Why aren't my plants taller?

[memorywrangler]

My tank's been up for about 4 months and it's doing pretty well.  Basic water parameters seem fine and plant growth has been pretty strong.  Use Easy Green to keep nitrates above 10ppm.

The weird thing is that my plants refuse to grow into the top 30% of the tank.  This is true for Bacopa Carolinia on the left and center right, the java fern in the middle (it has numerous, small leaves.  The single tall one came with the plant), and the Rotala on the right.  They all see to grow about 2/3 of the way up and start leaning outward.

Any idea why this might be happening?  

[Scapexghost]

What kind of light are you using? In general, higher light=shorter plants. Plants will only grow has high as they need to. Once the plants reach a height that they receive an adequate ammount of light, theyll begin to grow outward rather than upward. 

[memorywrangler]

Ah, very interesting.  That explains a lot.  Thanks!

It's a Finnex Stingray 2.  The photo period is 10 hours a day, I believe.  Would dropping it help?

Alternately, I could try letting the Salvinia minima I have in there go wild and shade everything.

Also, is the light requirement just a function of species or is it also question of balance with respect macro/micro nutrients?  

 

Edited June 7, 2022 by memorywrangler

[Scapexghost]

On 6/7/2022 at 12:04 AM, memorywrangler said:

Ah, very interesting.  That explains a lot.  Thanks!

It's a Finnex Stingray 2.  The photo period is 10 hours a day, I believe.  Would dropping it help?

Alternately, I could try letting the Salvinia minima I have in there go wild and shade everything.

Also, is the light requirement just a function of species or is it also question of balance with respect macro/micro nutrients?  

 

Decreasing photo period will make the plants taller, but it'll also make the plants more lanky. Your plants are looking so good rn i don't necessarily recommend messing with the lighting level. If i were you a would add some stem plants like scarlet temple to the background. Most stem plants will grow infinitly tall if given the opportunity. 

Plants besides stem plants often have a maximum height. Your java fern, for example is a special type of java fern, known as "Windelov" Java Fern. It won't get as big as the normal java fern.

I don't think changing the nutrient level will effect plant height. However  If you do decide to decrease lighting levels, decrease the nutrients as well to prevent an algae bloom.

[nabokovfan87]

On 6/6/2022 at 10:58 PM, Scapexghost said:

What kind of light are you using? In general, higher light=shorter plants. Plants will only grow has high as they need to. Once the plants reach a height that they receive an adequate ammount of light, theyll begin to grow outward rather than upward. 

Light spectrum can also affect how plants grow. Green, Blue, and Red spectrums.

There's a study highlighted in this video.

https://youtu.be/eUGybNktqQg

[OnlyGenusCaps]

On 6/8/2022 at 6:33 AM, nabokovfan87 said:

There's a study highlighted in this video.

So, I know everyone wants to keep this site positive, and I do as well.  But would like to politely disagree about the utility of this video. 

As someone who got their doctorate studying, among other things, photosynthesis, I would not recommend this video as a quality source of information to understand how plants use light.  I think this video has come up on this forum before, and I very much believe it is going to cause more problems for those trying to learn about their plants than it will help with. 

That's my 2¢. 

[nabokovfan87]

On 6/9/2022 at 6:11 AM, OnlyGenusCaps said:

As someone who got their doctorate studying, among other things, photosynthesis, I would not recommend this video as a quality source of information to understand how plants use light.  I think this video has come up on this forum before, and I very much believe it is going to cause more problems for those trying to learn about their plants than it will help with. 

Totally understandable and obviously I think we all want to be providing accurate, thoughtful information. I will try to not reference the video given the concerns.  Is there anything that you have from your experience people can point to that shows plant growth based on spectrum? I know it's a common thing that's studied. I just want to point people the right way and have that information for my own lighting adjustments.

[OnlyGenusCaps]

On 6/9/2022 at 4:51 PM, nabokovfan87 said:

Is there anything that you have from your experience people can point to that shows plant growth based on spectrum? I know it's a common thing that's studied. I just want to point people the right way and have that information for my own lighting adjustments.

That's a great question and an excellent critique -  I dismissed without offering an alternative.  Fair points!

The thing is, I don't know of a good concise video like that to reference.  I've never looked one up.  Perhaps I should just so I have something to offer.  The thing is the folks who really know their stuff when it comes to plant lighting are growing a crop that...  Might violate the family friendly rules here.  Maybe?  But that's where I'd start looking.  Some of those folks could get a plant physiology degree!  Not all of them mind you.  Some of them perpetuate some really bad "information".  Still, a photobiologist colleague of mine used to say "God bless those <covert> growers who put their information on the net!"  He had more than one grad student who gleaned information from that group that allowed them to make a significant breakthrough.  🤣

Getting back on topic, the MSU study in the video with the different lights/heights has been a text book example in one form or another for a while.  Generally blue light grows more compact plants than red.  But it's really the red:blue and the red:far red ratios that are responsible for multiple signaling pathways.  We're learning that blue:far red may trigger certain developmental cascades as well, but I am starting to get into the weeds here.  No pun intended. 

But as it stands, I don't have an accessible reference on hand, and you are right, I should.  Not sure how much time I can devote to the search currently, but that is what would be most helpful.  Your point is well taken.  Thank you!

[nabokovfan87]

On 6/9/2022 at 5:08 PM, OnlyGenusCaps said:

Generally blue light grows more compact plants than red.  But it's really the red:blue and the red:far red ratios that are responsible for multiple signaling pathways.  We're learning that blue:far red may trigger certain developmental cascades as well, but I am starting to get into the weeds here.  No pun intended. 

Like I said, and always seem to repeat whenever you and I do get a chance to talk photosynthesis... SUCH an interesting topic to dive into.

I can totally understand why you have taken so much time to learn so much about it.

https://www.2hraquarist.com/blogs/light-3pillars/light-wavelength-indepth
I found this ^^ Maybe it can be helpful to guide us on the right path, but likely incomplete.

There is also a video in this post as well as a study referenced (I'm sure there's more).
https://academic.oup.com/pcp/article/50/4/684/1908367
 

Quote

Action spectrum for photosynthesis (vs absorption spectra charts), describes the efficiency with which specific wavelengths produce a photochemical reaction. The curve is also known as the Yield photon flux (YPF). PAR values all photons from 400 to 700 nm equally, while YPF weights photons in the range from 360 to 760 nm based on plant's photosynthetic response. i.e. In the McCree chart on the right, red is shown to be more efficient for photosynthesis than blue, which is more efficient than green. Some sources will also refer to this concept as PUR (Photosynthetically usable radiation).

From the chart below, it gives the impression that red light is 20-30% more efficient than blue/green light for the purposes of photosynthesis. The curve was developed from short-term measurements made on single leaves in low light. Some longer-term studies with whole plants in higher light indicate that light quality may have a smaller effect on plant growth rate than light quantity. Leaves absorb mostly red and blue light in the first layer of photosynthetic cells. Green light, however, penetrates deeper into the leaf interior and can drive photosynthesis more efficiently than red light at higher lighting levels.

 

[OnlyGenusCaps]

On 6/9/2022 at 9:13 PM, nabokovfan87 said:

https://www.2hraquarist.com/blogs/light-3pillars/light-wavelength-indepth
I found this ^^ Maybe it can be helpful to guide us on the right path, but likely incomplete.

A few thoughts on this link.

1. I think that's a pretty good primer trying to get started in understanding plant lighting and the responses plants have to differing wavelengths of light.  I still don't know where "PUR" comes from, but YPF is used for sure. 
2. I appreciated that they recognized that YPF is not as generalizable as PAR.  YPF will change temporally, ontogenetically, and plastically in response to environmental signals - in addition to varying between species.  All of that makes it really hard to make hard and fast statements about that measure in practice unless you have a lot more information fill in the necessary variables. 
3. I loved getting to see the updated figure from Tiaz & Zeiger!  I'm genuinely sitting in front a shelf with the 3rd edition they showed as outdated, right now.  And it is outdated.  Wonderful updated figure there! 
4. I didn't have time to watch the whole interview with Bruce in the embedded video, but it's nice to see him.  Haven't in a few years.  The pieces of the video I did watch were, no surprise, really informative.  There was a lot of "it depends" he included in there, and I think that's the big take away.  And not just with this stuff; there was the filtration discussion recently as well where people can take a "this is the one true answer" approach.  But the truth is that, though there are underlying unifying factors, once you build complexity on in terms of real organisms, or real systems, everything becomes far more nuanced and context dependent.  I thought Bruce hit on some of that very well in the video. 

Okay, at this point I think I've lost the interest of everyone on here except maybe you, @nabokovfan87.  Thanks for looking up that link!  I do think that's a good go to for folks to get probably as much information as they practically could need to understand lighting and their aquarium plants (with the possible exception of the elephant in the room - algal growth).  It's a good primer and a resource worth pointing to.  Well done, sir! 

[Anjum]

I'm here for the science talk too! 🙋

Thanks for looking up those sources @nabokovfan87 & thanks for weighing in @OnlyGenusCaps