Plants Using Nitrite For Food?

[backtotropical]

Up until now, I thought I knew that plants use ammonia and nitrate as food, and have a distinct preference for ammonia. My understanding is that, for whatever reason, they don't use nitrite.

Upon reading Diana Walstad's 'Ecology of the Planted Aquarium', I notice that she quite clearly states that plants do use nitrite.

Now I'm confused. Can anyone confirm for me which is correct?

Cheers guys

BTT

 

[Mikaila31]

From what I under stand plants can absorb all three form of nitrogen. Ammonia, nitrite, and nitrate. But they do it in the order of Ammonia, nitrate, nitrite. So I plant will only start using nitrite if the water is lacking in ammonia and nitrate. If I remember correctly the reason for this is beacuse the nitrite ion is the most stable of the three, so it takes the most energy for the plant you utilize it.

[URL="http/www.aquabotanic.com/plants_and_biological_filtration.htm"]http/www.aquabotanic.com/plants_and_biol..._filtration.htm [/URL]

 

[Dave Spencer]

"While there is some scant evidence that plants will use a small amount of NO2-, it is generally a toxin anion that plays an insignificant role in our tanks after a period on new tank cycling. Try adding NO2- and see if the plants remove any significant amount. Try many species. The concentration levels will sit there unless you have bacteria to convert it to NO3-...."

Tom Barr

As far as I know, Tom is the only person that has tried this with many species.

With a calibrated test kit, it is something that we could easily test ourselves.

Dave.

 

[three-fingers]

I would think in nature, as Tom Barr mentioned, that bacteria are mainly the key, the bacteria living in the rhizosphere of the plants will convert nitrogen compounds to ones that plant can use.

In our tanks it would be filter bacteria, but it wouldn't be that important, since plants can presumably get to the ammonium first.

I have read posts on here that state plants prefer ammonium, nitrite and nitrate in that order, but don't think it's that simple as Diana Walstad's book, it seems to show that different species have different preferences as to weather they grow better with just ammonium, just nitrate or both.

A quick search on google scholar for "nitrite plant uptake" confirms that at least some plants can uptake it, though since not nearly is mentioned on nitrite uptake compared to ammonium or nitrate, I just assume it's not as important.

So, to summarise, it seems plants can use nitrite, but it's not talked about much because it's not that important to us.

 

[waterdrop]

Hi BTT,

When I read the 3 or 4 refs that Diana makes to Nitrite(NO2) in the book (and Note that Mikaila's link just refs a piece written by Diana which refs back to her book and some of other sources reffed in her book) I think in the end she and TB come out leaving us with pretty much the same info. There are a few bits in the scientific literature about a few species taking up NO2 under certain conditions but the literature and the reports of experiments are so few and far between that they don't seem definitive (per DW) and are dwarfed by more reports about ammonium and NO3 leaf uptake and a few growth experiments.

I think what Diana tries to do in her book is to jump pretty quickly to references to the literature as soon as she makes statements and she's the first to admit that there's just not much at all out there on NO2, either uptake or use for growth. She talks about nitrite uptake pretty directly (pp.22,23) but then just mentions it (pp.106-112) and switches right over to talking about NO3 in the more interesting later section where she talks about preferential uptake vs. best sources for growth.

LOL, I always have to struggle to remember when I get into this, that the context is just about the details of how plants get their Nitrogen, one of the 17 or so nutrients they need. Its interesting to think that Carbon gets top billing in the nutrient list, probably because its both hard to supply and because the plant needs so much of it. But a discussion like this reminds you that N is pretty tricky too when you try to get into what really might be happening and I guess the folks like Tom, Diana, Neil Frank and all of them who have done this for decades probably have stored up little stories in there minds for how plants take up and use each of many of the 17 nutritents.

I think the bottom line is that nitrite(NO2) is probably a minor player in a minor number of plants (and we also just don't know how many plants or to what extent because its either not out there or its too obscure or we are too inexperienced, lol) and since its a nasty toxin for our fish, its not going to be popular for having people (hobbyists anyway!) do many little "experiments" on.

Going back to why you started the thread, though, I think I know where you're coming from. Seems often like every simplification we try to use and repeat when helping each other and trying to help beginners is subject to being "wrong" when you get really technical about it or look at it in a different light!

~~waterdrop~~