Multipart thread, mineral nutrition of Paphiopedilum

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Jun 10, 2006
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I will start to type something quite long, result of my knowledge in paphs requirement and potting mix interactions, as well as knowledge gained from tissue culture. A bit of history in that first part.

First, plant nutrition is never, ever, an exact science. It will forever be impossible to study the activity of K+, NO3- or whatever ion "alone". Increasing or decrasing an ion in a solution will always interfere with the general composition of the solution, including the pH of that solution before and during plant use...

Let's take an example, to study the effect of an increase of K+ in a nutrient solution at pH5.7.

If you want to supply this ion, you have to supply a salt. KCl, potassium chloride, KOH, potassium hydroxide, or K2SO4 potassium sulfate, KNO3 potassium nitrate. Therefore if you increase K+, you add or increase in the solution the concentration of another ion. K+ is a cation (+) Cl- is an anion (-). Increase K+, and you add chlorine to the solution, or, with the use of KOH, you increase the pH very heavily. If you want to lower the pH increased with the use of KOH, you have to use an acid, that will add another ion in the solution. If you decide to leave the pH of the solution go up, and simply study K+, then you may induce a deficiency or precipitation of other ions...

Mineral nutrition of the plants has to be studied in "batches". It is what makes it so complicated. In the horticulture industry, most of the time the concentration and type of the fertilizers are studied, 20-20-20 at 0.5, 1, and 2 g/L vs. 28-14-14 at 0.5, 1, and 2g/L mixed with calcium nitrate and magnesium nitrate, at the same rate or various rates as an example, and see what performs the best. The interaction with the potting mix will be tested. Foliar analysis are conduced, and some salts can be added to correct a deficiency here and there, according to the "industry standard". Yet, people who have dogs know that chocolate can be deadly, and cats require in their diet some specific aminoacids to perform and survive well.

Orchids, apart from a couple commercial hybrids, are poorly understood, and scientist, to make very simple, simply assume that they have requirements that will fit the general grids used for many plants. In fact, specialists know for sure that certain species and group of species react very badly to some nutrients. Some Australian plants can be quickly killed by a single 10-52-10 application, because they cannot stand of phosphorus. Some alpine cushion plants will be stunted if they are not supplied with certain types of heavy metals ( usually found in their serpentine habitat).

I have been growing paphs for a long time, and had trouble to understand why certain groups of species are short lived in cultivation, unless luck is taken into account. Paph violascens, bougainvilleanum, sanderianum, randsii, are such "short lived" plants. Occasionnally an individual plant or two will perform very well, or sometimes all the plant in a given location, but that's nothing close to science. Many bacterial rot, root losses, etc... are recorded, and many, many plants end up in the dustbin at the end.

I started asking for foliar analysis in the 90's. Sometimes, the plants would perform badly, but be in the "standard" according to the analysis grid. Therefore I would ask a lot of exotic analysis, molybdenum, unreduced nitrate, nickel, boron, cobalt. I would make a similar analysis with a very healthy wild collected plant too, to make comparison. And the conclusion was pretty stunning: always there was a reason for a plant/group of plant demise.

At the same time, I started to make a lot of flasks. Some of the earlier formulations actually include urea as a nitrogen source, sometimes alone. There was an article written a very long time ago by Joseph Arditti in the Botanical Review, 'factors affecting the germination of orchids seeds', that he presented to me in 1993. The tree trunk effluate, coralorrhiza seeds analysis, and some others factores puzzled me a lot, as they were completely out of range according to the common knowledge of plant nutrition requirement, but completely accurate according to my foliar analysis of wild plants... Thanks to that small book, I could progress very quickly.

First, the ratio Fe:Mn:Zn. In the fertilizer industry, that ratio is usually from 4:2:1 to 4:4:1. In the foliar analysis of healthy and wild collected plants, I got very frequently a ratio of 1:8:4 to 1:8:8... Not exactly something the fertilizers can supply. I did not understand though how some plants were looking that beautiful in cultivation, except a note about the "greening effect" of dithane ( mancozeb) on some crops. I do not remember where I read that one, but anyway, a spray of dithane monthly made very, very beautiful plants. Most professionnal growers used dithane at that time. Since those old days, most switched to more "powerful" fungicides, creating a nutrient deficiency in their plants...

The old firm of Vacherot & Lecoufle ( now down to low standard unfortunately...) was using Kocide 101 at very, very full strenght sprays weekly, including dendrobium, miltoniopsis. Apart from that they used tap water, very hard ( I remember an EC of 800 before adding the fertilizer) + nitric acid to bring down the pH7.8 to 5.7, and addition of 1g/L of fertilizer (nitrogen source, only ammonium...). They had really great, gorgeous plants, and no sicknesses.

Then, I was amazed at how cattleya seedlings in flasks would grow when grown with urea only, and a bit of peptone. Definitely much faster than when NO3- or NH4+ were used. I tried cold filtration of urea added to the sterile media, and the effects were always impressive and immediate. Floricultura in the Netherlands and the Eric Young Orchid Foundation told me that they were using high urea fertilizers to get beautiful plants. According to Alan Moon, it was even absolutely required for some genus...

After those "discoveries", I soon realized that there was a lot to learn about orchid and paphiopedilum nutrition. That's why I started to experiment, in flasks first with Gelrite ( more "inert" than straight agar, that can contain micronutrients and many impurities...), then on plants, completing my knowledge with analysis of soil, plants, potting mix, and growing/stunted plants. I will share progressively my findings ( with foliar analysis for the scepticals) in this thread...
Hmmm, dithane provides manganese and kocide supplies copper? So your experiment is looking at these elements?

Interesting information. I was wondering when I was doing some reading this morning about seaweed having the right amount or proportions of manganese and zinc? The article I was reading about kelp extracts said that they had both elements in it but don't know how much they might have, though different seaweed extracts probably aren't created equally. Also was reading about fulvic acid and it's ability to take minerals present but not readily available and taking them into solution and greatly benefitting plant growth. Is this something that could be helpful to the species you mention (and others) without having to use a fungicide? I'm always looking for a way to not have to put on spray equipment...
Based solely upon what has been presented so far, this is going to be really good, and should probably be published as-a-whole somewhere.

An interesting observation about the kelp extracts, Charles. It's also quite interesting that urea - which we all have been taught cannot be used by orchids - had such an effect. I love it.
OK, part 2 on the soon way hehe...

Just to reply to some questions over there before jumping to the next section.

10-52-10 has been used by many growers, including AnTec, and I still use it on all of my orchids and plants. It has absolutely no "bloom booster effect", despite some claims that high-P fertilizers can achieve such a result.

I use it in 3 ways, one to promote rooting after repotting, I use it for 1 month nonstop at 0.5g/L. It has wonderful effect on any kind of orchids. The second, as a routine schedule for paphs, about once monthly to once every 6 weeks, same rate. The third, I use it as my MAJOR fertilizer for the parvis, delenatii, armeniacum, micranthum and malipoense ( don't do that on emersonii or hangianum, or they will look really, really funny !).

About the Kocide observation. Of course it supplies some copper, but the main, key point, is that high pH + micronutrients does not cause a toxicity in paphs at all, and the plants are able to take up what they require, even if the copper ions are found at the root system level ( where kocide ends up sooner or later) with an acidic pH. I will explain why it is so important later.

Kelp extracts and such compounds. There is a product in England called "Maxicrop" which is exactly that, a buffered kelp extract. It was used heavily by the Eric Young, and maybe is still used, whether in rockwhool or other mixes ( a funny note, the EYOF always killed their complex paphs in rockwhool, that's why they had to use bark for them but the largest complex paph grower in the Netherlands use insulation rockwhool as a potting mix...). I have seen, and used myself as a flasking mix. One flasking service in England used to use Maxicrop, 10g sugar, 0.5g Calcium nitrate and 3g/L Gelrite, byebye. They were doing wonderful paphs flasks with that...

I type part II now...
An interesting observation about the kelp extracts, Charles. It's also quite interesting that urea - which we all have been taught cannot be used by orchids - had such an effect. I love it.

In that article I was reading the other morning, they also talked about using hydrozyme or hygrozyme and it was also one of the tests that had good results. I stopped at one of the local hydroponic shops last night and got some, and the owner mentioned that another local orchid grower was using it and was very happy with it. Ray, (I know slight thread hijacking sorry) have you tried this, I will be soon and may end up being a great addition to the whole s/h approach. As soon as I can find some fulvic acid will try it on some of my orchids and non-orchid plants.

About our supposedly not being able to use urea (or not a great idea if they grow too quickly and weakly) more of my informal research if you want to call it that shows in so many cases if there is a big business somewhere that wants to make lots of money they will knock the really cheap way to do something well (expensive fertilizer instead of urea, many other things) then the cheap way will be attacked incessantly until nobody believes in it anymore. As another outside example I was just reading about oils for cooking and it turns out some of the best/stable ones that have been decried in the past for frying are palm oil and beef fat. All the highly processed high volume ones you find in stores are largely not good for you even if they aren't a 'trans-fat'. Hijacking aside, this is a very interesting thread and I await future installments with great interest!
I had of course some ideas that turned out to be wrong, and one of the main problem was to design something that is accurate for studying the behavior of paphs with given nutrient solutions.

A lot of problems were facing, and I found them out one by one later, only to restart again studying, studying... with the bank account going sharply down paying many analysis. A lot of questions.

The first idea, I wanted to study MINERAL NUTRITION, so I had to find an "inert" media right ?

I wanted to make it as "scientifical" as possible, but I soon realized that it is very complicated, if not nearly impossible. So I had to be as close as possible to that aim.

In fact, I discovered soon that, apart maybe from Teflon and glass beads ( acid washed please, to remove the production byproducts...), there is no really "inert" media. Rockwhool is on the alkaline side, and slowly attacked when watered with acidic water. All the porous stuff, whether clay, lavarock, perlite, would sooner or later capture ions, cristallize whatever, release others things... Bark, sphagnum, of course are far from inert.

In flasks, most agar have impurities ( in fact, one of the very best agar available, Daishin agar, has a lot of impurities, micronutrients, etc...). I decided to use Gelrite, but the bonds that make the matrix solid are made by divalent cations... Calcium and Magnesium. So an increase in those two ions would solve the problem. Unfortunately, that was plain... WRONG ! A trivalent cation can actually displace calcium, and be bound, therefore unavailable to the plant instantly after sterilization. As the plants grow up, they will dissolve the matrix somehow ( by acidifying their environment), and use calcium and magnesium that were the links. Studying calcium or magnesium accurately is therefore very difficult with the gelrite use.

After that, the other problem is "what analysis to order from a lab ???". Sounds a dumb question, but there are a lot of protocols to follow to make analysis.

I will give a simple example. Wash coconut coir with distilled water 50 times. Give it to a lab to analyse. Some will report no sodium, no potassium. Some will report very high figure, for the same batch. The reason is very simple.

The extraction before analysis is very important. One can make a water extract, acid extract, a destructive analysis ( everything is converted into ashes...), an alkali extract, a barium sulfate extract... etc... Discussing with the lab of Bas van Buuren, they informed that there were such problems with the foliar analysis. A plant can have a very high iron content, and be iron deficient. There is another parameter that I did not think about before ' availability'. Some ions can be in an unavailable form in the leaves, so a destructive analysis of the leaves would give a rate of iron as an example that is acceptable, but the plant is starving completely.

I was getting ready for a lot of headaches. Plus, I had to find "the" lab that would make everything I wanted. Most of the labs are used to work with large samples, and I wanted them to work with 50-100g of fresh leaves, not 2kg ( one lab asked me for that !!!). Then I needed to have a very accurate lab that could do the weird analysis, nickel, molybdenum, NO3 foliar content, some organics too, etc...

Apart from that, I wanted a pathology lab, and a soil analysis lab. I ended up with Bas van Buuren Lab for the soil, Wageningen Consulting for the path lab, and Green Control ( public joint venture of Wageningen) for the foliar analysis. They were very helpful, and I had ( I still have) to follow them all the time, to be able to compare what is going on. One very important thing, we are not bees, and we cannot fly from one lab to the other. Each lab has its specific protocols, normalized, and it is not guaranteed that 2 labs will have the very same results. On the other side, all the results of a very good lab are standardized against their own internal scale, therefore the results can be compared. I discussed the price, and the latest prices were 120 euros for the path lab if PCR was required, 30 euros/substrate analysis ( poor guys, they even had to analyze gooey agar... they are really helpful for that), and 60 euros/foliar analysis. All "complete".

The weirdos that I asked for ( and I know that, regarding orchids, I have been the only one to study those !!!) were nitrites (!), selenium, chromium, even mercury ( rockwhool has a very high content sometimes of lead and mercury...).

The pathology lab was included to detect pathogens if a chlorosis or unhealthy plant did not show any mineral problems.

The very early analysis that I asked for ( the "common ones" that everyone in the horticulture asks for) were completely useless, first because when they are incomplete, it is impossible to guess what is going on ( I will explain the interaction, but as an example, the total N content of a leaf is useless if one does not get the NO3 content and the Molybdenum content), and second, because they did not fit any "standard interpretation key" anywhere.

I still have that first analysis of very, very strong, "maybe wild collected" stonei that I imported from Sarawak with a CITES.

On dry matter :
In percent N 1.3. P 0.6, K 0.9, Ca 1.2, Mg 0.6
In ppm Cu 130, Mn 1823, Zn 636, Fe 116, B 50

Conclusion of the lab, the plants were in deep ****, because that analysis showed major deficiencies and toxicities. But the plants were gorgeous. I asked another lab to analyse others stonei, from a completely different source, fresh wild collected leaves from Bakun ( Sarawak). The resultats were nearly the same...

That's where I started my thinking that mineral nutrition of orchids is poorly understood, or even unknown. After that analysis I decided to make as many analysis as possible, and build up a database. I had at that time the idea that paphs can behave more or less as saprophytes for some of the species, or at least use some aminoacids and oligopeptids present around the roots.
just a thought based on how some people collect leaf samples: what if someone were to only take lower leaves as samples since they could take a healthy chunk and still leave part of the leaf, and as a result take leaves where nitrogen had started to migrate upwards up into the plant? the whole plant might look great but the tested leaves might be 'lacking' in nitrogen because of it's moving upwards or into other parts of the plant? also there could be a cycle where nitrogen is in leaves, and then when roots start to grow some may be taken out and moved to forming root tissue, or if it has recently flowered may be low in nutrients, or.... just some ideas.
Based solely upon what has been presented so far, this is going to be really good, and should probably be published as-a-whole somewhere.

An interesting observation about the kelp extracts, Charles. It's also quite interesting that urea - which we all have been taught cannot be used by orchids - had such an effect. I love it.

I think the crop plants that typically get urea based fertilizers use it through bacterial intermediaries (not directly). I'm sure orchids can use urea ammonia if appropriate soil bacteria are present. However, orchids are often kept in more inert and disturbed media where the populations of useful bacteria are unstable too.
Perhaps the passage from Julius Caeser that "and all our yesterdays have lighted fools the way to dusty death" is closer to the truth than we realize. I can't even begin to imagine the complexity of setting up experiments Sanderianum is contemplating to obtain meaningful data. Add to this the law of limiting factors and it completely boggles what mind I have left. Like you Ray, I have to laugh about the controversy concerning urea. Some years back Fred Bergman published a brief study in Phals involving urea vs non urea fertilizers and in short concluded that not only was the urea utilized, but produced more robust plants than non urea fertilizer. I felt the experiment was not well controlled but, until WR Grace took them over, perhaps more orchids were grown with the old Peters 30-10-10 than all other fertilizers combined.
Then I got hold of 2 very different species, Paphiopedilum mastersianum, and emersonii.

I had plants cultivated for a while, and "new" plants for mastersianum. The latter invariable are much healthier than the former ones as a rule. Mastersianum in the wild has very dark green, shiny leaves, and is a very fast grower. In cultivation the plants tends to become more on the yellowish side, and most die after some years of being chlorotic and necrotic. Only a very few mastersianum in the world survive more than 5 years in cultivation, one has to be realistic...

Emersonii has very dark green, shiny leaves, and grows very fast the first couple of months after import. Then it will progressively slows down, up to the point that the plant make a miniature shoot and collapse. The same stands true for hangianum. Most emersonii in cultivation died after some years, or at least showed considerable shrinkage.

I did not, at that time, realize the importance of a more detailed analysis, so I asked for an analysis with only a couple new parameters compared to the stonei analysis.

Let's start with the mastersianum. For accuracy, one has to take the same age leaves from all the plants, the general practice for orchids is to take leaf N°3-4 from the newest growing leaf. Then it is possible to have a way to compare the results all the time.

* Beautiful plants
In % : N 0.86 P 0.43 K 0.91 Mg 0.21 Ca 1.04 Na 0.11
In ppm : B 62 Zn 180 Cu 11.7 Mn 170 Fe 32 (!) Mo 11 NO3- 49.2

* Chlorotic plants ( still healthy but not as nice as the fresh ones)
In % : N 0.91 P 0.37 K 0.85 Mg 0.16 Ca 0.94 Na 0.08
In ppm : B 12 Zn 51 Cu 7 Mn 137 Fe 480 Mo 1 NO3- 293

All the elements expressent in % did not show anything really out of range between healthy and sick plants. Note that those figures are complete out or range if compared to any charts published for plants. Therefore I quickly found out that NO PLANT CHART can be applied "like that" to paphs ( and other orchids, I did not do only that work with paphs).

In the ppm, that was a different story. There were 3 main things

Boron level was quite low in the chlorotic plants, as was Zn
Fer was at too high level in the chlorotic plants.

And the most important: those damned plants were Molybdenum deficent !!! With a "standard" analysis, the results would show only a problem with Iron and Zn, maybe ( but yet, compared to standard charts, the figures are out of range, so one has to have analysis for healthy, clean plants). First Mo was lower in the yellowish plants, but the NO3- level was too high, showing clearly that Molybdenum deficiency. It is a very common diagnostic, but no one dared to study that on paphs...

That's one of the reasons I was very reluctant to use fertilizers with a high nitrate content to start with. I think that some people have chlorotic plants using MSU because of that molybdenum deficiency. Molybdenum is very trick as the ions containing molybdenum are easyli bound...

Emersonii ( the earlier imports from Viet Nam, beautiful green leaves, medium sized plants), leaves from freshly imported plants, untampered.

In % : N 0.98 P 0.18 K 0.97 Mg 0.26 Ca 0.98 Na 0.18
In ppm : B 128.8 Zn 236.1 Cu 10.8 Mn 831 Fe <5 Mo 17 NO3- 38.9

A lot of years later, the huonglanae ( like the one I pictured), fresh results :

In % : N 1.02 P 0.31 K 1.01 Mg 0.31 Ca 0.91 Na 0.26
In ppm : B 96 Zn 219 Cu 18.1 Mn 1318 Fe 14 Mo 15 NO3- 61.6

( some results omitted for huonglanae, I will write more on the additionnal parameters later...)

WOW !!! By all the horticulture standard those plants are... DEAD !!! Such high boron levels are deadly to many crops. The iron was below detection limit the first time, and years later, only 14 ppm. The sodium is about 25% the potassium content, The ratio N:K:Ca is 1:1:1 nearly. Well, such plants cannot live. Even the lab director when he got hold of the results for the earlier emersonii analysis provided me with another additionnal analysis free, because he said looking at those dark green leaves, it is impossible to obtain such results... Results were the same.

That's one of the reasons I started to understand that many people pompously speak about "plant physiology", but they would be totally inapt to explain such results... I suspect there are a lot of plants that have analysis complete haywire compared to the common standards.

We can note however, from those 3 very different species, some general trends that seemed at that time to be common to all paph species.
Another note about how the analysis were done. The leaves were cleaned with citric acid several times, and rinsed with pure water.

The preparation was made by crushing at 300 microns the samples
Dry weight was measured by heating to 105°C in an over ( got the specifications brand and type of oven...)
N total was calculated using the Dumas way.
P, K, Ca, Mg, Na, Fe, Mn, Cu, Zn, B. Mineralization dry state, use of HF, Plasma emission analysis ICP-AES
Cr, Cd, Co, Ni, Pb Mineralization dry state, use of HF, measurement by Atomic Absorption AET-AAS
Hg, 900°C under O2, concentration and reduction of Hg vapors, measurement in cold vapors by atomic absorption
S, nitro-perchloric mneralization, and ICP-AES
NO3, extraction hot water, transformation in NO2 and colorimetric measurement.

A few other analysis will be mentioned later...

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