Aquatic Plant Forum banner

1 - 10 of 10 Posts

·
Banned
Joined
·
2,069 Posts
Discussion Starter #1
Phil, if red need more light, why are cactus and desert plants all green and why are tropical rainforest plants deep in the jungle red?

That's counter to the entire notion of red needs more light.
Few emergent plants are red, red plants that grow out of the water become green.

It takes a lot of N to produce Chl, not much to make red which will catch lots of light and make the Chl a more efficient and the plants can have far less N per unit of leaf area.

There are many things a plant can do to get more light or reduce the amount of light.

I do not buy that red plants need more light nor iron. Never have.

Regards,
Tom Barr
 

·
Registered
Joined
·
2,173 Posts
Tom,

That's interesting stuff!! "Feed me, Seymour!" :shock:

if red need more light, why are cactus and desert plants all green and why are tropical rainforest plants deep in the jungle red?

Desert plants are green because ChloroPhil (hahaha) is more efficient. They've got other adaptations, like photosynthetic trunks or needles rather than leaves (generally). Why aren't all tropical plants red?

Understory plants/autotrophs in any super dense/highly filtered ecosystem, be it a rainforest or 200' under water will have high percentages of red pigments. Only the highest energy light (blue to ultraviolet on down) is able to penetrate to those depths. Since red pigments are the most efficient at capturing that higher energy radiation the plants will produce more red than anything else. That's not to say that others aren't produced as well on the off chance that a large tree might fall and create an extra light situation. I've got a lot of Begonia species in the conservatory at school with green tops and red bottoms to capture the greatest spectrum possible.

That's counter to the entire notion of red needs more light.
Few emergent plants are red, red plants that grow out of the water become green.


True enough. However, with the increase in the red spectra once out of the filtering/reflective capacity of the water the plants are better able to utilize the lower energy end of the spectrum and start producing Chlorophyll in amounts able to mask the Carotenoids.

It takes a lot of N to produce Chl, not much to make red which will catch lots of light and make the Chl a more efficient and the plants can have far less N per unit of leaf area.

If the red pigments are so useful why aren't they the dominant pigment? :) I've got no argument with you there, the combination of pigments is most effective.

There are many things a plant can do to get more light or reduce the amount of light.

I wasn't trying to suggest that the plant is attempting to reduce the amount of light, rather, they build more red pigments to capture the increased blue light and so harness the higher energy radiation rather than let it affect their physiology.

I do not buy that red plants need more light nor iron. Never have.

I would argue that plants with higher percentages of caretoids to chlorophyll will need more light simply because of the decreased ability of the carotenoids to capture and utilize the light.

Even so, I still believe that Nitrogen deficiency is the main cause of red coloration in plants. I've had some pretty green "red" plants under some pretty strong light in some well supplimented aquariums.

Best,
Phil
 

·
Registered
Joined
·
88 Posts
I dont know what either of you just said :D but if you would like my personal experience with reds, its this; my reds didnt turn red until I added phosphate. Also way back when I was clueless and didnt dose nitrates, my reds still came out pretty deep. I will also mention that the lighting at the time was 72 watts over a 10 gallon. Pardon if my info is totally irrelevant. :shock:
 

·
Registered
Joined
·
156 Posts
Clue me in! Love this in deepth kinda things. I lost my wonderfull red color when I installed MH lightning (all daylight). After trying to dose No3 and Po4 like crazy and still not getting the color I want, I'm going back to tubes for now :evil:
 

·
Registered
Joined
·
298 Posts
It took my tank a couple of months with 2.75 ppm PO4 + 2 ppm NO3 dosage 2-3 times a week before I started getting good red colors.

Before my dosage was 0.5 ppm PO4 + 11 ppm NO3 each dose and the NO3-levels hovered around 10-20 ppm when I measured it with JBL-test kit.
 

·
Registered
Joined
·
4,700 Posts
Let me trot out a theory that may explain why some aquarium plants are more red when N deficient. The theory is that, when N deficient, plants make an excess of carbohydrates. They wouldn't have an excess of carbohydrates if they had enough nitrogen because they could convert the carbohydrates into amino acids and then into proteins which would be used for growth. Since growth is slowed for lack of protein, the carbohydrates build up and some of these are diverted into making red pigments.
 

·
Registered
Joined
·
459 Posts
I thought that when plants have red leaves it's because they are reflecting red light and absorbing blue light.
 

·
Banned
Joined
·
2,069 Posts
Discussion Starter #9
You can see the arguement of past on the APD.

Name one red desert plant.
Why aren't more desert plants C4?
Many are CAM or else annuals.

Significant filtering doesn't occur in the upper 3ft of water where most submersed plants occur in clear water.

I've got a lot of Begonia species in the conservatory at school with green tops and red bottoms to capture the greatest spectrum possible.
?
Well you are proving my arguement, you need less light for reds then?

the red pigments are so useful why aren't they the dominant pigment?
Err, they are in many cases. Depends on the leaf/plant/phenology/development/nutrient status etc

Phil, give me one good reason a submersed plant would bebefit from blue light?

Blue light will cause the stomata to open more.
Hydrilla has no stomata, what is the advantage in an aquatic system then?

Diffusion through the very thin leaves of many aquatic plants is enough.
SAM's have reduce cuticles and many other adaptions to increase CO2 gathering.

I have never seen nor heard of any blue light=> increase growth rates in SAM's to date.

There may be some, I've never seen one yet though.
Terrestrial systems yes, but not SAM's.(Submersed Aquatic macrophytes)

would argue that plants with higher percentages of caretoids to chlorophyll will need more light simply because of the decreased ability of the carotenoids to capture and utilize the light.
Carotenoids help make Chl more efficient, not the reverse.
If you have less N, then you can only build a few Chl molecules.
So more Carots would help run the Chl you do have at a more efficient rate.

Heck, you can try it your self and see.
Use less light.

BTW, adding PO4 does what to NO3 levels?
Causes them to drop.

PO4 buyself does not play that large of a role with color, N is the main player with most plants.

Having less light will allow more stable NO3 levels(and/or more reliance from fish waste) vs higher light.

Regards,
Tom Barr
 

·
Registered
Joined
·
2,173 Posts
plantbrain said:
You can see the arguement of past on the APD.

Name one red desert plant.

Why aren't more desert plants C4?
Because they don't need to be. They've come up with other adaptations to their environment. Such as:

Many are CAM or else annuals.

Significant filtering doesn't occur in the upper 3ft of water where most submersed plants occur in clear water.

Ok, then what about their physiological differences? Submersed foliage isn't as hearty as emersed foliage. The need for greater foliage surface to water contact stimulates the plant to grow leaves with a thinner cuticle and less sturdy foliage. The lack of protection prompts the plant to put out more blue light absorbing pigments in order to utilize the greatest spectrum as well as to protect itself from harmful radiation.

I've got a lot of Begonia species in the conservatory at school with green tops and red bottoms to capture the greatest spectrum possible.
?
Well you are proving my arguement, you need less light for reds then?

Yes and no. They grow just fine in open areas, but in the conservatory we've placed them under lots of foliage where they recieve filtered light. Since the great majority of them have Chlorophyll in the upper portions of their foliage already they're able to use the higher light made available to them as we make it available. The high amounts of red pigments also allow them to be more successful in the shadier areas than the species without that adaptation.

the red pigments are so useful why aren't they the dominant pigment?
Err, they are in many cases. Depends on the leaf/plant/phenology/development/nutrient status etc

Ok. I was out in a couple exposed wetlands yesterday and most of the aquatic herbacious plants were very green. These particular places were fairly nutrient poor, yet the plants were still green when emersed, but were red submersed, even right under the water's surface. They're not able to utilize atmospheric Nitrogen so I discounted sufficent levels of N. Why is this?

Phil, give me one good reason a submersed plant would bebefit from blue light?

Given that red pigments are reflecting the light most used by the plants )~670-700nm) and knowing that red pigments are able to utilize blue light effectively increasing the amount of blue spectrum for plants with high amounts of red pigments makes sense. If the plants didn't utilze blue light they'd be blue.

Blue light will cause the stomata to open more.
Hydrilla has no stomata, what is the advantage in an aquatic system then?

It seems to me that Hydrilla is adapted to uptake CO2 and other essentials directly through its "skin" as well as through aerial and subsurface roots.

Diffusion through the very thin leaves of many aquatic plants is enough.
SAM's have reduce cuticles and many other adaptions to increase CO2 gathering.

I have never seen nor heard of any blue light=> increase growth rates in SAM's to date.

I wasn't trying to suggest originally that blue light would increase growth rates. It may increase the amount of red/yellow/orange pigments in the leaves though. We started this topic as a discussion of Nitrogen deficiency and the effect on plants. :)

There may be some, I've never seen one yet though.
Terrestrial systems yes, but not SAM's.(Submersed Aquatic macrophytes)

would argue that plants with higher percentages of caretoids to chlorophyll will need more light simply because of the decreased ability of the carotenoids to capture and utilize the light.
Carotenoids help make Chl more efficient, not the reverse.
If you have less N, then you can only build a few Chl molecules.
So more Carots would help run the Chl you do have at a more efficient rate.

Sure. However, when the plant is breaking down chlorophyll to get at the nitrogen in it the plant will then have a higher ratio carotenoids to chlorophyll. Since the plants original ability to utilize the light given is lessened with the loss of the chlorophyll it makes logical sense that increasing the light/shifting the spectrum of light will allow the carotenoids to play a greater role in photosynthesis.

Heck, you can try it your self and see.
Use less light.

BTW, adding PO4 does what to NO3 levels?
Causes them to drop.

PO4 buyself does not play that large of a role with color, N is the main player with most plants.

That's what this topic is supposed to be about. Let's get back to it.

Best,
Phil
 
1 - 10 of 10 Posts
Top