Air movement improves orchid nutrition

[Clawhammer]

Great discussion, this is what I'm here for.

Good airflow absolutely increases transpiration by increasing evaporation at the stomata and therefore growth considering all other variables are in place to not bottleneck that growth. I am not entirely convinced it increases nutrient uptake because I don't think I fully understand the mechanisms involved in how orchids "grab" nutrients contained in H20. I don't think the increased transpiration discussion is as vital as it would be for fast growing plants or produce, but good to understand when making potting or growing environment decisions.

I found TZs point that airflow is beneficial for carbon fixation by maintaining high CO2 and low O2 inside the leaves very interesting.

I am not a micromanager but I am a geek who likes to know why. I was already convinced that airflow was a very important part of the mix for optimal health (reducing pests/disease/leaf burn) and this thread has reinforced that.

[rbarata]

Originally Posted by K-Sci

Wouldn't growing orchids at 100% RH for any period of time result in fatalities due to disease?

Well, some orchids grow in (or near almost of the time) 100% RH environments (cloud forests, for ex).

[K-Sci]

Originally Posted by TZ-Someplace

Throwing some pocket change into the discussion.

Your post was exactly the type of pocket change I was hoping for.

If only the root tips take in Ca, then trimming an orchid's roots during repotting would disable its ability to take in Ca. If you have a source for this, please post it. I'd like to check it out.

Thanks!
-Keith

[TZ-Someplace]

Originally Posted by K-Sci

Your post was exactly the type of pocket change I was hoping for.

If only the root tips take in Ca, then trimming an orchid's roots during repotting would disable its ability to take in Ca. If you have a source for this, please post it. I'd like to check it out.

Thanks!
-Keith

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

[Roberta]

Trimming roots? I don't do it. With Cyms, some people do because those are such root machines, and there will be copious new ones. But still, I can't bring myself to cut a good root. (With Cyms, some get broken anyway, but I try to minimize it)

[K-Sci]

Attachment 156313

Originally Posted by Shadeflower

Now I'd only ever watered it up to a maximum of 180ppm but because the plant was still drinking water but clearly not the nutrients they were building up in the pot over time.

Do you suppose that the evaporation was removing only the water and leaving the nutrients behind? That would be my assumption, anyway. I would expect the water removed from the media due to evaporation to be much, much greater than water removed by the plant roots.

I have read that plants can influence through chemical reactions in their cells which nutrients specifically to absorb. I have it bookmarked somewhere...

If you find the link, please post it or send it to me in a message.

Anyway yes nutrients get locked out by other nutrients.

To illustrate your point, I've attached a standard chart of the effects of pH on terrestrial plant mineral absorption and another on mineral absorption inhibition/potentiation relationships.



I don't think "locked out" is the best choice of words as it implies complete blocking, as in zero passage beyond a point. I'm sure these are not brick wall relationships, but rather sliding scales.

As such a plant that is transpiring more, either in hot weather or from a fan could benefit from more plain water in between watering's (since it is transpiring more water). Adding the same amount of fertilizer would not mean the plant would absorb more, it will absorb what it needs

If it is what you are saying, I think you've gone too far in concluding that plants only absorb the nutrients they need, then stop. An example is nitrogen where the plant will absorb more if more is available until it reaches toxic levels that disrupt the plant's physiology and can kill the plant. Many micronutrients are likewise toxic when present in excess long before they reach the level that the salts burn the roots.

However, if the goal is to prevent deficiencies, the ideal that air movement may help increase nutrient availability and absorption by the roots would still apply, would it not?

-Keith

[K-Sci]

Originally Posted by Roberta

Trimming roots? I don't do it. With Cyms, some people do because those are such root machines, and there will be copious new ones. But still, I can't bring myself to cut a good root. (With Cyms, some get broken anyway, but I try to minimize it)

I share your sentiment on this, for sure. On the other hand, considerable root loss often occurs for newly repotted plants whether intentional or otherwise. Wouldn't you agree? The effect would be the same.

-Keith

[Roberta]

Originally Posted by K-Sci

I share your sentiment on this, for sure. On the other hand, considerable root loss often occurs for newly repotted plants whether intentional or otherwise. Wouldn't you agree? The effect would be the same.

-Keith

Root loss happens as the plant transitions to new medium, but before they die, those old roots can hydrate the plant while the new roots are developing. I think people trim Cym roots to fit plants into a pot... the Procrustean bed approach. That hurts!

[TZ-Someplace]

Who is going to make a practice of trimming active roots and repotting when new growth is pushing up besides me when I'm playing mad scientist (and how fast are lateral roots going to pop out to help recover)?

There is the usually logical timing of new root initiation/growth that coincides with the calcium need of new growth. There are of course often exceptions to human reasoning in nature and I wonder what the calcium, root growth, growth stimulation hormone relationship is with the temperamental bifoliate catt species that (I hear) hate it when you even think about touching their roots and repotting them?

I can't wait to set up a plant torture dungeon again. I have been away far too long. MuuaaaaaHaaaHaaaa!

[Shadeflower]

Originally Posted by K-Sci

Do you suppose that the evaporation was removing only the water and leaving the nutrients behind? That would be my assumption, anyway. I would expect the water removed from the media due to evaporation to be much, much greater than water removed by the plant roots.
If you find the link, please post it or send it to me in a message.

Keith, the article I linked explains what I mentioned already.
I honestly do not know what happens when a plant absorbs too much N. I do believe plants take what they need so we assume different things there. I believe there is a range that works so yes maybe they will take in more N at times as long as it is within the range they can use but I just cannot see them taking in so much do do themselves damage. But you are right that is purely my specualtion just because I have never seen what you talk about, ever, not with any plant I have grown. I have overfertilized and caused leaf and root damage. Overfertilzing can cause an entire orchid leaf to drop off, not just a lower one. I have never bothered to stop and think ok the plant took in too much N, no I think "oh no I overfertilized"
The bottom line is not too feed too much whether it is because the plant takes in too much or my reason that the leaf gets damaged might be the same.

Ok then to address your further assumption that evaporation plays a bigger role than the roots absorbing the water. This really depends on the orchid. If we are talking about a neofinetia then I agree with you. If we are talking about a dendrobium nobile, not at all.
So it makes a little difference how much the orchid drinks but let us assume we are talking about a small slowish grower in a substrate that evaporates lots then you might be absolutely right keith but I grow hundreds of orchids. I fertilize very weakly and I try to fertilize so that the plants get what they want in my conditions based on the evaporation in my pots. Previously I had not thought much about it but there is a connection I have noticed by now. Like in my den nobile pots where they drink more than the pots evaporate there will never be salt accumulation. But I have caused problems with my neo's doing the same, this is true. Basically the neo pots would evaporate more, my neo's drink very little comparatively so the pots do evaporate more. All this means is I should in future be using more plain water to compensate for the evaporation or check the pot tds to make sure it stays under 200 long term.

But ultimately it seems we assume 2 different things and thus believe slightly different things, if your initial assumptions on whether a plant absorbs all it gets and that evaporation plays such a great role then we will always have differnt conclusions.

My view is just that the more a pot evaporates the more water you have to provide.

If one person waters with 1 liter of water and adds 1 scoop of fertilizer

and another person has double the evaporaton in his pots then the second person has to use 2 liters of water but still should only add 1 scoop. As a result the first person will have a tds roughly twice as high as the second person.

But I don't really feel like any of this is beneficial in getting anyone to grow better orchids... Just posting my point of view but at the same time I don't think anything we have discussed so far has been truly revolutionary discoveries, apart from plants requiring a gentle regular supply of C02.

I just realized a a further point, if orchids absorba all you feed, why do some of mine not? And the tds rises if I'm not careful? If the orchids absorbed all I was giving them then the concentration in the pots should never be able to double over time... just a thought