Air movement improves orchid nutrition

[K-Sci]

Originally Posted by TZ-Someplace

I don't recall, other than it was a recent factoid that stuck in my head rather than a research paper. It it looks like a google search on

[root tips and calcium uptake] will give results like this

Match calcium application to active root growth | Yara Australia

This article begins by saying "Calcium uptake by plants is dependent on new root growth and effective transpiration." The "effective transpiration" appears to support what the original post suggests - that increased transpiration increases nutrient uptake at the roots. Unfortunately, the article is incomplete.

Because grapes primarily absorb calcium through root tips, the article recommends timing the application of 20-25% of calcium additions to coincide with the second root flush in order to aid root growth in permanently planted crops such as grape vines.

I am wondering if the root tip absorption of grapes generalizes to orchids. Epiphytic orchid roots have a very different anatomy.

The article you cited states "In older roots once the casparian band has formed, it blocks calcium transport through apoplast cells in the root."

The apoplast is the supposedly dead part of the plant tissues including their cell walls. Apoplast cells play a major role in both water and nutrient transport in general.

The Casparian strip is a band of cell wall material deposited in the radial and transverse walls of the endodermis, and is chemically different from the rest of the cell wall. The exodermis is a membrane of variable permeability responsible for the radial flow of water, ions, and nutrients.

Online papers indicate that the velamen of epiphytic orchid roots has a similar morphogenesis to the exodermis of terrestrial plants. It is a fact that velamen is a highly specialized porous root covering that takes in both moisture and nutrients. I've been unable to find papers that describe the existence and role of a Casparian strip and/or apoplast cells to orchid roots.

-Keith

---------- Post added at 12:19 PM ---------- Previous post was at 12:11 PM ----------

Originally Posted by Shadeflower

... I will add my latest observation that for every ppm of magnesium you add you should add an equal amount of phosphorous (as can be seen on the mulders chart keith showed) and incidentally it turns out for every ppm of Phosphorous one should also add an equal amount of Potassium.

If you are right it would mean the formulation of K-lite is ill-advised. Adding 3ppm Mg but only 1 ppm P and K. Are there academic sources you can identify for the ratios?

-Keith

[Ray]

Keith,

In ordinary plants, I imagine air movement might enhance transpiration, but considering the metabolic processes of many orchids, I don't think that translates well.

One might argue that CAM plants, because they tend to open the stomata at night, when the relative humidity is maximized in rainforests with little air movement, ought to have very poor transpiration rates.

I think this may be yet another case (and I do it, too) in which we are trying to focus on a single facet of a very complex set of parameters.

[Shadeflower]

Originally Posted by K-Sci

If you are right it would mean the formulation of K-lite is ill-advised. Adding 3ppm Mg but only 1 ppm P and K. Are there academic sources you can identify for the ratios?

-Keith

Not really. Here is a rough guide of what I have also observed. Feed less N in winter during reduced growth and more K to strengthen cell walls to handle the cold.

https://www.growingagreenerworld.com...hat-they-mean/

edit: I need to add a disclaimer that the person who wrote that guide believes that feeding more P will encourage a plant to flower and this is wrong thinking. A plant decides what it wants to do and our job as gardeners is to support that. If it wants to grow and we try to force it to flower the plant will carry on growing but will not be receiving the right ratio of nutrients to grow well. At the same time if the plant wants to flower and we carry on feeding nutrients promoting vegetative growth the plant will develop deficiencies and not flower as well.

Whether this helps, I think so but it does surprise me how little literature there is on the topic.

As to K-lite, it's a brand new product. I would not use it myself, maybe it is great for paphiopideliums.

Without K my plants would drop more lower leaves and develop more brown spots at the leaf tips.

Then in spring when temps warm up and growth picks up you want to feed more Nitrogen to promote fast vegetatice growth but not in winter.

So again maybe the K-lite has it's place but nobody has bothered to explain to me exactly what that is, for paphs only? Good for all orchids (well not in my opinion), good all year (again not in my opinion, too little K for winter)

Take what you must from that Keith, it's just my conclusions by now and still an ongoing evolving journey overall. Every grower goes through a period of trying out a bit more Ca, a bit more Mg a bit more N. I am here to represent the ignored ones that even got left out of the latest feed entirely and I am saying no, they are important at certain times of the year. But again highly subjective.

Some might even go so far as to say considering the vast range of difference someone using k-lite compared to someone using a balanced feed is, does it really make any difference at all? But that would be the wrong conclusion to take. Then again the K-lite grower would say they get better floewering and the balanced feed grower would say orchids are not just grown for a summer display, the important thing is to get better results year after year which includes making sure the orchid doesn't develop too many problems. The weaker the orchid the more it gets susceptible to cold damage, heat stress, pests attacks and fungus which all affect future flowerings.

---------- Post added at 08:15 PM ---------- Previous post was at 07:11 PM ----------

So that article mentiones a "winterizer" which I had never heard of before and although I feel this is veering far off toward how to grow grass this article shows how much debate there is on the topic.

What is a lawn winterizer? - Natures Lawn & Garden

We could carry on that debate all night long...

That aticle atleast seems to promote that K-lite is also a good winterizer.

[TZ-Someplace]

"I've been unable to find papers that describe the existence and role of a Casparian strip and/or apoplast cells to orchid roots. "

Wikipedia explains apoplast pretty well. And I did a quick google image search and the orchid roots I found had endodermis layer marked, and you can see the pink staining of the casperian strip. If a plant did not have some sort of barrier to free/extra cellular ion flow it would leach out all of its extra cellular nutrients when it rained. As it is that only happens at the root tips.

This article may also explain why calcium is mostly taken up by the root tips, at least in nature

Frontiers | Root Exudation of Primary Metabolites: Mechanisms and Their Roles in Plant Responses to Environmental Stimuli | Plant Science

Organic acids released by the tips/hairs could be mobilizing calcium in nature and making it available for uptake. This obviously wouldn't matter if you are bathing your roots and spraying your leaves with soluble calcium.

[Ray]

Originally Posted by TZ-Someplace

This article may also explain why calcium is mostly taken up by the root tips, at least in nature

Frontiers | Root Exudation of Primary Metabolites: Mechanisms and Their Roles in Plant Responses to Environmental Stimuli | Plant Science

Organic acids released by the tips/hairs could be mobilizing calcium in nature and making it available for uptake. This obviously wouldn't matter if you are bathing your roots and spraying your leaves with soluble calcium.

That's a very interesting article. Thanks for the link.

One thing that "itches my mind" is that the article talks about root/soil interaction, where the exudation is significantly controlled by the proximity of the soil and soil-borne microbes with the root tips. The degree of that is entirely different between terrestrial and epiphytic plants, so are the processes identical?

[K-Sci]

Originally Posted by Ray

One thing that "itches my mind" is that the article talks about root/soil interaction, where the exudation is significantly controlled by the proximity of the soil and soil-borne microbes with the root tips. The degree of that is entirely different between terrestrial and epiphytic plants, so are the processes identical?

This is the question I asked, investigated, and posted about above. The morphogenisis of orchid root veliman appears to be analogous to the exodermis of terrestrial plant roots where Ca transport is blocked, but nearly all the basic functions of the two root types are very different.

Orchid aerial roots are associated with symbiotic fungi or bacteria that have their own nutrient requirements and fix nutrients from air and water. Veliman is comprised of dead cells that act as a sponge to hold moisture and nutrients. There is photosynthesis in orchid roots that would not serve a purpose in terrestrial plant roots.

Do veliman or associate cell walls block transport of calcium? It would need access to a much better tool than google to research papers on the topic.

-Keith

[SouthPark]

It is a good topic. And the important 'factor' here is ----- the benefit this has for the orchid. So - whichever way that the calcium gets in (if it is there and is able to be acquired by the orchid) ------ we know that the healthy orchid generally develops roots - whether we like it or not. So the calcium is going to get in one way or another - through whichever portion of the root is relevant for Ca (etc.) intake.

We just have to provide the orchid satisfactory growing conditions (temperature, humidity, nutrients, elements, lighting, air/oxygen etc, and avoid root drowning) and ward off attacks from nasties.

Fully understanding the mechanisms of how it gets in is certainly beneficial. But we do know that ---- the Ca etc is going to get in. So does it critically matter what the mechanism is (?) ----- except for pure understanding (which is still interesting - for science and knowledge, and possibly application).

Getting back to the air-movement aspect - from the first post ------ we could probably say that under certain conditions - whatever they may be ---- to be determined, air-movement could possibly 'improve' orchid nutrition - or more concisely ----- improve rate of distribution of elements etc within the orchid - dependent on rate of transpiration, or whatever goes on inside the orchid.

[Shadeflower]

totally agree SP,
we are interested in what makes our orchids produce that one extra flower this year

what part of the root takes in what won't do that.

So I think the original question goes along the lines of will an orchid grow/flower better with more airflow than with limited airflow? I think the "distribution of nutrients around the plant" is an important part of it but again we just care that it results in that additional flower at the end of the day.

So has anyone done a detailed field trial to try with fan, without fan, different speeds? We need some experimental data to determine what gives the best results.

So far at mine it has been too varied. Sometimes minimal ventilation gives great results, too much ventilation usually causes me problem tbh cause my root tips dry up which I hate happening.

But I had never really considered nutrient uptake. My belief is that they take what they want.
The belief to pump the orchids full of nutrients is not a belief I share. Each chlorophyll cell needs a magnesium particle at it's center, it then needs a bit of all the rest to build it. Without magnesium the plant would literally run out of building blocks. Will pumping them full of magnesium make them build more chlorophyll? Maybe but all the elements of growth must be fulfilled. If a plant is getting all the magnesium it needs then feeding it more or trying to make it absorb more by making it transpire more is not something I have heard to be benefecial before. With fast growing plants generally you have to replace all the air in the grow area every hour for optimal growth but orchids grow so slowly does the air have to be replaced as much?

[K-Sci]

Originally Posted by SouthPark

...we could probably say that ... air-movement could possibly 'improve' orchid nutrition - or more concisely ----- improve rate of distribution of elements etc within the orchid - dependent on rate of transpiration, or whatever goes on inside the orchid.

There are practical implications for treating suspected orchid nutritional deficiencies. Treating this or other nutrient deficiencies may be more effective or work more quickly in an environment with modestly high RH and copious air movement. Providing both is desirable regardless.

One implication for this topic has me thinking about past failures getting orchids to grow well in an enclosed terrarium. A stagnant environment with very high humidity may potentiate nutritional deficiencies.

-Keith

[SouthPark]

Originally Posted by K-Sci

Treating this or other nutrient deficiencies may be more effective or work more quickly in an environment with modestly high RH and copious air movement. Providing both is desirable regardless. One implication for this topic has me thinking about past failures getting orchids to grow well in an enclosed terrarium. A stagnant environment with very high humidity may potentiate nutritional deficiencies.

This could definitely be studied. One interesting condition is the one that shade mentioned - about flasks. I don't know if anybody has done it before ------ but would definitely be interesting to see if a flask that is made big enough - even fitted with sterilised media, such as scoria etc - with agar gel and all within it, and some means to introduce nutrients under sterile conditions (to maintain sterile conditions) ------ could possibly allow an orchid to grow to full flowering size - and produce flowers ------ without air-movement, or pretty much no air-movement at all, and with relatively high humidity.

As for non-sterile environments. Air-movement could possibly cut down on certain unwanted things growing on the orchid that could impact negatively the health of the orchid - and also allow for water movement, oxygenation of water, and media ---- to help the roots along.

But - back to the big sterile flask environment. If an orchid could possibly grow nicely in a big enough flask ------ then that that would be nice. A nice reference maybe. And then could see what happens when air-movement is introduced - to see what differences there are ------ in general. Such as general size of orchid, leaves, growth rate etc. This - like most things - would take time and effort ------ to test out.