Quote:
Originally Posted by Edward
Not exactly true because K is a mobile element. Plants do take more of K then they actually need so assuming a deficiency from testing K excess is probably misleading.
|
I agree that K is a mobile element in the fact that it is not incorporated into the structure of the plant and is constantly being exchanged for other K outside the plant. But from my understanding of cellular biology it doesn’t seem possible for a plant to take in more K than it needs.
Cellular levels of K must be in a very narrow range for cells to function properly. Plants have biochemical mechanisms that “pump in” and “pump out” K. They can concentrate K from the environment using “pumping in” mechanisms. As the level of cellular K increases, the “pumping out” mechanism starts up. Eventually, the “pumping in” and “pumping out” mechanisms are in balance and the level of K remains constant in the cell.
As long as the plant volume is constant, the level of K in the plants and aquarium water will be the same. As plant volume increases, more K is required and is removed from the tank water.
It may be that my plants have been suffering from a long term deficiency and the amount of K being taken up is just bringing the cellular level back to normal. If that is true then K consumption will eventually decline. I’m interested to see what happens.
BTW. My notion that growth is limited by available K is not unique. There are a large number of aquatic plant fertilizers on the market that supply only K, Fe and trace elements.
Potassium test results
Re: Potassium test results
Linear Mode
