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#16
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Is Potassium not assimilated by plants ?
Elaine T wrote:
Philippe Lemaire (remove oldies) wrote: Your answer is mostly interseting although some words as cytosolic is not used every day ;-) "Cytosolic" means dissolved in the fluid on the inside of a cell. I was trying to respond to both you and Andrew at the same time. My main problem is to add Nitrates to keep the level at 30 ppm... As therfore I add too much Ca or Mg. K comes mainly from TMG and KH2PO4. If I increase waterchanges, I shall add still more nitrates :-( Why are you keeping nitrates at 30 ppm? That's part of your problem! Everything I've read suggests that 5-10 ppm nitates is preferable. Here's an article on recommended dosing levels. http://www.sfbaaps.com/articles/barr_02.html I don't even have problems with nitrates below 5 ppm as long as I'm dosing every couple of days. My GBA are quite calm since I moved from 15 to 30 ppm nitrates. Presently, I already put some nitrates everyday not have higher instantaneous values. Thanks for the help ! Are Ca and Mg cytosolic too ? Philippe |
#17
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Is Potassium not assimilated by plants ?
Andrew wrote:
Potassium is not integrated into the plant strucure to any great extent. Potassium is predominantly involved in ion channels. It regulates potential across the cell membrane, providing energy for cellular processes, maintaining osmotic pressure, etc. Take away potassium and the cell's biological processes shut down. FWIW plants actually have quite a high potassium demand, second only to nitrogen. Andrew Define integrated. By integrated into the plant structure I meant K is not usually covalently integrated into protein, lipid or carbohydrate structures as is the case for nutrients such as N and P. It remains in in a free state in the intracellular matrix. Remove a plant stalk, and you remove quite a bit of potassium from the closed tank system. While potassium is mostly cytosolic and not bound to protein, it is still intracellular (remember, high Na+ outside, high K+ inside). Of course, and if you scoop a bucket of water out of your tank you remove quite a bit of water from a closed system but it doesn't mean the water is integrated into the structure of the bucket. That means it is sequestered from the tank water and there is net uptake as plants grow. I never said it wasn't sequestered just not iintegrated into the "structure" of the plant. You do remove a lot of K when you prune, etc. I believe that is Philippe's essential question, since he is confused about the accumulating potassium in his aquarium. Semantics regarding what makes a structurally integrated component of a plant aside, I believe that question was answered before I posted, ie yes, K is taken up by the plant so his rising levels of K is unlikely to be due to the plant not using it, assuming he's not over supplying it (Given aquatic fertilizers are high in K and Phillipe hasn't said how much N and P are being supplied by the tank's bioload, this may be a possibility). Philippe asked a further question regarding what K does. This is what my post referred to. As for which nutrients leave a dead plant first, my best guess (for the reasons stated above) is K, followed by N and P. As a general rule, it is preferable to remove dead plant matter from an aquarium rather than leave it to rot. Plant will often try to retain nutrients where possible. A lot of the soluble components of dying leaves (eg ions, amino acids, nucleic acids etc) are transported to the growing areas. What's left in the dead leaf are usually the structural components which are contain more N and P than K. When the leaf rots the locked up N and P are released while the K most likely remains in the living plant. Andrew |
#18
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Is Potassium not assimilated by plants ?
Andrew wrote:
Andrew wrote: Potassium is not integrated into the plant strucure to any great extent. Potassium is predominantly involved in ion channels. It regulates potential across the cell membrane, providing energy for cellular processes, maintaining osmotic pressure, etc. Take away potassium and the cell's biological processes shut down. FWIW plants actually have quite a high potassium demand, second only to nitrogen. Andrew Define integrated. By integrated into the plant structure I meant K is not usually covalently integrated into protein, lipid or carbohydrate structures as is the case for nutrients such as N and P. It remains in in a free state in the intracellular matrix. Remove a plant stalk, and you remove quite a bit of potassium from the closed tank system. While potassium is mostly cytosolic and not bound to protein, it is still intracellular (remember, high Na+ outside, high K+ inside). Of course, and if you scoop a bucket of water out of your tank you remove quite a bit of water from a closed system but it doesn't mean the water is integrated into the structure of the bucket. That means it is sequestered from the tank water and there is net uptake as plants grow. I never said it wasn't sequestered just not iintegrated into the "structure" of the plant. You do remove a lot of K when you prune, etc. I believe that is Philippe's essential question, since he is confused about the accumulating potassium in his aquarium. Semantics regarding what makes a structurally integrated component of a plant aside, I believe that question was answered before I posted, ie yes, K is taken up by the plant so his rising levels of K is unlikely to be due to the plant not using it, assuming he's not over supplying it (Given aquatic fertilizers are high in K and Phillipe hasn't said how much N and P are being supplied by the tank's bioload, this may be a possibility). Philippe asked a further question regarding what K does. This is what my post referred to. As for which nutrients leave a dead plant first, my best guess (for the reasons stated above) is K, followed by N and P. As a general rule, it is preferable to remove dead plant matter from an aquarium rather than leave it to rot. Plant will often try to retain nutrients where possible. A lot of the soluble components of dying leaves (eg ions, amino acids, nucleic acids etc) are transported to the growing areas. What's left in the dead leaf are usually the structural components which are contain more N and P than K. When the leaf rots the locked up N and P are released while the K most likely remains in the living plant. Andrew Thanks for this precise answer ! So, I know now that pruning remove K but not removing old decaying leaves... Could you comment also on Ca and Mg ? I first thought it was related on which type of leaves (new/old) were affected by deficiencies... However, P, N and K affect old leaves making that not a good critrerion ! Philippe whose English cannot match yours |
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