Quote:
Originally Posted by dabblin-n-orchids
It is true that there are plenty of anaerobic bacteria and fungi that will rot the roots and roots that are not adapted to water will rot in a matter of weeks. But it appears that for some reason a thick layer of algae will prevent the growth of anaerobic bacteria and fungi. and if roots grow into water they grow noticeably differently and are adapted to being completely submerged and it would stand to reason that if you placed them in another media besides water they would die.
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Completely agree with the second point, but the orchids i have in water culture (well, roots that have escaped into the reservoir at least) do so in water that doesn't have
any algae, it gets cleaned regularly. I think algae might re-oxygenate the water, which is something that helps if you don't change the water regularly, but i haven't heard a reason to see why it would stop pathogens growing directly.
If there is an effect though, i think it might be that orchid roots need oxygen to produce their anti-fungal defenses. And when oxygen runs out in the water, the pathogens already in the water are able to attack the roots easier. Regularly replenished water, or water oxygenated through other means (including algae) might just keep roots healthy enough to resist pathogen attack, making it look like well-oxygenated water stops roots rotting. But that's just my theory.
I still agree that it's the specialised root structure in 'water' roots that somehow makes them able to survive submerged.
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