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...
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...
