Nelson Barbosa Machado Neto

Dear friends

Reading the forum about the tree fern fiber, some thoughts started to walk around my mind.
I am an agronomist and work with the genetics and physiology of the plants. I am also an orchid grower for 15 years although I have gone away from this activity for long time.
In my journeys into my country's woods, I could observe many orchids species which, always (except for the terrestrial and paludicole), have their roots exposed, that is, visible and many times covered with 'dust' as it is commonly said.
I start on this thought, if the orchids have part of the velamen covered with humus, it can't be completely harmful. I am thinking about meters and meters of confined roots inside pots, filled with tree fern fiber or any substrate which decomposes. Of course, the velamen will be covered by the humus, causing some oxygen deficiency to the radicular tissue and encouraging an anaerobe environment as it has already said.
Taking the word substrate into account, I think that it is just a support and doesn't help the nutrition. The nutrients to any cultivated orchid should be added periodically, as it happens in nature. The wind and the rain take charge of bringing those nutrients from other parts of the support to be intercepted by the spread roots of the epiphytic or rupicolous.
So, I should consider as a "bonus" any nutrient which can exists in any substrate, tree fern fiber, sphagnum, coconut bark, coxim, pebbles and much more.
The species preservation is a great subject which deserves and must be taken into account but I guess that it is not only the individual orchid growers who are using this fiber.
The big and medium greenhouses, Brazilian and foreigner, bear heavier responsibility than the small ones, although I don't have data to confirm this assertion (See the IBGE's site ).
I would like to think that the forum should discuss about the extinction of genetic stocks and species, even if it doesn't have commercial value at present. Species like Laelia alaori, Cattleya velutina and Cattleya kerri and some others which are showed in international catalogues as "exploited species until their virtual destruction, now available..."
Those facts should be considered instead of discussing the salts retention and quality of the substrates
The truth is that for the small orchid growers, the lack of a practical substrate will be an obstacle but I imagine for the big ones.
By the way, when will us discuss about the next to get in this list, the sphagnum???


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