1. Joined
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    19 Sep '14 10:018 edits
    some progress has been made in research into improving photosynthesis in plants by genetically engineering some to photosynthesize more like cyanobacterial by using one of their enzymes

    http://phys.org/news/2014-09-efficient-photosynthesis.html

    Of course, the irrational paranoid anti-GM people will fiercely oppose this tooth and claw regardless of how much it could potentially deduce world hunger and reduce the risk of famine when applied to common food crops.
    Hopefully they will fail to stop this so many of the worlds poorest at least have a chance to benefit and suffer just a little less from hunger (I am not implying here that low crop yield is the main cause of would hunger. I understand perfectly that politics is the main cause. But, nevertheless, with all else being equal, the higher the food crop yields, the better )
  2. Cape Town
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    19 Sep '14 12:09
    Originally posted by humy
    Of course, the irrational paranoid anti-GM people will fiercely oppose this tooth and claw regardless of how much it could potentially deduce world hunger and reduce the risk of famine when applied to common food crops.
    The article keeps talking about 'yields'. If a plant has more efficient photosynthesis, does it grow faster? Larger?

    Funny how the crop they are working with is tobacco.

    (I am not implying here that low crop yield is the main cause of would hunger. I understand perfectly that politics is the main cause. But, nevertheless, with all else being equal, the higher the food crop yields, the better )
    Its complicated. In Zambia, the main food crop is grown in a constant boom bust cycle. One year there is oversupply so the price drops and fewer farmers plant. The next year the price is high, and more farmers plant etc. Poor government policy tends to make this even worse.
    For the individual farmer, higher yields for a given amount of land, fertilizer and labor is certainly a good thing. But presumably higher yields for one farmer means loss of business for another. If those higher yields come first to the commercial farmers, it may even spell disaster for the poor.
    Also badly needed is education (in agriculture) as there are already tried and tested ways to double the yield for most farmers in Zambia.
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    19 Sep '14 13:41
    Originally posted by humy
    Of course, the irrational paranoid anti-GM people will fiercely oppose this tooth and claw regardless of how much it could potentially deduce world hunger and reduce the risk of famine when applied to common food crops.
    Is this thread about photosynthesis *or* is it a political statement about anti-GM people?

    If it's about photosynthesis, then this thread belongs to Science Forum.
    If it's about GM-debate, the it should be moved into the Debate Forum and stay there.
  4. Joined
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    19 Sep '14 13:59
    Originally posted by FabianFnas
    Is this thread about photosynthesis *or* is it a political statement about anti-GM people?

    If it's about photosynthesis, then this thread belongs to Science Forum.
    If it's about GM-debate, the it should be moved into the Debate Forum and stay there.
    Its about both but point taken and you are right:
    I should have made that two posts; the science part for here and the political part in the debates forum.
  5. Joined
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    19 Sep '14 14:275 edits
    Originally posted by twhitehead
    The article keeps talking about 'yields'. If a plant has more efficient photosynthesis, does it grow faster? Larger?

    Funny how the crop they are working with is tobacco.

    [b](I am not implying here that low crop yield is the main cause of would hunger. I understand perfectly that politics is the main cause. But, nevertheless, with all else being equa ...[text shortened]... ture) as there are already tried and tested ways to double the yield for most farmers in Zambia.
    The article keeps talking about 'yields'. If a plant has more efficient photosynthesis, does it grow faster? Larger?

    yes, generally both but especially faster. I should know because I am a semi-expert on that for I studied this intensively with formal education.
    Funny how the crop they are working with is tobacco.

    That is because tobacco plants are very often if not usually the first-plant-of-choice for many generic experiments by geneticists because more is known about how to fast and efficiently generically manipulate tobacco plants than most other plants. This is why geneticists often try out a genetic manipulation on tobacco plants first before they attempt to them move on onto whatever is the kind of plant they really want to generically manipulate because that way they can check their hypotheses with the least amount of time and cost before spending much more time and cost on generically manipulating a much harder plant to genetically manipulate with the risk of then only getting a disappointing result.

    This is why there has been some serious consideration of genetically engineering specifically tobacco plants as opposed to some other kind of plant for producing not tobacco products but producing such things as biofuels and medicine! (for evidence of this, see: http://www.geneticliteracyproject.org/2013/10/29/genetic-modification-may-help-tobacco-find-new-life-as-health-savior-and-biofuels-source/ ) It isn't because tobacco plants are particularly efficient at producing none tobacco products, they are not, but rather because they are currently simply so much easier and quicker to genetically modify to produce such none tobacco products. If you used some other type of plant, currently, the costs of making that work would probably be much higher and I presume probably take extra months or perhaps even years of research to make it happen.

    So, the reason why they first do it with tobacco plants is very unlikely to be because their primary goal is to increase the yield of tobacco if that is what you were thinking?
  6. Cape Town
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    19 Sep '14 17:04
    Originally posted by humy
    So, the reason why they first do it with tobacco plants is very unlikely to be because their primary goal is to increase the yield of tobacco if that is what you were thinking?
    I actually knew that tobacco was popular for genetic experiments. I just thought it was funny that they were on the one hand talking about solving world hunger and on the other, working with tobacco, a plant responsible for possibly as meany deaths as hunger.
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    19 Sep '14 18:114 edits
    Originally posted by twhitehead
    I actually knew that tobacco was popular for genetic experiments. I just thought it was funny that they were on the one hand talking about solving world hunger and on the other, working with tobacco, a plant responsible for possibly as meany deaths as hunger.
    oh right -sorry about that! When you said "funny", I didn't think you meant "funny" as in ironic but "funny" as in suspicious. I thought you were being cynical. My apologies.

    I cannot help feel that it is a pity that tobacco plants just happen to be currently the easiest plants to genetically manipulate. I would (and I assume most other people would ) much prefer it if it was something totally none noxious and not associated with death or suffering such as cabbage or dandelion or whatever.
    The ideal plant for this would be one that is small and can have many generations a year. For this reason, I think there should be research into finding ways of making it easier, cheaper and quicker to genetically manipulate something like land cress and do it with at least as much ease as currently with tobacco so that we can abandon using tobacco.
  8. Standard memberDeepThought
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    19 Sep '14 19:07
    Originally posted by twhitehead
    The article keeps talking about 'yields'. If a plant has more efficient photosynthesis, does it grow faster? Larger?

    Funny how the crop they are working with is tobacco.

    [b](I am not implying here that low crop yield is the main cause of would hunger. I understand perfectly that politics is the main cause. But, nevertheless, with all else being equa ...[text shortened]... ture) as there are already tried and tested ways to double the yield for most farmers in Zambia.
    It's about energy. The more a plant can photosynthesise the more energy it has available for growth and so forth.
  9. Cape Town
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    20 Sep '14 06:50
    Originally posted by DeepThought
    It's about energy. The more a plant can photosynthesise the more energy it has available for growth and so forth.
    Yes, but does it actually translate into faster growth. With animals, extra energy can result in faster growth to a degree, but quite often it just leads to obesity. I was wondering whether plants are limited by chlorophyll efficiency, or whether there might be other factors such as nutrients, CO2 uptake etc.
    Having broad leaves to collect sunlight is obviously one way to improve efficiency of sunlight collection, but many plants seem to get by without doing that. Although they tend to be slower growers as a result, maybe there are benefits to slower growth.
  10. Standard memberDeepThought
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    20 Sep '14 17:25
    Originally posted by twhitehead
    Yes, but does it actually translate into faster growth. With animals, extra energy can result in faster growth to a degree, but quite often it just leads to obesity. I was wondering whether plants are limited by chlorophyll efficiency, or whether there might be other factors such as nutrients, CO2 uptake etc.
    Having broad leaves to collect sunlight is ob ...[text shortened]... Although they tend to be slower growers as a result, maybe there are benefits to slower growth.
    Carbon dioxide and water uptake are fundamental limitations on photosynthesis, it's not just sunlight. Yes, I think you are right and there are other limitations, such as nitrogen, but energy is fundamental. I think that plants tend to grow if they can, they don't get fat in the way animals do. Alternatively they might go into their reproductive cycle earlier. Of course, we are talking about an entire kingdom in the tree of life, so it's probably a mistake to make general statements.
  11. Joined
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    20 Sep '14 20:525 edits
    Originally posted by twhitehead
    Yes, but does it actually translate into faster growth. With animals, extra energy can result in faster growth to a degree, but quite often it just leads to obesity. I was wondering whether plants are limited by chlorophyll efficiency, or whether there might be other factors such as nutrients, CO2 uptake etc.
    Having broad leaves to collect sunlight is ob ...[text shortened]... Although they tend to be slower growers as a result, maybe there are benefits to slower growth.
    greater amount of photosynthesis generally does result in greater growth and this is why greenhouses air is often artificially enriched by CO2 -the CO2 increases the rate of photosynthesis and this increases the rate of plant growth and that also translates into higher yields. So, logically, assuming no surprising adverse side effects from whatever particular genetic engineering is used (unlikely I think but possible ) , increasing the energy efficiency (by GM ) of photosynthesis should generally have the same effect. I would be completely astonished if it didn't!
  12. Subscribersonhouse
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    21 Sep '14 01:08
    Originally posted by humy
    greater amount of photosynthesis generally does result in greater growth and this is why greenhouses air is often artificially enriched by CO2 -the CO2 increases the rate of photosynthesis and this increases the rate of plant growth and that also translates into higher yields. So, logically, assuming no surprising adverse side effects from whatever particular g ...[text shortened]... osynthesis should generally have the same effect. I would be completely astonished if it didn't!
    Wonder if there is a connection between CO2 sequestering in the form up more uptake by plants tending to lower the atmospheric levels? Plants must love the increase in atmospheric CO2.
  13. Cape Town
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    21 Sep '14 12:37
    Originally posted by humy
    greater amount of photosynthesis generally does result in greater growth and this is why greenhouses air is often artificially enriched by CO2 -the CO2 increases the rate of photosynthesis and this increases the rate of plant growth and that also translates into higher yields.
    Surely that suggests CO2 is a limiting factor?
  14. Standard memberDeepThought
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    21 Sep '14 15:51
    Originally posted by twhitehead
    Surely that suggests CO2 is a limiting factor?
    Not the way we are pumping it into the atmosphere.
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    21 Sep '14 18:3211 edits
    Originally posted by twhitehead
    Surely that suggests CO2 is a limiting factor?
    yes, it is a significant limiting factor at least usually during when there is direct sunlight and the temperature is very roughly in about the right range for optimum efficiency of photosynthesis.

    This is because those conditions produce what is called a high "carbon dioxide gradient" that has the effect of greatly reducing efficiency of photosynthesis (weirdly, I have so far failed to find a link to this even though it is extremely common knowledge amongst biologists! ) . Basically, what happens is that the cells in the leafs photosynthesis so fast that they use up CO2 so fast deep in the leaf tissue that the diffusion of CO2 into the leaf from outside the leaf cannot keep up and this results in a sharp drop of CO2 concentration deep in the leaf hence a significant CO2 concentration gradient forms from outside the leaf to inside the leaf. This sharp drop of CO2 in the leaf means there isn't enough CO2 there for the maximum possible rate of photosynthesis given the amount of light and given the temperature than if, hypothetically, there was the same concentration of CO2 there as outside the leaf. The result is that more of the light energy absorbed by the cells is wasted before it can be used to fix the carbon from CO2.

    But, at reasonable temperatures, when there isn't nearly so much sunlight i.e there is relatively dim light, then increasing CO2 would generally only increase photosynthesis a very tiny bit and thus make some but very little difference because then the amount of sunlight becomes the dominant limiting factor, not CO2. Similarly, if the temperature is too low (and sometimes if it is too high but usually it is how low it is that really counts unless you are talking about it being so high as to begin to harm the plants ) this slows down photosynthesis (because most chemical reactions are slowed by lower temperatures ) and then temperature becomes the dominant limiting factor.

    note that there are several other important common limiting factors not mentioned above, such as luck of water or some other physiological stress or disease attack etc, that very often also has a significant impact on the efficiency of photosynthesis.

    ( I have studied all of this pretty intensely so I know exactly what I am talking about here )
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