# What does potassium do?



## aquariums_101 (Aug 31, 2014)

What exactly does potassium do in a planted aquarium?


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## Zapins (Jul 28, 2004)

Potassium is used by plants for growth and to maintain the many cellular reactions that they need to stay alive. There are hundreds of enzymes and proteins that potassium is used in. Without enough potassium plants will die. It is one of the most common nutrient deficiencies that aquatic plants get. Plants need a lot of it to grow properly.

If you want to see some specific examples of where potassium is used in plants you have have a look through this document: https://www.ipni.net/ppiweb/bcrops.nsf/$webindex/84CBB51751971AB3852568F000673A10/$file/98-3p04.pdf


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## Yorkie (Sep 8, 2014)

Hi Folks,

I should be in bed by now but I was struck by the apparent difference between above ground plants and those of the submerged aquatic variety.

For terrestrial plants (is that the correct term?), I have always understood the following relationship:

Nitrogen (N) for leaf growth.

Phosphorus (P) for roots.

Potassium (K) for flowers/fruits.

Is there any correlation between the above relationship and what goes on in aquatic plants? I'm not trying to deviate from the OP's question - just add to it.

Y.


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## Zapins (Jul 28, 2004)

I am not sure where the advice on P for roots, K for flowers, etc comes from but I suspect if that advice is true it probably means that those tissues need more of those nutrients to do their job than other tissues. It does not mean that the other tissues in a plant don't use each of those nutrients.

Every cell in a plant whether it is flowers/fruit/roots/leaves/etc uses all of these nutrients (and each of the other essential plant nutrients). They do however differ in the amount of each nutrient they need per tissue.


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## Yorkie (Sep 8, 2014)

Zapins said:


> I am not sure where the advice on P for roots, K for flowers, etc comes from but I suspect if that advice is true it probably means that those tissues need more of those nutrients to do their job than other tissues. It does not mean that the other tissues in a plant don't use each of those nutrients.
> 
> Every cell in a plant whether it is flowers/fruit/roots/leaves/etc uses all of these nutrients (and each of the other essential plant nutrients). They do however differ in the amount of each nutrient they need per tissue.


Hi Zapins,

Thanks for the feedback.

As a keen gardener, I have repeatedly come across statements about the importance of each nutrient to a plant. Here is an example:

http://www.bbc.co.uk/gardening/basics/techniques/soil_feedingplants1.shtml

Y.


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## Zapins (Jul 28, 2004)

A good link. They summarize the general important details.

Macros: NPK (the 3 nutrients most used by plants)
Species variation: some plants need more of one nutrient or another. They mentioned tomatos and potassium. In aquariums hygrophilas need more potassium.

They do also mention that:


> To remain healthy, plants also need other nutrients, such as calcium (Ca), sulphur (S) and magnesium (Mg), as well as zinc (Zn), iron (Fe), copper (Cu), boron (B) and manganese (Mn). Smaller amounts of these will be contained in most general fertilisers.


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## Tugg (Jul 28, 2013)

I like North Carolina's site:
http://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htm


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