 2017 at 7:18
  • $\begingroup$ @Gnudiff no problem - glad it's useful! $\endgroup$
    – arboviral
    Sep 28, 2017 at 15:17
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Many if not most plants undergo less photosynthesis than they possibly could. This is because water availability is often their major limiting factor. Plants have to keep the tissue they respire through moist just like we do, so they are constantly losing water to the environment as long as they are taking in CO2. Because of this, many plants slow or limit their gas exchange and photosynthesis. Changing the efficiency of their photosynthesis will not have any effect on the plants ability to sequester carbon. Simple high efficiency irrigation might however.

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    $\begingroup$ I don't think OP is specifically asking about "Changing the efficiency of their photosynthesis"; I think his question applies equally to, say, genetically modifying a plant to be able to retain moisture better so that it will happily photosynthesize more (if that is indeed its limiting factor). $\endgroup$
    – ruakh
    Sep 26, 2017 at 23:37
  • $\begingroup$ its the same problem either way, biological gas exchange just forces you to lose moisture because it has to work through diffusion. plants have already done everything they can to limit it, including creating microclimates. $\endgroup$
    – John
    Sep 27, 2017 at 2:23
  • $\begingroup$ Thank you I upvoted this for indicating the issue being broader. $\endgroup$
    – Gnudiff
    Sep 27, 2017 at 7:20
  • $\begingroup$ It is very interesting you saying "plants have already done everything"... it would imply that there is no actual way to improve the process. However, plants don't have the same goals as us, when it comes to process usability. $\endgroup$
    – Gnudiff
    Sep 27, 2017 at 10:02
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    $\begingroup$ the lose of water is their major limiting factor meaning their is massive evolutionary pressure to do something about it. as long as gas exchange relies on diffusion, water lose will occur across the same membrane. $\endgroup$
    – John
    Sep 27, 2017 at 13:53

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