Darkbluesky
Seedling
Hi
I have read a lot of discussions and information about the needed nutrients vs deficiencies in aquatic plants. Basically they need light, macronutrients, micros and carbon. But the relations, even reading opinions/tests of people around, are not too clear to me, for example:
Light. People say that light is just like a gas pedal in a car; it controls -mainly- the 'speed' of metabolism (growth).
AFAIK light never could be too much; following Liebig's law, the growth of the plant -with enough light- will be limited by the nutrient in smallest quantities (relative to the plant maximum possible uptake for each nutrient under given light, of course). In that case, with all needed nutrients present, but in small quantities in relation to light amount (at least 1 nutrient, or more), the plant should just grow fine (but -a priori- not slower than if we would have higher amounts of nutrients, for example to allow make use of the excess of light). I feel, though, that when there is low level of nutrients and high light, there is a slow down when nutrients get more and more scarce (more difficult to find them and maybe other metabolic reasons I ignore), so some slow down would be expected, depending on nutrient amount level under (and despite) high light. Nevertheless I think light is the first order driver for growth speed/metabolism, being secondary the nutrient level if really unbalanced.
In that case, we should not be causing any plant deficiency (thus, not DOC, NH4, etc leaking from plants leaves, etc). Do I understand it correctly? Have you experimented this?
Macro, Micros & Carbon. In the same way, as far as all of them are present (with enough light amount), the growth will be limited by the one more scarce (less available) for plant to uptake. Then deficiency will not be produced in that case, only growth could be hindered (slowed down or not, depending on light amount, read above and below).
So deficiency will be caused only if there is some nutrient lacking (not necessarily just in small quantities versus light amount, etc).
The exception to this would be the 'lower threshold' (I forgot now the technical term for this) of needed nutrients, which likely will vary for each plant type. I understand that even if all the nutrients (light included now) are available there is a minimum needed amount for the plant to be, at least, in vegetative growth (so they allow the plant to be alive although not actually growing). We would not like this vegetative status as I guess it is the line between plant (leaves, etc) leaching into the water column and don't, so better to have plants growing, even if it is at slow rate.
(Of course, I assume that plants do not leach if they grow, and they leach if do not (would it be because is unhealthy/deficient, or just simple vegetate). This binary understanding may not be completely true or is likely maybe too simple, though, but I never saw this very point discussed). My opinion is that the zone between very scarce nutrients and becoming deficient is a diffuse frontier, as the nutrients get more scarce and difficult to find the growth is slowed down (even in high light) and deficiency symptoms/leakages start happening even if there is some nutrient still available: it is not the same to find that needed atom 1 per second, than 1 per hour or 1 per week, where is the frontier between "slow down" and "stablished deficiency"?)
The problem of "not balanced" light vs nutrients, as far as I see it, is not that this balance has an inherent deficiency for the plants, but only that it is more likely for them to become deficient in some nutrient: as the growth/metabolism speed is fast (light driven), if some nutrients are low, then you risk that the plant exhaust them, thus -now genuinelly- becoming deficient.
So, if I am not wrong, high light and low nutrients (included carbon) is perfectly possible, but risky (which, I think, is just what I experiment in my garden pond under half-shaded and direct sunlight for hours, atmospheric CO2, because even my vals get fuzz algae on them).
This is how I understand it. I am over simplistic/wrong?
Thanks!
EDIT: Corrected wording and explanation.
I have read a lot of discussions and information about the needed nutrients vs deficiencies in aquatic plants. Basically they need light, macronutrients, micros and carbon. But the relations, even reading opinions/tests of people around, are not too clear to me, for example:
Light. People say that light is just like a gas pedal in a car; it controls -mainly- the 'speed' of metabolism (growth).
AFAIK light never could be too much; following Liebig's law, the growth of the plant -with enough light- will be limited by the nutrient in smallest quantities (relative to the plant maximum possible uptake for each nutrient under given light, of course). In that case, with all needed nutrients present, but in small quantities in relation to light amount (at least 1 nutrient, or more), the plant should just grow fine (but -a priori- not slower than if we would have higher amounts of nutrients, for example to allow make use of the excess of light). I feel, though, that when there is low level of nutrients and high light, there is a slow down when nutrients get more and more scarce (more difficult to find them and maybe other metabolic reasons I ignore), so some slow down would be expected, depending on nutrient amount level under (and despite) high light. Nevertheless I think light is the first order driver for growth speed/metabolism, being secondary the nutrient level if really unbalanced.
In that case, we should not be causing any plant deficiency (thus, not DOC, NH4, etc leaking from plants leaves, etc). Do I understand it correctly? Have you experimented this?
Macro, Micros & Carbon. In the same way, as far as all of them are present (with enough light amount), the growth will be limited by the one more scarce (less available) for plant to uptake. Then deficiency will not be produced in that case, only growth could be hindered (slowed down or not, depending on light amount, read above and below).
So deficiency will be caused only if there is some nutrient lacking (not necessarily just in small quantities versus light amount, etc).
The exception to this would be the 'lower threshold' (I forgot now the technical term for this) of needed nutrients, which likely will vary for each plant type. I understand that even if all the nutrients (light included now) are available there is a minimum needed amount for the plant to be, at least, in vegetative growth (so they allow the plant to be alive although not actually growing). We would not like this vegetative status as I guess it is the line between plant (leaves, etc) leaching into the water column and don't, so better to have plants growing, even if it is at slow rate.
(Of course, I assume that plants do not leach if they grow, and they leach if do not (would it be because is unhealthy/deficient, or just simple vegetate). This binary understanding may not be completely true or is likely maybe too simple, though, but I never saw this very point discussed). My opinion is that the zone between very scarce nutrients and becoming deficient is a diffuse frontier, as the nutrients get more scarce and difficult to find the growth is slowed down (even in high light) and deficiency symptoms/leakages start happening even if there is some nutrient still available: it is not the same to find that needed atom 1 per second, than 1 per hour or 1 per week, where is the frontier between "slow down" and "stablished deficiency"?)
The problem of "not balanced" light vs nutrients, as far as I see it, is not that this balance has an inherent deficiency for the plants, but only that it is more likely for them to become deficient in some nutrient: as the growth/metabolism speed is fast (light driven), if some nutrients are low, then you risk that the plant exhaust them, thus -now genuinelly- becoming deficient.
So, if I am not wrong, high light and low nutrients (included carbon) is perfectly possible, but risky (which, I think, is just what I experiment in my garden pond under half-shaded and direct sunlight for hours, atmospheric CO2, because even my vals get fuzz algae on them).
This is how I understand it. I am over simplistic/wrong?
Thanks!
EDIT: Corrected wording and explanation.
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