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What does the plant look like when P-limited and really too low light ?

Discussion in 'General Plant Topics' started by a-hua, May 19, 2011.

  1. a-hua

    a-hua Subscriber

    Aug 5, 2007
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    2:58 PM
    hi all

    If the others(co2, N, trace,...) are not limited, what does the plant look like when P-limite and too low light?

    I just know P-limited can cause GSA....on leaf and glass(woods, rocks...)....what makes the difference ?

  2. dutchy

    dutchy Plant Guru Team
    Lifetime Member

    Jul 6, 2009
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    P limiting can cause some mild stunting while too low light can cause loss of colour, stretching and dwarf leaves, so there's a clear difference. P limiting does not show very much, sometimes not even at all, it depends of the plant species involved.
    #2 dutchy, May 19, 2011
    Last edited by a moderator: May 19, 2011
  3. Tom Barr

    Tom Barr Founder
    Staff Member Administrator

    Jan 23, 2005
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    Well, limitation can be mild, moderate or severe, it's not on/off type of thing.

    We often use language this way........but it's more a gradation over a wide range.
    Each species will respond differently as well.
    The temporal effects also play a large role in the limitation and when it occurs in the life history, storage ability of various structures the plant has etc.

    Too low of light needs to factor everything else as non limiting to test this.

    So CO2 needed added if you want to address too low of light in most test.
    If you want to know under a co limitation of light and CO2.........then this can be done as well.

    I do not know the absolute values for light, but generally 30 micmols seems to be about the limit for decent general growth over the bottom of an aquarium for perhaps 90-95% of plant species.
    Going down to the LCP is going to be tougher, so some buffer room about the LCP for various species differences etc will be required, otherwise, you need to be very specific about the tank and the species of interest.

    Same for PO4 pretty much.

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