Watering

[Stone]

Recently I've had to do a bunch of research on wild rice (Zanzinia) and commercial rice culture.

Wild rice germinates under water. In fact it germinates under ice sheet, under water under piles of old rotten dead stem from the previous growth season. Oxygen is 00000 at the seed and roots. The germinated plant grows like crazy (without oxygen) until it breaks surface, then it does induct oxygen backwards through the stem back to the root system for nocturnal respiration needs of the growing plant. However, the lack of soil oxygen is not relevant to successful growth, but the depth of anaerobic condition is. At low to no oxygen, low Oxidation Reduction Potential (ORP) conditions prevail. But if you develop strongly reducing conditions, from say sulfur reducing bacteria, methane producing bacteria, reduced iron... and really drive the ORP to low values then the rice seedling is unable to run a whole host of normal metabolic functions, and seedling dies.

In comparison to what low DO means for rice, the DO in an orchid pot with dripping damp potting media is nowhere near 0. Until you achieve "septic" conditions under SH conditions there is still DO in that water.

I've done a lot with manipulating ORP in both oxic and anaerobic systems to modify microfloral community structure, and there are significant differences when you do that. But I really think we are pushing into very complex systems at a very rudimentary level of understanding to really make a significant difference in how we grow orchids.

What do you mean by DO ?

 

[Rick]

Dissolved Oxygen.

Not sure if we've drifted off the original question of this thread, but what is the chemistry of the water you use for irrigation?

Is it pure distilled or RO?

Is it possible that the root growth is a response to increase in water or increase in a chemical in your water?

For years I watered (between weekly fertilizing) with straight RO. I believed in the notion that orchids were "salt sensitive" and my well water was very hard in mineral composition.

About 2 years ago I started adding a dash of Epsom salts periodically to my RO irrigation water, and shortly thereafter adding 10% of my crusty@%#! well water back into my RO water for regular irrigation. Growth rate, root production, and leaf color and substance improved dramatically. Reducing K in the fertilizer even more so.

Unless you are using pure water, could your plants be responding to increase in soluble Ca, Mg, and Silicates? Are you diluting out K buildup in the potting mix or offsetting a poor Ca/K ratio with increased amounts of your dilution water?

You might try an experiment with side by side groups of seedlings and water (with your present schedule) using your present irrigation water, and the same thing with straight RO (I'm assuming you may not be doing this already).

 

[Stone]

Dissolved Oxygen.

Not sure if we've drifted off the original question of this thread, but what is the chemistry of the water you use for irrigation?

Is it pure distilled or RO?

Is it possible that the root growth is a response to increase in water or increase in a chemical in your water?

For years I watered (between weekly fertilizing) with straight RO. I believed in the notion that orchids were "salt sensitive" and my well water was very hard in mineral composition.

About 2 years ago I started adding a dash of Epsom salts periodically to my RO irrigation water, and shortly thereafter adding 10% of my crusty@%#! well water back into my RO water for regular irrigation. Growth rate, root production, and leaf color and substance improved dramatically. Reducing K in the fertilizer even more so.

Unless you are using pure water, could your plants be responding to increase in soluble Ca, Mg, and Silicates? Are you diluting out K buildup in the potting mix or offsetting a poor Ca/K ratio with increased amounts of your dilution water?

You might try an experiment with side by side groups of seedlings and water (with your present schedule) using your present irrigation water, and the same thing with straight RO (I'm assuming you may not be doing this already).

I'm using 100% rainwater. I used Town water for years before I moved. It was horrible stuff. ph was about 10 and it left terrible calcium deposits on everything including leaves. Now with the rainwater, everything is perfectly clean and growing well.
I'm very wary of going back to mains water even though it's much better here. I have been adding very low levels of Cal.Nitrate after flushing and aside from regular feeding trying to keep on top of that K problem. (I've read
there's enough K in most barks to last a year without adding any extra!)
Along with a little Extra Mg and the occasional sprinkle of steamed bone meal , I figure I should have a reasonable N/K/Ca/Mg ratio.

 

[Rick]

Maybe going back to the original question of... does heavy watering after extended dry promote root growth (assuming that there is nothing in the water)...... I was looking around my GH this morning, and realized the amount of root growth (and new leaves/shoots) in the last couple months has been moving along at a much better rate than during the summer months.


However, because it is getting cooler and light duration reducing, I have been reducing both water and feeding since the middle of September. Not by a lot, so actual pot/basket moisture levels are probably not appreciably different.

I think others (at least working in GH's) have noticed a burst of activity after the hot summer doldrums. Can't say that it was attributed to increase in watering.

Usually a lot of paph growers will curtail watering somewhat anyway for cool periods, and wait for activity to start again in the spring before turning up the juice with more water and food.

But this could be the chicken / egg question. Does watering cause root growth or does increase in root growth induce growers to water more?


Since bark/CHC/moss, and other plant products contain all of our favorite goodies (without supplemental feeding). Is it also possible that by letting the material go through some dry/wet cycles, that you solublize nutirients that would otherwise be difficult to pull out of the cellulose?

Or did we cover all this already??

 

[Rick]

5 pages back you asked if you where watering correctly.

I guess the answer is yes if you are satisfied with the survival and growth rate of your plants.

Also if your survival to blooming size is pushing 100% and blooming is generally achieved by 5 years out of flask, then I'd say you have nothing to complain about comparing to just about the best of us.

There's a few speices I could claim that for, but looking around and comparing what others do (exactling what you are doing now) is how I improved the results for the species that didn't make the above cut.

The above was the reason that got me fixated on the low K stuff. I've filtered all the anecdotal info from questions I've asked on this site, tracked my own half baked experiments, and reviewed the field research and agri literature. Kind of like a giant mental ANOVA.

 

[Stone]

When I think about it, my observations were really more directed towards the parvis and brachys that I'm inerested in at the moment. Not so much the Indonesian sp. which seem to like more water and heat generally. Just looking at the leaf structure ( more succulent, leathery, harder and smaller ) indicates to me that they come from more extreme type environments and need to be able to survive periods without rainfall. at least more so than the soft leaved types. Maybe they have a greater sensitivity to periodic water.
Or maybe I'm just pinpricking.
All we can do is try to keep learning.
I have lots more subjects I'd like to disscuss.... temperature.......air...............light.........................individual sp......etc....etc

 

[Rick]

When I think about it, my observations were really more directed towards the parvis and brachys that I'm inerested in at the moment.

Then for sure, you really need to get Averyanov's book for all the climate and natural history details for parvis.

At least from my perspective, the brachys are a bit different. Most (bellatulum seems to be the exception) are found relatively close to the ocean. Some are found within salt water spray range of the ocean.

Have you seen any of the insitu pics of niveum (and leucochilum too I believe) growing sympatrically with exul on limestone cliffs just above the waves?

Having them so close to salt water should dispel the myth that they are sensitive to salts.

However, that does not mean that they are insensitive to ionic imbalance. Saltwater fish and inverts will die (in less than 48 hours) in saltwater composed only of NaCl. It needs to have the correct ratios of Mg, Ca, and K along with the Na to provide a suitable environment (I've done this test in my lab several times to verify this). Natural saltwater is only about 2/3's NaCl. The next most abundant salt is Mag Sulfate, followed by Calcium salts, with Potassium salts a close 4th.

Then if you add the fact that they grow on limestone cliffs, you start to put together a picture that Na may be irrelevant as long as there's a ton of Ca and Mg around.

Bellatulum may be the only brachy that is strictly inland (concolor ranges widely, but apparently also has seaside populations), but it is also found in close association with limestone.

 

[Stone]

One of our club members showed us a picture of niveum growing in basically full sun on what looked like bare rock with no moss or leaf-litter to be seen but a straggly shrub growing above it for midday shade. They were just meters from the ocean. These are tough plants!

Aren't Na ions easily replaced by Ca ions? We were told apply Gypsum to improve sodic soils as Ca is more tightly held than Na.
I'm basically treating my concolor like bellatulums.

 

[Rick]

One of our club members showed us a picture of niveum growing in basically full sun on what looked like bare rock with no moss or leaf-litter to be seen but a straggly shrub growing above it for midday shade. They were just meters from the ocean. These are tough plants!

Aren't Na ions easily replaced by Ca ions? We were told apply Gypsum to improve sodic soils as Ca is more tightly held than Na.
I'm basically treating my concolor like bellatulums.

Ion exchange is a two way street. Especially if the attraction is moderately low. What can go in can often be reversed with a high enough concentration of the opposing ion. In your bark, moss or CHC mixes, the preference is actually to retain the monovalents (Na and K)but you can force them out (and keep them out) with a good dose of divalent ions (Ca and Mg).

But if you don't keep up the maintenance of the Mg and/or Ca then these can be replaced out again by the monovalents.

My speculation is that this is one big reason everyone is seeing so much improvement switching to the Orchiata products while still using a fairly high dose of K in their fert mix.

As you've noted there may be very little soil around niveum roots anyway. So the cation exchange issue may not be important for wild plants as opposed to the imbalance of ions sucked up by the plant. Using the marine organism example I gave, the uptake of salts is not a passive act based strictly on the relative amounts of the ions in the environment. There is a selection going on, but the organism is also working with the whole matrix to help push and pull the ions into its system.

 

[cnycharles]

one thought about plants that are growing near the ocean and get spray, is that even though they may be near sodium, they are likely always wet with oxygenated water. often when my plants get burn it's because the salts get high when they dry out. near the ocean, they may be getting 'leached' all the time sort of so to speak

 

[paphioboy]

I posted a thread on exul and brachys in-situ here:

http://www.slippertalk.com/forum/showthread.php?t=19064&highlight=exul+in-situ

 

[gonewild]

one thought about plants that are growing near the ocean and get spray, is that even though they may be near sodium, they are likely always wet with oxygenated water. often when my plants get burn it's because the salts get high when they dry out. near the ocean, they may be getting 'leached' all the time sort of so to speak

Yes. And anything near the ocean is damp at night. So the roots on these plants are probably never dry for long.
Where the plants grow near the ocean spray how often does it rain?

 

[Rick]

Yes. And anything near the ocean is damp at night. So the roots on these plants are probably never dry for long.
Where the plants grow near the ocean spray how often does it rain?

According too Birk, the rainy season lasts from somewhere around May and tapers of in November. And then its supposed to be real dry (during Northern hemisphere winter months).

 

[Rick]

Had a friend that lived on Toes beach in LA. House was 100 or so yards from the water. Pretty much any unfinished metal (car frames, bike parts....) would rust away at a much faster rate than anything at my house (about 10 miles from the waves). The regular fogs also seemed to conduct the salt spray even when the wind was light.

I really don't think it makes that much different if conditions are damp or dry with regards to salt overload in the plants, but rather the balance of the different ions.

The marine organisms I referred to are constantly immersed in water, but fatality is assured if there is no Ca/Mg/K to go with all the NaCl

The salts are going to go into the plants wet or dry.