'What Orchids Eat', importance of calcium

[Ray]

King - no doubt there is a need for all of the mineral elements in probably every plant, HOWEVER - just because one type needs a lot of something has absolutely no bearing on whether another does.

If I was to use that logic, I could point to mangroves and assert that all plants should be exposed to lots of sodium chloride.

Plants that are indigenous to one environment will have evolved to cope with whatever is available. If those are shifted to a different environment offering different supplies, they may-, or may not do well.

I imagine that exposure to something in excess of what the creature has evolved to "need" or "tolerate" is not healthy.

The hypothesis surrounding K-Lite is that most orchids have evolved to survive in a very potassium-deficient environment, not a potassium-free one, so we are trying to mimic that.

Even people have issues with excess potassium - hyperkalemia - which might lead to symptoms of fatigue, weakness, tingling, numbness, or other unusual sensations, paralysis, or difficulty breathing. I imagine there are ethnic groups that have higher overall potassium levels than others, but again, that doesn't mean that all of us should be exposed to the same levels. Heck, there was a study done at U of MD that showed a difference between how caucasians and African-Americans deal with potassium, and its relation to hypertension right here in the US.

[DavidCampen]

Originally Posted by Ray

King - no doubt there is a need for all of the mineral elements in probably every plant, HOWEVER - just because one type needs a lot of something has absolutely no bearing on whether another does.

If I was to use that logic, I could point to mangroves and assert that all plants should be exposed to lots of sodium chloride.

Yet the only evidence you have for this potassium toxicity thesis is the fact that potassium is toxic to fresh water mussels but whenever someone presents experiments done on plants that refute this potassium toxicity thesis you discount it because it was "not orchids".

When we were discussing this here last year I presented lots of experiments with plants that show the importance of potassium at concentrations equal to that of nitrogen but you discount everything because they were "not orchids".

Originally Posted by Ray

The hypothesis surrounding K-Lite is that most orchids have evolved to survive in a very potassium-deficient environment, not a potassium-free one, so we are trying to mimic that.

Orchids do not grow "in a very potassium deficient environment". K-lite does not mimic the environment that orchids grow in.

Originally Posted by Ray

Even people have issues with excess potassium - hyperkalemia - which might lead to symptoms of fatigue, weakness, tingling, numbness, or other unusual sensations, paralysis, or difficulty breathing. I imagine there are ethnic groups that have higher overall potassium levels than others, but again, that doesn't mean that all of us should be exposed to the same levels. Heck, there was a study done at U of MD that showed a difference between how caucasians and African-Americans deal with potassium, and its relation to hypertension right here in the US.

And this has nothing to do with plants.

Originally Posted by Ray

just because one type needs a lot of something has absolutely no bearing on whether another does.

Yet the best evidence in support of the potassium toxicity thesis is that potassium is toxic to freshwater mussels.

[King_of_orchid_growing:)]

While I do subscribe to the idea that different plants will have varying degrees of tolerance and uptake of certain nutrients. I cannot find evidence that supports K+ toxicity in plants. All I've ever found was evidence that supports that K+ is present in fairly high quantities in plants in general.

In fact, if you want to talk solely about orchids, in terrestrial orchids such as many species of Disa, there is indirect evidence that points to the fact that they may be K+ hogs. And by indirect evidence, I mean, the evidence had to be dug out not by researching the orchids themselves, but by researching the soils they grew in in the wild. They may grow in nitrogen poor environments, but K+ is very abundant due to the clay minerals present in the soils.

While I understand that the genus Disa is not widely grown by many hobbyists, and that they are part of the Orchidoideae subfamily, as opposed to the subfamilies Epidendroideae and Cypripedioideae, (the 2 subfamilies of orchids that many people tend to grow in the hobby), they are still classified in the family Orchidaceae, and although Orchidoideae are distantly related to Epidendroideae or Cypripedioideae, they are still related. If this was true for all 3 subfamilies of orchids, then the 4th and 5th subfamilies should follow suit, (I'm referring to subfamilies Vanilloideae and Apostasioideae).

If I were to follow logic, following the path of evolutionary pathways, I just cannot find any evidence that supports that orchids in general do not take in fairly large quantities of K+ themselves.

[isurus79]

This is about the epiphytic stage of strangler figs:

"During their epiphytic stage the figs are rooted behind the palms' marcescent leaf bases. Material trapped behind the leaf bases is higher in organic matter, nitrogen, magnesium, and potassium than soil from the ground near the palms. The suggestion that nutrient availability to epiphytes is high is supported by the observation that concentrations of several nutrients, including N, P, and K, are significantly higher in epiphytic leaves than in tree leaves."

Found here: JSTOR: An Error Occurred Setting Your User Cookie

"In Manaus Brazil, rain brought 3 kilograms of phosphorous, 2 kilograms of iron, and 10 kilograms of nitrogen annually to one hector of forest (Butler 4/10/2007). Nutrients are also available from dust and particles that are caught in the roots and nutrients from decaying organisms."

Found here: Epiphytes: An ecosystem contained within an ecosystem FINAL

[King_of_orchid_growing:)]

Also, if you can supply evidence that supports that mangroves take up NaCl in large quantities that would be great, because as far as I know, mangroves may have adapted to live in areas of high levels of NaCl, but I think that they've adapted mechanisms to control the amount of Na+ and Cl- ions getting in and out of their cells. And I also have a feeling that K+ may be involved in this.

With such high quantities of NaCl, if the mangroves were not controlling its uptake, I don't think they'd be alive.

I'm also not saying that K toxicity can't happen at all, it probably can, but the issue is more about how likely it is to occur given that we don't get trigger happy and start pouring on the K+ thinking that it'll help situations.

Seeing how things are in the hobby already, I don't think there is a real concern.

And quite frankly, there is currently no reliable evidence supporting a real concern for K+ toxicity.

[POLKA]

Well,
I thought that regardless of the amounts of calcium, magnesium, and potassium in solution, the cation of the potassium is so easily absorbed as to block / interfere with the absorption of the other two -- hence, you reduce your potassium in solution to allow the others to be more readily absorbed.

this is a nutshell is what I thought the original argument was started by.

electrically (at the atomic level of these elements), this makes sense to me.

Rex

[DavidCampen]

I said:
So, do we agree that potassium ion does _not_ bind to potting media in preference to calcium ion or magnesium ion?

And you replied:

Originally Posted by Ray

No, I don't agree.
While I have no references on that specific subject - it is SO difficult to find specific info relating to orchids only - my understanding of the underlying chemistry tells me that when exposed to a solution bearing equal concentrations of the three ions, the K will be more readily captured.

Your reply had no relevance to my statement. You keep saying that potassium binds more strongly to potting media than does calcium or magnesium. Every time I challenge that statement and say that it is incorrect you change the subject. This seems to indicate that you understand that potassium does _not_ bind to potting media more strongly than calcium or magnesium but for some reason you don't want to admit that.

Actually, in my opinion, whether potassium or calcium and magnesium bind more strongly to potting media really has no effect on the potassium toxicity thesis but you and Lockwood seem to think that it does.

[King_of_orchid_growing:)]

Originally Posted by POLKA

Well,
I thought that regardless of the amounts of calcium, magnesium, and potassium in solution, the cation of the potassium is so easily absorbed as to block / interfere with the absorption of the other two -- hence, you reduce your potassium in solution to allow the others to be more readily absorbed.

this is a nutshell is what I thought the original argument was started by.

electrically (at the atomic level of these elements), this makes sense to me.

Rex

I believe I understand what you're saying, but I'll say that it might not be working like how you mention it to work.

Being that I've not studied plant cell biology...

Based on the basics of what I understand about neuronal cell biology in general in respect to the ions mentioned, (K+, Mg2+, Ca2+, Na+, Cl-), a plant cell may work similarly to how a human neuron works in the sense that they may not only allow these ions to pass in or out of the cell passively via diffusion, but there may also be special proteins embedded in their cell membranes (or perhaps cell walls, idk), that control the movement of these ions. These special proteins may be in the form of ionic pumps or channels.

Simplistically speaking:

When there is movement of one particular type of ion in or out of the plant's cell, it might trigger these pumps or channels to initiate movement of other ions in or out of these cells.

I think this is closer to how it works.

I could be off by a bit or I could even be missing some steps in there, but you get the gist of what I'm trying to say.

For a basic example of what I mean:

If a plant cell allows K+ to enter the cell, it may prompt another cell to take in Ca2+. The more K+ is moved, the more Ca2+ may be needed.

Since Ca2+ has to be in some sort of balance with Mg2+, that's where Mg2+ enters the picture.

What I'm saying in this example is not entirely accurate to plants, but it may be a close approximation to what is really going on.

I'd have to take super high level botany or plant cell biology classes to even get close to understanding this.

With that said...

Someone who is better versed in botany please do speak up and correct me if I'm wrong, but I believe that plant cells are able to control what goes in or out of them to some degree, and that it is not solely passive absorption.

Without knowing the specific details, the whole topic on mangroves that Ray brought up is actually a point in my favor, because I was right, they do control NaCl going through their systems. Which in turn would begin to give people a clearer understanding of what I'm saying here in this particular post with plants in general being able to control movement of certain ions in or out of their cells.

One piece of evidence supporting the mangrove thing is here:

http://images.nationalgeographic.com...1284232047.pdf

Here's another mangrove article:

Mangrove Morphology & Physiology

Like I said, this topic is complicated. I only ventured to take a stab at it because I felt something needed to be said given the context of how this thread was going.

---------- Post added at 09:30 PM ---------- Previous post was at 09:16 PM ----------

I do want to point out that I do agree with what Ray had said in one of his earlier posts in this thread to some degree...

What is it that I agree on?

Well...

I'm assuming here, only because I have not studied this before, but -


I think that Ray might be right about energy potentials to some degree.

The movement of ions and their function in plants seem to point to energy for performing physiological tasks and for the purposes of intercellular communication.

Again, if I'm off, someone who is knowledgeable please do speak up.

[Ray]

David,

Nowhere in any of my posts have I "changed the subject" when responding. Instead I have tried to explain how I consider disparate instances of things that appear to come to some confluence of concept MAY be an indicator that they MIGHT be leading lot a valid concept. In some circles, that's known as open-mindedness. I get the impression that you firmly believe that whatever you have already learned or read is gospel, and not ever to be challenged.

I also find it humorous, yet sad, that you tried these same arguments over at Slippertalk, did not gain a strong following, so abandoned that, choosing to raise the same arguments here. I don't think any of your arguments are any stronger than anyone else's, or than they were there.

You are entitled to your own understandings and opinions, and I don't believe I-, or anyone else, has stated they were wrong. At least have the decency to allow others to express theirs without a "Jane, you ignorant slut" attitude.

Enough, already.

__________________

King,

I think the term "toxicity" may be getting a bit over-played or over-interpreted in this case. (David will likely accuse me of changing the subject again, but...) while in the mollusks, the excessive potassium may very well be truly toxic, in the U of MD study with people, the symptoms were of a far lesser degree, but still negative.

One of Rick Lockwood's considerations early in his raising of the potential K issue, was the long-term decline of plants, or the fact that some observe that plants do great for years, then just flat crap out. He theorized that it MIGHT have something to do with potassium buildup. That will not be known definitively for a long time, and I'm glad to be part of the group that is open-minded enough to participate in the experiment. I have tried to explain why I have some "buy-in" to the concept, but others apparently feel its appropriate to dismiss that.

I will state clearly that I do not think the chemistry of tissue samples necessarily reflects the chemical requirements of the living creature analyzed. It would not surprise me, however, if the tissue sample was more indicative of the chemistry of the environment in which the creature lived.

If the former was absolutely true, one might conclude that people in the US need high levels of fats and sugars in their diet to be healthy.

Plants are extremely - although not entirely - passive in their uptake of chemicals. If that was not true, then we would not have any availability of systemic pesticides that are poured in the soil and found in the leaf tissue. That, alone, supports that what's in them may not be a good indicator of what they require - I have seen no literature suggesting that acephate- or imidicloprid metabolites are required nutrients.

If you talk to folks with advanced degrees in plant physiology and nutrition, you will get the admission that "nobody really knows" what's going on in this field. There is only experimentation to rely on, and even those results are open to interpretation. The myth that high phosphorus promotes blooming in an otherwise healthy plant is a prime example. And despite David's disregard of the fact, there is very little research on orchids (although it is growing), and if you read some of those that are out there, we learn there is a substantial difference between the physiologies of terrestrial and epiphytic plants.

I don't know if the same is true among growers of other plants, but it is amazing to me the vehemence with which folks argue about stuff in the orchid community. It is especially interesting and strong with fertilizers, which none of us knows - for a fact - "crap" about, yet folks freely attack opinions.


Ray Barkalow
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[tucker85]

I didn't mean to initiate a slug-fest with this thread. I was hoping we could keep this discussion civil. Fertilizers seem to be in the same category as politics and religion when it comes to evoking emotional responses. Never-the-less my orchid growing techniques have improve tremendously by listening to other growers ideas and then experimenting for myself. Many of the suggestions I've heard over the years have not seemed to benefit my plants at all so I disregard them. Occasionally I run across something that helps my plants tremendously, so I incorporate it into my own orchid culture. Seaweed extract was one of those rare beneficial finds. And now I've discovered that a calcium/magnesium supplement also has a dramatic beneficial effect on my orchids. It was only after discussing it on this forum and some others, that I realized what was happening. In my specific case, the fact that my orchids were getting mostly rain water during the summer and municipal water in the winter explained why I needed to give my plants cal/mag during the summer. If I didn't have these forums available to me I probably never would have figured out what was happening with my orchids. I, for one, am grateful for these discussions, even when they get a little heated.