# [Wet Thumb Forum]-Allelopathy in the planted aquarium



## flagg (Nov 29, 2004)

After re-reading Walstad's book during my extraordinarily long plane ride to Alaska, I began thinking about allelopathy and how certain plants, using allelopathic chemicals inhibit the growth of other plants as Diana describes in her book. As I was doing research on my herb garden this spring I read about certain terrestrial plants having _beneficial_ effects on other plants. For example, planting chamomille near an ailing plant will help that plant become healthy. Also, when growing herbs and vegetables, people frequently grow different plants together to either enhance each other's flavors or simply because they grow well together. Could these be examples of "beneficial (or reverse) allelopathy"? (Sorry, I don't know what the opposite of allelopathy is!) And, if so, are there instances of this type of "reverse allelopathy" among aquarium plants? Has anybody had experiences where two plants seem to enhance each other's growth or health? Diana, have you done (or do you (or anyone else) know of any) experiments in this vein? I don't know, it seems like, if terrestrial plants can do it, why not aquatic plants? Or perhaps I just had too much to think about on that 13 hour plane ride (or rather on those 7 and 3 hour plane rides w/ the 3 hour layover...)?

--ricardo


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## peter bradley (Oct 12, 2004)

I have found cryps planted as companion plant with the lace plant seems to benifit which is weird as they come from different regions maybe they carry a benifical fungi which helps the lace plant extact nutrients. I .hope your question generates more observations as it can only benifit all our knowledge peter bradley


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## dwalstad (Apr 14, 2006)

Allelochemicals released by plants in the aquarium can be expected to cause unexpected and unpredictable effects. I would expect that they could be beneficial or detrimental to nearby plants.

Allelopathy between plants is probably a minor factor in most aquariums. But one never knows...


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## flagg (Nov 29, 2004)

As if in answer to my question (and to expound on what Peter wrote previously) I found the following information at http://www.practicalfishkeeping.co.uk/pfk/pages/show_article.php?article_id=51

"I have planted Cryptocorynes around the Madagascan lace plant. This is one of the secrets of successful growing.

While Crypts are not found in the same region, they perform an important function. They are deep-rooted and not only keep the substrate sweet but also help provide extra bacterial growth essential to the tuber.

I've studied articles on the Madagascan lace plant and ones that were successful for a number of years were those planted in tanks with Crypts - hence the addition to my set up.

The plants have a symbiotic relationship and co-host fungi or bacteria necessary for survival and growth and absorption of nutrients. More research is necessary but how plants react together is a whole new science and may be the key to successful growing of some of the more difficult plants."

Kinda cool...

--ricardo


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## Miss Fishy (May 13, 2006)

I've noticed that nothing will grow well in dense clumps of _Eleocharis acicularis_ (Hairgrass). I thought it would look nice to have the Hairgrass mixed in with other small plants, but when the clumps get thick the other plants stop growing and often die. This only happens when Hairgrass is involved; mixed groups of other foreground plants grow happily together. Only rooted plants seem to be affected, so if it is due to allelochemicals, the Hairgrass must be releasing them into the soil. I have recently acquired another species of _Eleocharis_, so it will be interesting to see if the two can grow together and also whether the new species has the same effect on other plants.

A few months ago a tiny pond in a saucepan with some Java Moss and an Arum Lily growing in it was having trouble with slimy algae, so I threw some activated carbon into it, just to see what would happen. I did not remove any algae by hand or change any water. Within a week, the algae had died and the moss had started growing again! Could it be that allelochemicals from the algae were inhibiting the moss?

From Alex.


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## flagg (Nov 29, 2004)

Alex:

More interestingly (I think) is what effect did the carbon have on the algae that made it die out so quickly? By slimy algae do you mean blue-green algae? 

--ricardo


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## Miss Fishy (May 13, 2006)

Maybe the algae was only able to compete with the plants by using allelochemicals, and so when the carbon removed them, the plants were able to grow again and used up all the nutrients? The blue-green algae I had in one of my tanks was sticky and grew in sheets, whereas this stuff was just slime. It was slightly blue in colour, so I suppose you could call it blue-green algae too. 

From Alex.


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## flagg (Nov 29, 2004)

Interesting... I only ask if it was blue-gree algae because that is a bacteria not an algae so I was wondering if something else was coming into play considering...

--ricardo


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## dwalstad (Apr 14, 2006)

> Originally posted by Miss Fishy:
> I've noticed that nothing will grow well in dense clumps of _Eleocharis acicularis_ (Hairgrass). I thought it would look nice to have the Hairgrass mixed in with other small plants, but when the clumps get thick the other plants stop growing and often die. This only happens when Hairgrass is involved; mixed groups of other foreground plants grow happily together. Only rooted plants seem to be affected, so if it is due to allelochemicals, the Hairgrass must be releasing them into the soil. I have recently acquired another species of _Eleocharis_, so it will be interesting to see if the two can grow together and also whether the new species has the same effect on other plants.
> From Alex.


That's interesting what you've observed with the hairgrass. Eleocharis microcarpa and E. coloradoensis are two proven allelochemical producers (p. 37 and p. 45 my book). Scientists have actually documented the allelochemical-mediated inhibition of pond plants by E. coloradoensis.

The investigators chose to study the hairgrass because of field observations (like yours) that the hairgrass was inhibiting other, stronger plants.


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## MyraVan (Feb 13, 2005)

> Originally posted by rick6805:
> As if in answer to my question (and to expound on what Peter wrote previously) I found the following information at http://www.practicalfishkeeping.co.uk/pfk/pages/show_article.php?article_id=51


Not coincidentally, this article was written by one Peter Bradley, who is "the UK's leading writer on aquatic plants". Cool, nice to have another real expert contributing here,


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## flagg (Nov 29, 2004)

> Originally posted by MyraVan:
> 
> 
> > quote:Originally posted by rick6805:
> ...


Doh! I should have noticed that!


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## Miss Fishy (May 13, 2006)

Ricardo, this stuff was much less blue than what I would normally call blue-green algae, but it may still have been bacteria. It also could have been a combination of different algae and bacteria, like Diana describes on page 164 of her book.

Diana, the person that I got the new _Eleocharis_ species from, collected it from a local creek in the 1960s. I think it may be _E. pusilla_ as that is the only small Hairgrass native to this area. I planted it in two of my tanks 20 days ago, where it has taken off, sending runners deep into the substrate and growing many new leaves. In one tank I planted about 30 plants around a _Vallisneria spiralis_ runner which was growing very fast. It may be my imagination, but the Val's growth has slowed dramatically. The rest of the clump of Vals further away is still growing quickly.

From Alex.


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