Wild Orchids - Roots and Nutrition

[keithrs]

Andy/Harry do recommending watering at night in summer months to allow the plants to soak up more moisture. I water when I feel like watering. I mostly water before and after work but some times it pull out the "fire hose" and water at night. Especially on warm, dry days. In the winter time most of my plants stay out side. They will stay moist for for weeks. I had two plants show signs of rot. Both where warm growing plants and I think there cell walls broke down allowing rot to set in. I truly believe that most folks get rot issues because they have a very low amount of beneficial microbes in there collection. I was reading an article about 6 month a go about how Azotobacter and Azospirillum bacteria pull N out of the atmosphere and feed to the plants thought there leaves, stems and roots. Also help produced some sorta antibiotic that helped fend off disease causing microbes. I think its very possible for (wild)orchids to be associated with these N fixing microbes along with other "plant protecting" microbes.

 

[KyushuCalanthe]

Nice habitat shots Lance. Seeing orchids in the wild rocks!

I've never seen an epiphytic orchid growing naturally on a truly sterile surface. Lichens would provide some protection from desiccation, but something more seems afoot. Given the complexity of relationships between organisms in the wild (fungi weighing in heavily), I don't think it is possible to generalize too much about how or why a particular plant grows where it does.

 

[Ray]

Andy/Harry do recommending watering at night in summer months to allow the plants to soak up more moisture.

You think that's primarily because of the very dry atmosphere? RH naturally goes up at night, as the temps drop, slowing the evaporation rate.

 

[keithrs]

You think that's primarily because of the very dry atmosphere? RH naturally goes up at night, as the temps drop, slowing the evaporation rate.

Yes, Thats the thought behind night watering here. Its not uncommon to see single digits RH and blazing hot sunshine. Plants that need high RH shrivel and dead a very slow death.

On a side note.... I remember a thread by ChrisFL where he mentioned that tropical regions get lots of rain at night. Those regions also have very high RH and plants in that region dont have rot issues. I'm curious if the microbes that cause root rot become active as temps fall below 60 or so? I have zero issues in the spring, summer and fall. As temps drop in the winter is when I become nervous.

 

[Rick]

I was recently looking for some in situ pics of nepanthes, and came across a link that had a bunch of in situ pics in Malaysia/Bornea. (Paphioboy probably linked on ST recently).

Lots of epiphitic orchids on smooth bark with no moss or lichens. Phalae appendiculata was the focus of several pics growing on smooth barked twigs. So nothing but direct stemflow uptake for those species.

 

[gonewild]

Lance, are you thinking that orchid leaves take up nutrients?

Yes they do take in nutrients through the leaves. I proved this to my self many years ago (nothing to do with science just learned it).

Our roots stay wet at night, even though we try to have dry plants by then.

OK here is where there might be a fine line about "wet".
There is a difference between 'staying" wet and "getting" wet.
There is also a difference between "wet" and "moist".

In nature orchid roots seem to dry out during the day whenever it is not raining. They are exposed to air and have great drainage. Now they don't normally get completely dry but they dry out. Humidity is lowest during the day so everything gets driest during the day.

Imagine the orchid roots are like sponges and soak up moisture that contains nutrients. The roots hold the nutrient rich moisture allowing the plants to take it in. But when a sponge is "wet" it can't soak up any new water and perhaps neither can an orchid root, so when the roots stay wet the nutrients may not be accessible to the plant.

So here is one concept. during the day orchid roots have some time to evaporate out water and become drier sponges. the surrounding environment, bark, moss, lichens, soil, leaf litter, ect. all are drier. Then night comes and the dew gets everything wet. As the surface of everything gets wet it dissolves all the accumulated surface nutrients and the nutrient ladden moisture is sucked up by the root sponges. Over night the roots remove the nutrients and the the next day a the humidity drops the roots dry out.
Of course day time rain alters this process but when we consider how much water comes with rainfall the nutrient supply is almost zero in the water.......
requires more thought so think about it.

I remember Andy's brother (of Orchids on a Stick) talking to our society. He told us to water in the evening. But his environment (CA) is very different from ours (MI).

Think about what I said above and how it might relate to this.
I have a lot more observations to write about as I get time. But the jungle is calling now.

 

[Rick]

so when the roots stay wet the nutrients may not be accessible to the plant.

chemicals travel through water (standing or not) via osmosis and active transport means.

As long as the plant is in contact with water, and the plant has a demand for a particular chemical, it will travel through the contact water into the plant.

Now if the water around the roots has a concentration of nutrients higher than the concentration in the plant then it will be able to passively transport the chemicals "uphill" into the plant, and the plant won't need to uptake bulk water to transport both water and nutrient into the plant at the same time (simple osmosis). If the external concentration is weaker than inside the plant the plant needs to uptake the water with nutrients to obtain nutrients. This is basic evapotranspiration which is generally a day/light requiring process.

Orchids are not different from other household plants like philodendrons that you can stick into water (like in a hydro or semihydro sytem) and have the roots become totally submerged, and still uptake nutrients by either osmotic or evapotranspiration mechanisms. There are also active transport mechanisms that generally require an exchange of one chemical for another at the root surface for uptake into the plant.

Think of your phrags that like to have "wet feet".

 

[Rick]

Osmosis can go both ways to transport water or solutes across membranes to bring around solution equilibrium. In some conditions having very salty concentrations outside the plant will suck water out of the plant to even out solute concentrations on either side of the root membrane.

 

[gonewild]

Osmosis can go both ways to transport water or solutes across membranes to bring around solution equilibrium. In some conditions having very salty concentrations outside the plant will suck water out of the plant to even out solute concentrations on either side of the root membrane.

This reinforces what I'm saying about wet verses moist....(sort of).

When water around roots is nutrient poor like in heavy rain it may draw nutrients out of the plant tissues while the moisture from dew may be richer in nutrients so the movement is into the plant.

 

[gonewild]

In the 27 years of growing slippers I don't recall crown rot and 9 out 10 times I water it is at "night". Night, meaning 5-7 PM after work or 3:30- 4 AM before work.

Like I have said orchids get wet at night in the wild, at least in the South American tropics. I have never see an orchid with crown rot or actually any condition resembling the "rot" problems we see in our collections.

I have/had basal rot but that happens because of the condition of the mix not my watering.

Yes. The condition of the mix is the problem. Maybe it is the fault or poor aeration or incorrect nutrition. We always have assumed it was the aeration but now with the results from K-lite it looks like it is a nutrition problem. Since orchids can grow with their roots pertinently in water we should not assume aeration.

In regards to orchids growing only where lichen is found. Isn't it possible that both are growing in the same location because its the best enviornment for both rather then one depending on the other nutrients?

It would seem that way but lichens source their nutrition completely differently than orchids. Lichens obtain their nutrients directly from the atmosphere. Orchids can take advantage of the lichen and get nutrients from them.

 

[gonewild]

Andy/Harry do recommending watering at night in summer months to allow the plants to soak up more moisture. I water when I feel like watering. I mostly water before and after work but some times it pull out the "fire hose" and water at night. Especially on warm, dry days. In the winter time most of my plants stay out side. They will stay moist for for weeks. I had two plants show signs of rot. Both where warm growing plants and I think there cell walls broke down allowing rot to set in. I truly believe that most folks get rot issues because they have a very low amount of beneficial microbes in there collection. I was reading an article about 6 month a go about how Azotobacter and Azospirillum bacteria pull N out of the atmosphere and feed to the plants thought there leaves, stems and roots. Also help produced some sorta antibiotic that helped fend off disease causing microbes. I think its very possible for (wild)orchids to be associated with these N fixing microbes along with other "plant protecting" microbes.

Q: How to get everything in a correct balance to keep orchids in the best health?

A: keep trying different conditions until one works.

If some people can water at night then why can't everyone?
Some factor or factors other than the water are what caused the rot.

Some things are simple. If you allow water to stand in the crown of a Phalenopsis plant at night it will probably get crown rot. But the problem is not the night water it is that the water stayed in the crown because the crown is pointing up like a vase. In nature Phalaenopsis are tilted downward so the crown drains naturally.

 

[gonewild]

Given the complexity of relationships between organisms in the wild (fungi weighing in heavily), I don't think it is possible to generalize too much about how or why a particular plant grows where it does.

I agree completely. We especially have the problem of working with so many different species from different environments.

What I actually trying to find out is what makes wild orchids grow poorly rather than what makes them grow well. The idea of looking for a common nutrient source is to see why K-lite is working so well at very low nutrient levels as compared to the old standards.
Is it simply the Potassium content in the plant?
Does the potassium content suppress beneficial organisms?
Does excess potassium factually cause the plant to be sensitive to rot?
If K-lite eliminates the rot problem can people safely water at night?
Will watering at night improve plant growth?

I'm not trying to prove anything I just am enjoying the search.
And taking pictures to share!

 

[gonewild]

You think that's primarily because of the very dry atmosphere? RH naturally goes up at night, as the temps drop, slowing the evaporation rate.

What I see here is a step beyond the night time humidity rise.

The humidity goes up so high that everything get wets with dew and it is almost like rain at night in the jungle from dripping dew.

 

[gonewild]

Yes, Thats the thought behind night watering here. Its not uncommon to see single digits RH and blazing hot sunshine. Plants that need high RH shrivel and dead a very slow death.

I think there may be a significant difference between high nighttime humidity and watering at night. Perhaps a better approach would be to raise the humidity without raining" on the plants, like a fogging system?

On a side note.... I remember a thread by ChrisFL where he mentioned that tropical regions get lots of rain at night. Those regions also have very high RH and plants in that region dont have rot issues.

Even without rain in the tropics everything gets wet at night. Even in the dry season when it does not even rain once a week everything is wet at night. We just finished 4 days of extreme cold temperatures here. One day the temperature was 29c at noon. As the front moved it it rained and the temperature dropped to 12c by night. Over night the temperature dropped to 9.6c and during the day never got above 12c.
4days later now the temperature is 28c. Cold and wet day and night and not a single plant in the jungle has rot from it.

I'm curious if the microbes that cause root rot become active as temps fall below 60 or so? I have zero issues in the spring, summer and fall. As temps drop in the winter is when I become nervous.

Temperature is not the cause but rather a catalyst.
So far the best clue we have is Rick's potassium toxicity theory. Maybe the potassium inhibits beneficial microbes?
This could be within the plant tissues or even in the immediate plant environment like around the roots or on the leaf surfaces.

 

[gonewild]

I was recently looking for some in situ pics of nepanthes, and came across a link that had a bunch of in situ pics in Malaysia/Bornea. (Paphioboy probably linked on ST recently).

Lots of epiphitic orchids on smooth bark with no moss or lichens. Phalae appendiculata was the focus of several pics growing on smooth barked twigs. So nothing but direct stemflow uptake for those species.

Can you post a link to the pictures?
Some lichens are very tiny and hard to see.
As well I still think some species can get nutrients directly from the tree bark when they get wet. Wet bark makes tea!

If they are growing on twigs where is the stem flow from? Most twig growers I see here are situated so they don't really get stemflow. They either are watered from direct rainfall of dew. Standing at the base of big trees in a rainstorm I stay pretty dry because the canopy sheds most of the water away from the trunk.

 

[gonewild]

chemicals travel through water (standing or not) via osmosis and active transport means.

As far as we know! At least that is what science believes today. oke:

As long as the plant is in contact with water, and the plant has a demand for a particular chemical, it will travel through the contact water into the plant.

Then why does a plant uptake too much potassium if it does not need (demand) it?

Now if the water around the roots has a concentration of nutrients higher than the concentration in the plant then it will be able to passively transport the chemicals "uphill" into the plant, and the plant won't need to uptake bulk water to transport both water and nutrient into the plant at the same time (simple osmosis).

A lot of orchids grow with their root "uphill" so does this rule still apply? oke:

If the external concentration is weaker than inside the plant the plant needs to uptake the water with nutrients to obtain nutrients. This is basic evapotranspiration which is generally a day/light requiring process.

Or nighttime process if the concentration around the roots is higher?
In the evolutionary scheme of things I'm not ready to accept that orchids follow the basic evapotranspiration method. (They are special )

Orchids are not different from other household plants like philodendrons that you can stick into water (like in a hydro or semihydro sytem) and have the roots become totally submerged, and still uptake nutrients by either osmotic or evapotranspiration mechanisms. There are also active transport mechanisms that generally require an exchange of one chemical for another at the root surface for uptake into the plant.

But orchid roots are different. Even though the grow side by side Philiodendron are more adaptable. You can take a philodendron stem with roots and put it in water and the roots continue to grow and live. You can't do that with orchid roots that have been air grown. Orchids will grow nes roots that adapt to being in water but they don't like it.

Think of your phrags that like to have "wet feet".

You kind of have me on this one!
But Phrags are special.
The wet feet lovers have evolved to grows in wet places and adapted their root systems. Try to grow a Phrag mounted on cork beside a Phal and it won't grow roots.....Unless the humidity is extreme.
As well Phrags that like wet feet and grow roots into the water also have roots above the water.

 

[Rick]

As far as we know! At least that is what science believes today. oke:

Osmosis is pretty basic stuff, even Shamans use the principal for decoctions and extractsoke:

Then why does a plant uptake too much potassium if it does not need (demand) it?

That one is an active transport mechanism. The bromeliad paper documented that one to a pretty good detail, but it happens in just about all plants. (orchids not special)

A lot of orchids grow with their root "uphill" so does this rule still apply? oke:

I was speaking figuratively about going against an osmotic gradient. But if salmon can make it upstream against strong current then I'm sure plants can defy gravity to move water uphill too. Redwood trees do a good job with this.

Or nighttime process if the concentration around the roots is higher?
In the evolutionary scheme of things I'm not ready to accept that orchids follow the basic evapotranspiration method. (They are special )

All plant life is special and gifted with basic sound principals to live by:wink:

But orchid roots are different. Even though the grow side by side Philiodendron are more adaptable. You can take a philodendron stem with roots and put it in water and the roots continue to grow and live. You can't do that with orchid roots that have been air grown. Orchids will grow nes roots that adapt to being in water but they don't like it.

Seems like the SH growers do it quite frequently with lots of orchid species.

You kind of have me on this one!
But Phrags are special.
The wet feet lovers have evolved to grows in wet places and adapted their root systems. Try to grow a Phrag mounted on cork beside a Phal and it won't grow roots.....Unless the humidity is extreme.
As well Phrags that like wet feet and grow roots into the water also have roots above the water.

Actually I'm getting pretty close to this in my GH. I set up a pearcei in a basket, and it ran roots all over the outside of the basket (the location was about 1ft away from some mounted phalaes). The long petaled species and kovachii are sending roots outside the baskets too. I have a lindenii and exstaminodium in baskets hung up next to a bark mounted Phalae fasciata and they run roots along the outside of the basket. Henryanum, and villosum seem to be pretty happy in mounted/basket systems, but they are pretty much epiphytes anyway.

 

[gonewild]

Osmosis is pretty basic stuff, even Shamans use the principal for decoctions and extractsoke:

That is what scientists say but not what a Shaman would say.

That one is an active transport mechanism. The bromeliad paper documented that one to a pretty good detail, but it happens in just about all plants. (orchids not special)

Orchids are too special. :fight:
Bromeliads are weird. They trap their water and eat frog poop.

I was speaking figuratively about going against an osmotic gradient. But if salmon can make it upstream against strong current then I'm sure plants can defy gravity to move water uphill too. Redwood trees do a good job with this.

Wonder why plants did not put their roots on top so they could take advantage of gravity?

All plant life is special and gifted with basic sound principals to live by:wink:

Some plants are Outlaws just like some people. They don't like rules.

Seems like the SH growers do it quite frequently with lots of orchid species.

The biggest problem people have when switching to S/H is the die off of old roots.

Actually I'm getting pretty close to this in my GH. I set up a pearcei in a basket, and it ran roots all over the outside of the basket (the location was about 1ft away from some mounted phalaes).

pearcei is one that does not like rules. It grows on rocks that get submerged during the rain season.

The long petaled species and kovachii are sending roots outside the baskets too.

If they only find nutrients in organic matter why would they grow out of it into the atmosphere?

I have a lindenii and exstaminodium in baskets hung up next to a bark mounted Phalae fasciata and they run roots along the outside of the basket. Henryanum, and villosum seem to be pretty happy in mounted/basket systems, but they are pretty much epiphytes anyway.[/QUOTE]

Once we know the secret they can all live together in harmony!

 

[keithrs]

Heres a besseae video... You may have seen it already.
Phrag besseae

 

[Rick]

Heres a besseae video... You may have seen it already.
Phrag besseae

Awesome Phrag tour!!