Air movement improves orchid nutrition

[Shadeflower]

Originally Posted by SouthPark

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.

I tried with my dendrobium normanbyense this year which has been flowering for the past month.

It is grown in a closed aquarium, 1 cm air gap at the top for ventilation, I do not use a fan in there. I just tried without and I didn't feel I needed it.
Humidity stays fairly constant. It gets heated to 21 degrees during the day and then cools down at night down to about 16 in winter.

So the dendrobium I have in there flowered no problem.

In fact I use this aquarium for problem orchids that have little roots. The high humidity and little air flow + I presume the daily heating action of the heat mat I use promotes good recovery.

I only have orchids in there that are smaller than a fist. Bigger orchids would probably need a bit more air exchange.

But what I cannot say is if the orchids might grow faster if I provided more air exchange, all I can say is they grow well and do not rot as one might be worried about with no air circulation.

It should only be done if you monitor humidity. If it stays cold, humid and with too little ventilation that automatically promotes mold. One has to be aware that the substrate has to be inert (sterile) otherwise things probably would start rotting.

[SouthPark]

Excellent information. Thanks very much shade for sharing those details.

[Ray]

OK. Admittedly, I am in the middle of my first cup of coffee after a period of very deep sleep, so I don’t know how well my brain is functioning yet, but a couple of things jumped into it.

We have failed to define “air movement”. In the greenhouse environment, stagnant air can lead an increased incidence of pathogen attack, while too much of a breeze can lead to desiccation. Where, in that spectrum, might the “improvement” be?

There is also, of course, the question, “would it make a significant difference?”. This is a great mental exercise (and you all know how I love those), but considering the extremely low demand orchids have for nutrition, would such an “improvement” even be noticeable?

[K-Sci]

Originally Posted by Shadeflower

It gets heated to 21 degrees during the day and then cools down at night down to about 16 in winter.

With this day/night differential in an enclosed terrarium at ~100% RH, wouldn't there have to be condensation? If there were the bacterial and fungal infections would seem to be unavoidable. I'm wondering if your 1cm gap was keeping the humidity considerably lower than 100%. What do you think?

-Keith

---------- Post added at 08:27 AM ---------- Previous post was at 07:54 AM ----------

Originally Posted by Ray

OK. Admittedly, I am in the middle of my first cup of coffee after a period of very deep sleep, so I don’t know how well my brain is functioning yet, but a couple of things jumped into it.

Okay, I'll try writing a reply with a similar coffee efficiency.

There is also, of course, the question, “would it make a significant difference?”. This is a great mental exercise (and you all know how I love those), but considering the extremely low demand orchids have for nutrition, would such an “improvement” even be noticeable?

According to the Ca deficiency article that prompted me to start this topic, airflow makes a difference. How this was determined was not mentioned.

On defining airflow...

At 80%-90% RH, the airflow from a window box fan blowing directly on orchids from roughly 3' (1m) away did not cause desiccation even with very warm leaves (e.g. tens of linear feet per second).

On the other hand, in Wisconsin and Maine growing indoors in winter with very low RH (e.g. around 25% or less) I did see signs of stress with almost no airflow.

-Keith

---------- Post added at 09:11 AM ---------- Previous post was at 08:27 AM ----------

The paper posted by TZ-Someplace

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

included a link to this one on Ca transport in Arabidopsis: Glutamate-Gated Calcium Fluxes in Arabidopsis1 | Plant Physiology | Oxford Academic

This still doesn't provide a tie-in to orchid roots where the fungus/bacteria are inside rather than outside the root.
-Keith

[SouthPark]

Originally Posted by Ray

We have failed to define “air movement”.

We can consider it as not yet defined ----- the sort of air movement (speeds, directions etc). Not 'failed to define' as such. It is just to be defined.

[DirtyCoconuts]

i am enjoying this discussion and i want to add one thing i have observed in the loose, inorganic medium i use. the increase in the air movement does certainly result in the plant and medium drying out faster and i notice that if i do not flush the plants regularly i see more salts develop on the lava rock and LECA which i attribute to the constant wetting and rapid drying. If the salts are in solution and the wind dries up the water, the salts have to go somewhere.

[Shadeflower]

I'm liking the latest conclusions. So if I was an even better grower and had a bigger collection then I would have 1 circulating fan inside the grow area and an extraction fan that would replace all the air in a 24 hour period.

I feel that is probably what would give good results. But I have taken some shortcuts. Yep I hardly use extraction fans. I probably should use them more. But it's an extra hassle, cost, whatnot.

I kind of base this on my experience with crickets and locusts which obviously need oxygen to breathe just like plants need C02 but it is surprising how little air they need. I could easily stick a colony in a box and they'd have enough to last them for a month.

My orchids I check on them every few days and provide fresh air. Like mentioned it's a shortcut that is probably not the best I could be providing. Not sure if that is useful info at all..

[Ray]

Originally Posted by DirtyCoconuts

i am enjoying this discussion and i want to add one thing i have observed in the loose, inorganic medium i use. the increase in the air movement does certainly result in the plant and medium drying out faster and i notice that if i do not flush the plants regularly i see more salts develop on the lava rock and LECA which i attribute to the constant wetting and rapid drying. If the salts are in solution and the wind dries up the water, the salts have to go somewhere.

By contrast, in my enclosed and well-sealed greenhouse with very high humidity, changing fan speeds appeared to have very little impact on the evaporation.

[K-Sci]

Originally Posted by DirtyCoconuts

... i notice that if i do not flush the plants regularly i see more salts develop on the lava rock and LECA which i attribute to the constant wetting and rapid drying.

Excellent point. Those salts, depending on what they are, could relatively easily cause changes to an inert media pH. Hard water generally includes calcium and magnesium carbonates/bicarbonates/sulfates which tend to raise the pH. IIRC, a moderately high pH (e.g. 7.5-8) will decrease phosphorus, iron, manganese, boron, copper, and zinc availability and slightly increase the availability of Calcium, and Molybdenum. Trace elements are probably not a significant factor but I assume they must be provided in the water when using an inert media. Unless the pH went over 8.0, the phosphorus and calcium would be the nutrients affected the most. I'm not sure where to go with this, however.

-Keith

---------- Post added at 04:49 PM ---------- Previous post was at 04:41 PM ----------

Originally Posted by Ray

By contrast, in my enclosed and well-sealed greenhouse with very high humidity, changing fan speeds appeared to have very little impact on the evaporation.

Same here. The RH in my greenhouse is usually 70-90%. I see no deleterious effects even on large white phal flowers that are blowing back and forth by inches in the breeze. My greenhouse fans blow above the orchids, but this Phal's flower stalk sticks up enough to get the full gale. I also didn't see any drying efffects when I had window box fan blowing directly on orchids from about 3' away. The fan was used to cool them after I removed the shade cloth this fall.

-Keith

[Orchid Whisperer]

Originally Posted by K-Sci

Discussion topic: In an environment with good humidity, strong air movement improves orchid nutrition by increasing the amount of nutrient containing moisture taken in by the orchid's roots.

-Keith

?

No.

That's sort of like saying "not driving into a brick wall improves bone health."