Redness and Nitrates

[Allen_1971]

I was poking around in another forum and I noticed an interesting discussion going on about the redness of plants and the level of nitrates. Basically they mentioned that the low level of nitrates (<5ppm) in the tank seemed to influence the redness of their plants. So I was wondering, is there any truth to this? Does anyone have any experience?

For myself, I can only comment that my plants are very red, and my nitrates are very low (zero without KNO3). SO I can't dispute the discussion. Or course other factors like light and iron also play a part, but lets assume (for the sake of discussion) that they remain constant...

[vinz]

Errrmmmm... I deduce from your post that low NO3 => more red?

Well, both my planted tanks are low in NO3 at the moment and the new leaves of H. Polysperma 'Rosenervig' is redder then I've ever seen them. I still think lights make a diff. It's only new growth nearer the lights that show the redness. I getting chlorosis on some of the new growth too, which implies Fe deficiency normally.

Got the URL?

[Allen_1971]

yes... what they were saying that when their NO3 was low, the plants were redder. When the NO3 was high, the plants were not as red.

[vinz]

Something that just popped to mind... some of the companies that sell aquarium water quality products indicate that high NO3 inhibits plant growth. No numbers given though.

[toshi]

Lower N & P (leaner macros, save for K) generally equal redder growth... with some plants you can tweak the values of either N & P, or both. Some are less forgiving, i.e. Eusteralis stellata - but once you are adept at running a tank on the lean side you can easily compensate for situations where you've let it go too far. It soon becomes clear that red plants are very good indicator plants for N & P.

toshi - san francisco
Ludwigia brevipes!

[Allen_1971]

Toshi,

OK... but whats the mechanism for this? I mean why do lower macros impact the redness of plants. Do they become limited in their chlorophyll production?

Also, I read in a past issue of TAG that redness of plants was primarily due to (argh I forget the name) some chemical which plants use to protect themselves from intense light? Is there some correlation between this and the lower macros? for example, could the lower macros mean that plants are unable to photosythesize as efficiently, and as a result the intense light is more harmful and they produce more red pigments to protect themself (ok this is just my wild guess)...

[vinz]

anthocyanin?

[bclee]

If I don't remember wrong, higher P to lower N will produce redder plants.

BC

[toshi]

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On 1/7/2003 12:11:00 PM

Toshi,

OK... but whats the mechanism for this? I mean why do lower macros impact the redness of plants. Do they become limited in their chlorophyll production?

Also, I read in a past issue of TAG that redness of plants was primarily due to (argh I forget the name) some chemical which plants use to protect themselves from intense light? Is there some correlation between this and the lower macros? for example, could the lower macros mean that plants are unable to photosythesize as efficiently, and as a result the intense light is more harmful and they produce more red pigments to protect themself (ok this is just my wild guess)...
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I have heard the red response explained a few different ways, but generally I believe the accepted explanation (however vague) is that the plant is visibly showing stress due to leaner conditions (specifically N, P). Generally when stem plants show significantly more red, their leaves are smaller and not as lush or thick as they would be if the conditions were richer. They are also not as green.

toshi - san francisco
e-aquaria.com

[Allen_1971]

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On 1/7/2003 1:43:14 PM

anthocyanin?
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Vinz, I'll go back and check...

[Allen_1971]

OK I checked... its flavanoids.