Lighting Spectrum and Photosythesis - Page 8 - Lighting

mats808 · 08-05-2008, 10:28 PM

Here is a picture of what Bolbitis looks like when grown under low light conditions. This is not my pic but i hope it's ok since the photographer's name is printed on the bottom right corner.

It's not the best example since it only shows a single leaf and not the whole plant but it's the best I could find. Notice that the leaf is growing outward, facing the light, and not up towards the light and that it's really quite flat. The leaf is also dark green opposed to a much more transluscent yellow green. There is some variation that I've seen with different clones but in my experience even with different clones you will see the traits I mentioned much more when the plants are grown with less light.

Picture a Philodendron growing up the side of a tree with all of its leaves growing outward, facing its greatest surface area up towards the light. Can you picture the layers of leaves all facing the same direction? Like when a magician says pick a card and fans the deck out for you. It really is super pretty.

In fact, a lot of plants change their growth habit when they get more light than they are accustomed to. Many orchids do this. When many species of shade loving orchids get too much light their leaves that normally face the sky start to grow very upright in an attempt to face as little of their surface area toward the sun possible. A kind of self shading. Their green leaves also become much more greenish yellow and eventually yellowish green. Orchid growers sometimes do this on purpose to 'stress' their plants enough so that they flower.

defdac · 08-05-2008, 11:19 PM

I think you're talking about growing Crypts over the water then? I'm mostly aquascaping and growing them under the water.

I also think we have to define "lower light". In a sense all our aquariums, including the "high light" ones, can be considered shady compared to direct sun light.

We're also mostly growing weeds, including the fancier plants harder to come by. As they are weeds they are not that picky about their light levels and very few hobbyists, if any, can manage to dish out the 600 micromoles/m^2/sec where the plants gets light saturated. When they get light saturated they just keeps photosynthesize on their highest level. Under water plants have enough humidity and stable temperatures to keep going at it as long as there are CO2 and nutrients.

Quote:

Please understand that I'm not cutting down your culture in any way

Well you just did, and frankly I could care less since you haven't shown anything that comes close yourself. You seem to be the typical sci-fi-dream-talker, and I'm more of the pragmatic scientist that loves to share ups and downs of my hobby. Put you money where you mouth is and show us your beautiful tanks instead. That will shut me up and make me crawl down under my stone for sure =)

But let's get back on topic. We seem to agree that green light is not as efficient growth speed wise.

So let's talk about evolution and how green plants adapt to grow in the shade under canopies with green light. They get leggy and strive to get up to the blue light as fast as possible. I've read up on how plants know they are shaded. They look at how much far-red irradiance there is around them. Under canopies there are alot of far-red light.

When they reach the blue light with relatively lower amount of far-red then will spread out and try to shade their competitors.

This growth pattern is fairly easy to see for an above average aquascaper that have their closet full of different light bulbs with different spectral distributions. Some bulbs, often with less blue and more red, will get the plants very leggy. Other bulbs with more blue, less red, will grow them very horizontal and making them hug the ground.

This is an evolutionary adaption to overcome the problems associated with not getting enough light.

And again. Most hobbyists hovers around very low irradiances, mostly below 100 micromoles/m^2/sec usable radiation, where the problem is getting enough light to break even and even reach the compensation point where respiration=photosynthesis.

And then comes the somewhat idiotic idea to spend more electricity on dishing out more green, unusable, light? Come on =)

mats808 · 08-05-2008, 11:55 PM

What you say about plants searching for more light under the canopy is true of many species. Many of these plants actually prefer higher light and are simply competing in a race for more light. With many species it is a race to the top where the light is more abundant.

The thing is that these are only some, actually most of the plants. You are forgetting about all the plants that like the forest floor. The plants that have evolved to live there. The plants that really don't like bright light and actually prefer the shade.

So yes you are right that some plants, maybe even most plants will get leggy, and search for the light. But this is not true of all plants. and these are the plants that Amano was talking about in his quote. He wasn't talking about plants that are forced to grow in lower light until they can reach the top of the canopy and bask in the sunlight. He was talking about the plants that actually like where they have evolved over tens of thousands of years to live.

Have you ever hiked in a tropical/sub-tropical rainforest? If you did you should have noticed that there are certain species of plants that will only grow in the shade. You can actually see them growing along a wall of rock.....nicely down the line....and then all of a sudden the line stops because there is too much light in this section. Then you go a little further and the shade returns and so does the nice little line of that particular species. Although you find it so hard to believe, certain plants prefer the shade.

As far as offending you, again, even though you don't care....i apologize. I don't know if you noticed but I did mention that it is a personal preference of mine. I also mentioned that bright light is great as Bolbitis does grow faster.

As far as me not showing anything....unfortunately because of work and other things in my life I choose to keep but a few tanks. With these few tanks, I choose to keep breeding pairs of wild Bettas. I am keeping Betta macrostoma and Betta pallifina. My male macrostoma is my avatar. I actually have fry right now. If you like when they grow a bit I could send you some if you are interested. Unfortunately I do not currently have a 'display tank'. It actually saddens me a bit but with the little time I have I have chosen to focus on breeding fish instead of creating beautiful aquascapes. I am currently keeping a few plants that I really like but these plants are kept because of rarity or simply because they're some of my favorites and not for aquascaping purposes. Like you mentioned I have a few emersed Cryptocoryne species that I really like. I am growing two pieces of Cryptocoryne cordata 'Rosanervig' submersed. And I have a Microsorum species that is 'fingered' if you will.

defdac · 08-06-2008, 12:11 AM

I think we agree on pretty much everything.

There are of course some species better adapted to cope with less light - as we mostly have in our tanks.

"Beginner" plants like ferns, anubias and moss.

They will grow beautiful with the meanest hood you can get though - you will not have anywhere near sunlight anyway.

nosoop4u246 · 08-28-2008, 12:00 AM

As difficult as it was for me to read though this whole thread, dogging my way through pages 5, 6, 7, and 8 of Defdac attacking Mats, I did manage, and thoroughly agree with Newt. With as much as I found myself disliking Defdac by the end of the post, he did make a (singular) good point: if the plants are green in appearance, they are reflecting green light, and if they are reflecting green light, they are not using it. If any of the commonly kept aquatic plants are using green light, it would be the Ammania senegalensis, the Alternanthera reineckii, the Nymphaea rubra-- the reds. I use a mixture of bulbs in a fairly unconventional way to get the reds and blues in, and I'm sure I'll take some flak for it, but halogens work very nicely in conjunction with any strongly blue-peaking bulb (I have Coralife's 10,000K bulb).

"Standard" halogen:

defdac · 08-28-2008, 12:56 AM

Yes I was a bit harsh perhaps hm..*blush* That kindof defeat the purpose of forums, and I really like discussing lighting. Sorry for coming out a bit rough hm..

Commodore 64 · 09-02-2008, 09:48 AM

Well, I think sometimes written thoughts seem more harsh when read.

For me, I'm a complete nub...I'm just trying to grow hornwort, java moss, java ferns, moneywort, banana plant, swords, crypts and some grasses in my aquarium. I really have no clue what my lighting really is, as it's a shoplight, on a homemade little frame of stained oak. So I doubt I get optimal reflecting of the light. I do know that I've got 2 T8 6500k 32w bulbs, one overdriven x 4 and the other overdriven x 2 on a 55g, 19 inches above my substrate.

I read threads like this and the other stickied ones which talk about lumens per watt, PAR, PUR and whatever....and I really can't figure out a way to correlate that with my ODNO lights (or any lights). It truly does seem to be an art as much as it is a science.

This whole lighting thing seems so cryptic and complicated when you look at it at such depth as this thread...and that doesn't even factor in ferts and CO2!

I guess I'll let my plants tell me what my lighting conditions are (i.e. see what grows). The dwarf hairgrass doesn't seem to be doing anything, it is slowly atrophying. The hornwort is going ape**** but that seems to be the norm.