The aaplication of Hoagland was for hydroponics whereas MS was for gel media.  Leaf analysis can be specific for MS inorganic and organic components, but H is formulated without organics for root absorption in non sterile conditions.

The aaplication of Hoagland was for hydroponics whereas MS was for gel media.  Leaf analysis can be specific for MS inorganic and organic components, but H is formulated without organics for root absorption in non sterile conditions.

I was thinking about that distinction, but we grow also Arabidopsis in Erlenmayer flasks in liquid medium. Or is that somehow different from hydropony?

(because of the length of incubation?)

Hoagland medium has got no organics nor sucrose but essential elements. Hydroponics is a supply of elements in water and requires rooted plants and water flow around roots and is applied in greenhouses

Look like that Hoagland solution is not only used for hydroponics. It is also made into plant tissue culture medium for specific plant species and purposes. Commercial companies sell them.

1. See: Hoagland’s No. 2 Basal Salt Mixture

(a) http://www.sigmaaldrich.com/catalog/product/sigma/h2395?lang=en®ion=US

(b) http://www.sigmaaldrich.com/technical-documents/protocols/biology/classic-plant-media.html

2. Attached article: Hoagland & Knop Medium 

See the results of two plant species cultured on this medium.                                                                                  

HK is not H, but the rationale is anlyse a leaf composition for ions sugars  amminoacids and pH in order develop a suitable medium for a species. MS was from tobacco leaves. H followed the early introduction of hydroponics.

A little history of Hoagland solution and Hoagland & Knop Medium:

 A part from the attach article.

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The First Scientifically Designed Hydroponic Solution:

The original formula for hydroponic growing that is still followed in principal today was conceived before World War 2, way back in 1938 by two scientists named Hoagland and Arnon. Dennis Hoagland was working as a plant nutritionist at the University of California Berkley from 1927 until 1949, and was a member of the National Academy of Sciences and a specialist in hydroponics. His formula has been called "Hoagland’s Solution" ever since. But the original formula was modified by Daniel Arnon in 1950 to include chelated micronutrients, and since 1950 it became the standardized nutrient solution used in hydroponics, whether it was by scientists or horticulturists. This liquid formula has been copied since the 1950’s as it is chemically stable when made as 4-part concentrates.

Dennis Hoagland developed this formula by studying the amounts of mineral nutrients found inside the cells of healthy tobacco plants. From this data he developed a soil free, water-based way of growing plants that provides nutrients in the same amounts found inside healthy, living plant tissues. All species of plants grow well with Hoagland’s solution, and scientists still use this formula to cultivate plants experimentally. Hoagland’s work is being replicated today by modern manufacturers to make concentrates for plant growers.

Hydroponics in Science and Horticulture:

So since 1950 scientists have clearly defined the chemically stable formulas necessary to create concentrated stock solutions that are ideal for all kinds of plants and growing methods. Soil based farming and petri-plate experiments on plants will succeed equally well when the plants receive Hoagland’s fertigation solution derived from 4-part concentrates. This is a blueprint formula to copy, you simply cannot combine concentrated plant nutrients in water many other ways and avoid cross-reactions.

In the scientific setting when growing plants experimentally via tissue culture in petri-plates with a sterile agar (gel) medium, one can use a product called "Hoagland Knop Medium" made by Plantigen Himedia; this dry powder is a blend of all the mineral nutrients in Hoagland’s solution plus the agar gel used to grow plant cells in-vitro. Scientists today still use Hoagland’s recipe, and so do the manufacturers of liquid fertilizers for cannabis. This is the base line from which all modern liquid concentrates are formulated.

The ingredients in Hoagland’s solution are the mineral salts that dissolve in water to yield the 12 essential elements as ions to plant roots (ions are electrically charged atoms and molecules). The amounts of each nutrient in Hoagland’s formula are the minimum ppm needed of each element for healthy plant growth to occur. Hoagland’s formula is intended to deliver plant nutrients in solution at the following rates:

Macro and secondary nutrients.

• N 210 ppm

• K 235 ppm

• Ca 200 ppm

• P 31 ppm

• S 64 ppm

• Mg 48 ppm

Micronutrients:

• B 0.5 ppm

• Fe 1 to 5 ppm

• Mn 0.5 ppm

• Zn 0.05 ppm

• Cu 0.02 ppm

• Mo 0.01 ppm

Hoagland devised 4 stock solutions to use as concentrates for plants he grew hydroponically. These are combined in diluted form to produce the final fertigation solution with the amounts of each element shown above. They were mixed into water to create one standard nutrient solution.

Hoagland’s solution was not designed to be applied in different ratios, such as a "veg" or "bloom" fertilizer, one standard dilution was good for all plants. The 4-part stock solutions were conceived to prevent the chemicals involved from cross reacting to produce insoluble precipitates, and when mixed the same way they created a reliable and constant fertilizer solution. This link describes the preparation of Hoagland’s concentrates;

http://prometheuswiki.publish.csiro.au/tiki-index.php?page=Hoagland%27s+nutrient+solution