Effects of differing wavelengths of light on cana growth.

[Randalizer]

so not wavelength related buuuut......

Here is a pic of a linear rail and why it helps. The only thing about the pic I don't like is that the smaller plants would be leaning in towards the center of the picture, where the light is stationary.

Edited June 9, 2009 by Randalizer

[Indicanights]

The wavelength of UVB in these reptile bulbs is even lower than MH bulbs, not bad for £22.

Hagen Exo Terra 10.0

Link apologies if considered spam http://www.petzoo.co.uk/product_info.php?products_id=717

The 26W cfls claim to have an effective range of 50cm so 4 of those in a 1m x 2m room could have an interesting effect i may investigate if I am $$$ with a month to go.

What think you Randalizer?

[Randalizer]

Whoops. Somehow missed your Q. I can't check your recomendations ATM (textng), however if you want to use UV for supplemental lighting I strongly suggest reading the UV topic I have linked in an earlier post in this topic. As well you should read Felix and Pro's topic in the Strain/Breeding forum. Called felix and pro's most ultra violet adventure, it details how to use supplemental UV lighting meant for reptiles.

I'll provide a link when I can.

WARNING: When using supplemental UV light, one needs a UVB meter to gauge the strength of the radiation levels. In addition protective clothing (long sleeve shirts and thick gloves) and UV blocking glasses are strongly suggested to prevent skin cancer and glaucoma.

[ReverendRFB]

Great read.. good new developments. I'm interested in the UV thing too but I'll need more time to research it.

I had just wondered.. well I've been wondering.. about my reduction in flower time....

One point of information I forgot to include.. that could potentially be a factor.. is that I leave my MH light on 24 hours a day, 6 days a week. On the 7th day, I turn off the light for 6 hours to cool down and stuff.. But then its back to 24 hours of light.

Is it possible that the light regiment is somehow contributing to the reduction in flower time?? -I wonder as I think while stoned- Even when the light is off for those 6 hours, the room is not dark because of the flouro's vegging the mum's, seedlings, and clones. Those never turn off.... so even during those 6 hours the plants are still receiving light... So really.. they never experience any darkness at all until their first night in the flowering room. So... does having these things vegging for like 4-6 weeks straight with no interruption in light - contribute to their early maturation?

hmmm.......

[Randalizer]

however if you want to use UV for supplemental lighting I strongly suggest reading the UV topic I have linked in an earlier post in this topic. As well you should read Felix and Pro's topic in the Strain/Breeding forum. Called felix and pro's most ultra violet adventure, it details how to use supplemental UV lighting meant for reptiles.

I'll provide a link when I can.

And here it is.

Indicanights. Imo it is far more important to get the rest of a grow room (standard lighting, extraction, compost, etc) sorted before trying UV supplemental lighting. And then getting a UVB (the wavelength we are most interested in in the UV range) meter before the UV lights so you can tell what you are doing to your plants.

Edited June 11, 2009 by Randalizer

[Randalizer]

hmmm.......

Time to run some tests Rev! 1st start collecting data on what you currently are doing and write it down somewhere!

[Randalizer]

A few reference charts in one handy topic! All from wiki. Visible light is 400 to 700 nm.

Name...............................Abbreviation...............Wavelength range in nanometers...............Energy per photon

Ultraviolet A, black light..........UVA...............................400 nm–320 nm.................................3.10–3.94 eV

Near.................................... NUV...............................400 nm–300 nm..................................3.10–4.13 eV

Ultraviolet B,medium wave.....UVB................................320 nm–280 nm.................................3.94–4.43 eV

Middle...................................MUV...............................300 nm–200 nm.................................4.13–6.20 eV

Ultraviolet C, short wave,

or germicidal........................UVC................................280 nm–100 nm.................................4.43–12.4 eV

Far.......................................FUV.................................200 nm–122 nm.................................6.20–10.2 eV

Vacuum................................VUV.................................200 nm–10 nm...................................6.20–124 eV

Extreme................................EUV.................................121 nm–10 nm...................................10.2–124 eV

Edited June 11, 2009 by Randalizer

[Keye]

Hello all.

This is an interesting thread as i am now running a MH throughout flowering to see what happens. I've always heard that MH gives 'better buds' but fewer of them.

I run a 250w Lumitek ballast - the one thing with 250w is that there is very little penetration into the canopy. All the good stuff happens in the first few inches. So, if you can promote shorter stockier growth then you will benefit with, basically, bigger buds. Instead of the buds stretching out along a branch, with the potency dropping away the further from the top it is; having shorter nodes with that bud on them is a much better option.

This consideration is a lot less with the bigger lamps, 400 or 600w, as they go right through the canopy and you can usually be assured that a bud from under a 600w will be 'thick' all the way down.

From the little reference I have, the MH has made the plant start flowering a lot quicker than normal. This is the first time i've grown this cut but talking to the donator has led me to believe that this is definatly the case. He sees flowering start at week 3ish. I'm on week 3 now and i reckon the buds are set and starting to compact and build. Not only that, but the stems are a lot thicker also. Thicker than the donators plants on a 400w HPS.

Keye

[mrswoo]

As I posted in my first post, I've never grown canna. However, I've done a fair bit of research on it. The sun produces equal amounts of each wavelength of light between certain parameters. HPS bulbs tend to produce more red light than MH bulbs and as a result you can get stretchier plants, larger internodal distances and generally weaker branches which is not what you want to hold your buds! The HPS are also of more benefit to flowering plants because more of the red spectrum is used. MH bulbs produce more of the blue wavelength that is lacking in the HPS and as a result plants develop thicker, stronger stems and don't tend to stretch so much. I can't comment on LEDs, fluorencents or dual spectrum HPSs but I would guess that the dual spectrum HPS bulb is produced in such a way that the missing blue wavelength has been compensated for and that they produce a healthy balance between the two. I know nothing about the radiation they might produce or wavelengths outside the visible spectrum so can't really comment!

Alex

[mrswoo]

mrswoo here you guys are well advanced in this subject wherse the kindergarden?

[Randalizer]

mrswoo here you guys are well advanced in this subject wherse the kindergarden?

I would start in the lighting forum and read the stuck topics. You want to start with reading all the safe issue topics. You can also click the knowledge base button on the top right of your screen and do searches in there for basic stuff.

[Mr Greenhorn09]

I found this thread to be really helpful. Thanks to everyone that contributed information. It is a great source.

[Davey Jones]

I grew with MH only for quite a while, just under a year running a perpetual crop, I definitely noticed a difference in potency nothing major but in the end the drop in yield was just far too much to swallow, around 30-40 percent!!!!!!!!!!!!!!!!!!!

The HPS lamp is more efficient and the lumens really count

[theguyman]

This may bit old, but I felt compelled to share what I've concluded after about 5 years of researching and plant sensors.. I'll keep it short and to the point.... please bear with me as this might clear up a lot of misconceptions... especially with penetration.

First off.. i'd like to talk about wavelength and penetration. Chlorophyll absorbs absorbs reds and blues the best. Wavelengths in the yellow spectrum pass through more easily than red(660nm) and blue. Far-red(730nm) also passes pretty easily. Its extremely important to differentiate reds and far-red as they cause polar opposite phytochrome effects.

Think about this one concept clearly.... The colors that are absorbed the most will logically penetrate the least!!! PENETRATION IS NOT STRENGTH!! penetration means LOW absorbance!!! This doesn't mean you can just have blue and red light though... The reds (630-660nm) and blues get filtered by the first layer, but the yellows penetrate further down. This allows the lower branches to see more yellow and far-red (730nm) than it sees red (660nm) and thus stretches more.

Get me? the better quality light gets absorbed by the top branches while the lower quality light tells the bottom branches to stretch out like an xmas tree until they get the same shade of light as the top branches.

PENETRATION IS THE OPPOSITE OF THE CHLORAPHYL ABSORBANCE CURVE. THE INVERSE OF ABSORBANCE IS TRANSMITTANCE(penetration)!

Edited August 31, 2009 by theguyman

[theguyman]

Phytochromes are the most important sensor governing the shape (localized stretching) of the plant. I have attached an aborbance chart for Pr and Pfr in this post. The different of absorbance of the two at a given wavelength determines %Pfr the branch will converge at. Using that chart, you can approximate the %Pfr each given wavelength will induce. %pfr is essentially color vision for plants. Here are a few examples:

wavelength ----- %Pfr

730nm ----- 0% (only place where Pfr absorbs but Pr doesn't at all! get it? this is key!!)

660nm ----- 85%

630nm ----- 77%

600nm ----- 69%

520nm ----- 50% (Pfr and Pr absorb equally here so %Pfr converges at 50%! get it now?????)

Differences below 500nm are minor and could likely be dismissed. I eyeballed this chart btw.. don't hold me on the percentages. I'm just eyeballing the differences between Pr and Pfr absorbance at those wavelengths because thats what's important.

Now.... Heres where this becomes important.... The stretch rate of a given branch is logarithmically proportional to its local %Pfr!!! I have included a graph here to show how stretch rate is logarithmically proportional. This is important information in determining why certain types of lights cause certain shaped plants!

From my previous post, remember that the best quality light gets absorbed in the first few layers. Those top layers see a high %Pfr. The lower layers lack the higher quality 660nm light but still receive the somewhat useful yellow light. These branches will converge at a lower %Pfr than the top branches thus causing them to stretch out until they find a direct source of 660nm. The stretch graph shows this.

HPS is very high in yellow and this is why it penetrates so well. The reds get absorbed by the top layer while all of its yellow bombards the lower levels more evenly. Its the reason for the xmas tree shape! (i said it again). Yes yellow light causes stretching, but without the contrast of yellow and red, all the branche will think the light is perfect everywhere and thus won't perform shade avoidance on the lower branches. Unless you can truly get high levels of red (630-660nm) to every part of the plant, yellow is essential.

Here's an analogy. Walk into a room only lit with one wavelength (try 660nm) and you'll be color blind! You won't be able to make correct judgments and know how to perform in your environment.

Edited August 31, 2009 by theguyman