http://links.jstor.org/sici?sici=000...OR-enlargePage

Suggest adding Vit B12 might help germination of Najas(but not the other species).
Seed or propagules are not the same as plant cuttings etc.

Another classic mistake in interpreting the research is like this paper:
SpringerLink - Journal Article

Vitamin C(asorbic Acid), increases in response to stress.
People read this and think" If I add Vit C to the water, it's help my plants respond to stress!"

No, this paper does not say this at all.

Endogenous Vit C produced by the plant as an antioxidant is not the same as adding Vit C extogenously to water.

They are radically different issues and treatments.

Regards,
Tom Barr

Sorry for being slighly off topic here but Wetzel/Mc Gregor's statement in their paper on axenic culture and nutritional studies
about the ratio of monovalent:divalent cations seems interesting. The only other source I know of which claimed such impacts
has been a book from one guy called Hückstaedt some 40 or 50 years ago if I recall correctly.

Wetzel/McGregor found that by monovalent:divalent cation concentrations <1 growth in Najas flexilis was inhibited (in accord
with other prevailing unfavorable conditions).

Tom, do have any more info regarding this topic?

Thanks for replying,
Detlef

I think back then, 40-50 years ago, the whole mono/divalance things was "en vogue". Then came plant hormones, then molecular stuff and so on.

Plants and salt stress has come a long long way and we understand the molecular basis for a lot of it today. And that is what is occurring, salt stress, so when someone suggest that 20-30ppm of K+ inhibits something like Ca++ which is at 10ppm, I know it cannot be due this "ratio". Or even a ratio of 5ppm Ca++/ 50ppm K+, or 50ppm Ca++/ 5ppm K+.
such ratios in water are very different in the soil, they are far more concentrated in the soil pore water. Our concentrations are very dilute by comparison. We can also look at most any hydroponic solution, they are extremely rich by comparison.

Pretty simple test

Result: no influence was noted when the concentrations where kept near these amounts for aquatic plants.

I'll let you figure out your own conclusion and test these yourself from here.
These are not hard test to do with good methods and observe how things do with CO2 and aquarium plant species.

The vitamin issue is very speculative near as I can see for aquatic plants and actually "helping them". I've been unable to find much support for them. I do not think adding them hurt, however, but adding them does not help the plants as some seem to want to claim and put labels on their products claiming as much.

Saying it is "speculation and might work, or might not, but we added it in case it might work", is the way to do this. Otherwise these clowns marketing junk end up starting up some myth.

Most have no idea if they are right, or if it's applied correctly.
Maybe some do but do not care, it's their job to market and sell.
I do not know.

K+/Ca++ are another thread/topic.
I've covered various ratios and the +/++ charge issue a number of times.

Regards,
Tom Barr

It occurs to me that the term "vitamin" is probably misleading when applied to plants anyway. Are there any non-parasitic plants that require organic chemicals for growth?

Not that I am aware of.
Some algae though.
Not the types we see in our tank though.

Regards,
Tom Barr

Probably symbiotic algae, I'm guessing. Perhaps a natural version of one of those minimal-genome organisms like the one that Craig Venter is trying to build? Anyway, that's tangential.