Silicon and its role for plant health
In my professional life I have frequent contacts with scholars and scientists working with metallurgical and inorganic chemistry. Sometimes I even stumble into fields that are closer to my passion, orchid growing. A few days ago I had the pleasure to meet a prominent professor of the Russian Academy of Science that has spent the last 25 years investigating silicons role in plant nutrition. He showed us results from silicon fertilisation in Russia, China, Australia, USA covering a range of crops and results. Some of these tests were performed on large crops, like 5000 hectars of sugar-cane, citrus plantations in Florida, rice in China etc. Most of the results focused on the fact that silicon fertilisation improved the plants resistance to stresses. There are basically two ways it may happen, i) by improving the plants armour and ii) by improving the plants internal "pesticide production". The first is easy to understand and has been known for many years, the latter is a bit more "chemical" in nature.
To fight stresses (like attacs by fungii or insects) the plants synthesise a range of chemical compounds, that can be non-specific antioxidants or stress-proteins. The latter being "targeted" towards particular stresses like e.g. insect attacs. The role of the silica is as catalyst for the production of these compounds. Silica gel is a well-known catalyst in many types of syntheses in organic chemistry. By depriving the plant of silicon, the immune system suffers and they not only get more prone to infections, but also less able to stop the infection. BUT they grow, and if kept free of infections, nothing is noticed. And if they get an infection, well we all knows about those lethal erwinia/phytophora etc. infections...
This link is to an essay that sums up many of these things, although more has become known the last 3-4 years (the paper was written in 2009)
http://www.nutricaodeplantas.agr.br/site/downloads/unesp_jaboticabal/epistein_ann_appl_biol.pdf
Some you you may have noticed my scepticism to using alkali-silicate solutions as silicon fertiliser. The reason is that in those solutions the silicon is present as polysilicic acid which is not absorbed in an efficient way by the plants. The silicon should be as monosilicic acid that can be obtained by solution of silicates and amorphous silicon dioxide. DE is one the most common silicon fertiliser and is used in large quantities in sugar-cane fields in Australia. In Japan slags (mainly calcium silicate) are much used as silicon fertiliser. The silicates have a liming effect so should not be used in orchid composts. DE should not influence pH much and should be ok for orchids.
B
In my professional life I have frequent contacts with scholars and scientists working with metallurgical and inorganic chemistry. Sometimes I even stumble into fields that are closer to my passion, orchid growing. A few days ago I had the pleasure to meet a prominent professor of the Russian Academy of Science that has spent the last 25 years investigating silicons role in plant nutrition. He showed us results from silicon fertilisation in Russia, China, Australia, USA covering a range of crops and results. Some of these tests were performed on large crops, like 5000 hectars of sugar-cane, citrus plantations in Florida, rice in China etc. Most of the results focused on the fact that silicon fertilisation improved the plants resistance to stresses. There are basically two ways it may happen, i) by improving the plants armour and ii) by improving the plants internal "pesticide production". The first is easy to understand and has been known for many years, the latter is a bit more "chemical" in nature.
To fight stresses (like attacs by fungii or insects) the plants synthesise a range of chemical compounds, that can be non-specific antioxidants or stress-proteins. The latter being "targeted" towards particular stresses like e.g. insect attacs. The role of the silica is as catalyst for the production of these compounds. Silica gel is a well-known catalyst in many types of syntheses in organic chemistry. By depriving the plant of silicon, the immune system suffers and they not only get more prone to infections, but also less able to stop the infection. BUT they grow, and if kept free of infections, nothing is noticed. And if they get an infection, well we all knows about those lethal erwinia/phytophora etc. infections...
This link is to an essay that sums up many of these things, although more has become known the last 3-4 years (the paper was written in 2009)
http://www.nutricaodeplantas.agr.br/site/downloads/unesp_jaboticabal/epistein_ann_appl_biol.pdf
Some you you may have noticed my scepticism to using alkali-silicate solutions as silicon fertiliser. The reason is that in those solutions the silicon is present as polysilicic acid which is not absorbed in an efficient way by the plants. The silicon should be as monosilicic acid that can be obtained by solution of silicates and amorphous silicon dioxide. DE is one the most common silicon fertiliser and is used in large quantities in sugar-cane fields in Australia. In Japan slags (mainly calcium silicate) are much used as silicon fertiliser. The silicates have a liming effect so should not be used in orchid composts. DE should not influence pH much and should be ok for orchids.
B
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