tstick
Well-Known Member
Accelerated growth characteristics....plants drinking a lot more water....just an overall sense that the plants are happy under HID light.
Do any LED fixtures produce an HPS-like color?
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lusidghost
Well-Known Member
My plants never get red stems during the summer, but at the same time I posted a picture where a piece of painters tape wrapped around a branch was pulled back to reveal green while the rest of the branch exposed to light was red. So that's a little confusing.
coreywebster
Well-Known Member
Was the tape on the branch in summer?
coreywebster
Well-Known Member
So again, possibly points to that IR raising internal temps and helping transpiration.
Fallguy111
Well-Known Member
I do think my flowers prefer hps over led but for me led's have made all the other aspects of dialing in my environment much easier. Has anyone supplemented with UV and noticed anything promising?
lusidghost
Well-Known Member
I can't remember, but I don't think so because they usually stay green in the summer.
coreywebster
Well-Known Member
Yeah that makes me think it's a combination of heat to photosynthesis light ratio. As in if the heat doesn't match the amount of light in the chlorophyll a and b ranges (high in led) then we get this red stem situation.
Just theorising
coreywebster
Well-Known Member
One of my LEDs is from Aussie grow lights, their first boards with UV, though I can't remember how much UV. Possibly also with IR.
The noticeable difference from that side and the QB side is they seems to finish quicker on the AGL side and brings a bit more frost out.
Rurumo
Well-Known Member
I noticed that most of the Chinese brands have a similar mix of 3k 5k reds etc, but some definitely are more yellow than others. I hate that, it's terrible for pictures. I'm replacing my small led boards with HLG because they skip those yellow chips. I love the white light that HLG produces.
Kushash
Well-Known Member
Light irradiance can bring out anthocyanins.
This is a clip from an edu link.
Anthocyanins are flavonoid compounds that protect plant tissues from many environmental stresses including high light irradiance, freezing temperatures, and pathogen infection. Regulation of anthocyanin biosynthesis is intimately associated with environmental changes to enhance plant survival under stressful environmental conditions. Various factors, such as UV, visible light, cold, osmotic stress, and pathogen infection, can induce anthocyanin biosynthesis.
I feel a lack of Mg in veg can also cause purple stems. So many issues can cause stems to purple making it more difficult to dial in what is causing it when switching to LED especially if the strain has a natural tendency to purple also IMO.
Hooda Thunkit
Well-Known Member
Didn't Citizen make a 2200K amber cob? Also, you can drill down the options fields on Digi-Key or whatnot and select your cct. Lots of weirdness in that regard.
Don't recall a pre-built fixture at 2000ishK though.
Don't recall a pre-built fixture at 2000ishK though.
MedicinalMyA$$
Well-Known Member
grotbags
Well-Known Member
Grow Lights Australia
Well-Known Member
I'm going to reply to this post because there is certainly a lot of truth to it. Cannabis was grown indoors and selectively bred under HPS for decades which meant that those strains and individual plants that performed well indoors under HPS were bred over generations and passed on their genes.
I won't comment of HPS vs the Sun except to say that the one of the things they have in common is they both produce a lot of infra-red light which we feel as heat because IR wavelengths interact with water molecules in such a way that the energy of the IR waves is absorbed quicker than visible wavelengths. Heat, which is the transfer of energy, speeds up chemical reactions. Photosynthesis is an endothermic reaction which absorbs heat (energy). As temperatures increase most living things grow faster up to a point.
We say HPS is not as efficient as LED but that is only because HPS produces a lot of light outside the visible range so is not counted as PAR. The added warmth makes plants grow faster but only if grow temperatures are low to begin with and it also depends on the species. At higher temperatures growth will slow due to heat stress as the plant over transpires to cool itself which is not very efficient.
We are one of the few grow light companies that will not tell you that LED will outyield HPS because it is still hard to outyield HPS if everything else is optimal. HPS has a good amount of far red light which helps photosynthesis and fruiting and flowering. The extra far red and infrared will cause plants to stretch more under HPS than LED. Plant canopies are not 2D they are 3D so the HPS plant will stretch a little more and then fill in along the branches because the added stretch allows more light to penetrate and swells flowers along the length of the branch.
What we will tell you is that LED can rival HPS for yield while consuming much less energy. LED also provides better quality because it has more blue light and if it also has violet and UVA around 400nm it stresses the plant a little more into producing secondary metabolites. I know there is ongoing debate about UV and cannabinoids but we feel there is too much focus on UVB and short wavelength UVA that carries a lot of energy and not enough attention paid to the longer wavelength violets and blues that have produced good results in the tests we have done. The original High Light LED that I believe @coreywebster is using is around 2900K and has some UVA and violet from 395-430nm.
We use a lot of Nichia 2700K CRI90 diodes in our lights because we also like red and far red and have seen the results. @Prawn Connery noticed this when he was growing under Nichia diodes a number of years ago and incorporated them into the original High Light which he designed. That is the light @coreywebster is using
Grow Lights Australia
Well-Known Member
Yes we have done some tests on this and found that UVA nearer to 400nm works best because strong UV such as UVB and short wavelength UVA also degrade cannabinoids as it stresses the plant into producing them. We noticed this when we compared supplemental UVA around 400nm and UVB reptile bulbs that emitted UVB around 310nm and UVA around 365nm. The UVB lights went backwards when we tested the samples for cannabinoids which confused us at first until we thought about what was happening.
For some breeders/strains yes not for all some are selected indoors for many different reasons
Grow Lights Australia
Well-Known Member
How old are those cultivars? If they are descended from any of the Skunk/Northern Lights/Haze/Afghans that are the building blocks of most modern strains then it is almost certain that they were originally selected under HPS. The fact they were being grown in the Netherlands means they were likely indoor Dutch strains to begin with which were bred under HPS in the late 70s, 80s, 90s and Noughties. There was around 40 years of indoor growing or more using HIDs such as MH and HPS where indica genetics became more popular due to being more compact and fast-finishing. Before that many people grew sativas outdoors as a lot of the early genetics were from southeast Asia and central and south America and indoor growing was not as common.