Light studies recommend high intensity: 900 and 1800 mols

  • Thread starter effexxess
  • Start date
  • Tagged users None
I

Its420anytime

55
18
My first two replies were not attacking or trolling. Is this about blurples or intensities? And thread topic ask no question. I stated Depend on your grow buddies as opposed to a bunch of charts that a handful even understands.
And 1000s successful grows using all kind of methods that work including lights hardly sounds like a troll. Good advice, trust your buddies.
 
M

mannitu68

102
43
Firm believer in this for hybrid. High intensity lighting in veg for pure sativa or close to it is redundant though
why you saying that? because this guys grow fast and large anyway?

man, took me only 2 min reading to put my hand on the dimmer. Pumping 210 watt on a 70x70 now. If its enough time for a big difference, im already 40 days into flower.
 
M

mannitu68

102
43
If he didn't like my first reply, he didn't have to respond, yet he went to the effort to find out what he could by researching me, then attacks me. Proofs in the pudding,
i do that, too. If somebody is totally off, i look into his old threads to see if he just has a bad day or is a fool in general.
 
I

Its420anytime

55
18
Lol, the study done the past couple of years. Past 15 plus years.

They cite references on the other 95% of research omitted in this thread back to mid 2000s. Mid 2000s, no cob or quantum board, same same. Yet they cite studies done prior to key inventions to our needs, grow lights.

The hypothesis, abstract data, conclusions and lots of other graphs not posted to substantiate research or the study on light intensity for thread purposes.

What is the point with that patent number I posted? 2013,14, it opened the door for leds. Chinese used the word quantum before hlg trademarked the word only.

So yes, I did my research prior to my posting.

I should have mentioned 95% of hypothesis was missing to draw a conclusion on posted subject matter. And when led technology changed for growers, it was after that patent came, after the invention of the cob, circuit on the board, you know, that patent I referenced.
In my honest opinion, studies that cite studies prior to yhe technology we are currently using is outdated. There are 30 to 40 peeps cited for their studies done on other research topics that contributed to the writing of this study since early 2000s.
Apparently it was dead in the water as shown by the number of posts it received. .
 
delps8

delps8

31
18
Here let me help you. Pretend like the “window stickers” / graphs aren’t there. Ahh much better.

Now, let’s make a contribution. I’ve never ran lighting above 600 umol in veg. and 1,000 umol in flower. I’m interested in learning more from those that have.

Have you ran above average light intensity/umols successfully?
I'll poke my nose in on this. First item, I would simply disregard such comments - "When you wrestle with a pig, the pig loves it but you just get dirty."

Re. high DLI's - it's a soapbox that I've climbed up on a few times on different forums but I haven't put together a comprehensive document on it. Bugbee has done research (net photosynthesis and yield) and you can look for the Chandra paper (which documents net photosynthesis). Zheng is one of the co-authors of this paper - Google his name and you'll find other research that he's done. There are a handful of other papers that buttress the basic arguments. Bugbee calls cannabis a "high light crop" and I can't find anything, anywhere that contradicts that. Another name to toss in the hat is Debacco. Check out his videos on YouTube. He doesn't do research but he does cite his sources.

Personal anecdotes are nice but they're anecdotes, not data. While I've had excellent results with "turning it up to 11", that's just an anecdote. My advice - go with the published results of people how have been studying plant biology for decades. They put their careers on the line with each paper they publish.

For me, I "turn it up to 11". I'm now starting my fourth grow and I'm following a "high light" approach. I'll post those values but here are the values for my third grow:

1666157130527


My comment on 6/8/22 was about the DeBacco video. The meaning of that is that I finally got my head out of my ass about boosting my light values. I've read a lot of research but was, for whatever reasons, following the DLI numbers that a lot of growers use as well as the info from growlightmeter.com and Shane at Migro. I was really torn between following the advice some those sources vs what Bugbee, Chandra, Zheng, etc. are reporting. What I finally accepted is that unless they're citing sources it's just someone's opinion and, sure, you can get a great outcome at a DLI of 45 but, like Bugbee says, growers are "leaving money on the table".

Per my comments in the Excel document above, I bumped the light into the 900's and then turned it down because there was so much weed in my tent that there was no reason to run the driver at 100%. I ran the rest of the grow at a DLI of about 52.

I used the X3 for the main part of the tent but I did have two branches that wouldn't stay in the tent so I hung a little Vipar Spectra XS-1500 over them. All told, the yield was almost 730 grams with one plant at 590 and the other at 139 grams.

With a yield of about 1 ½ pounds from a 2' x 4' tent, I took a liking to the idea that more light = more weed and I've followed that in my current grow.

Current grow - due to temps in the 90's for a few days, the first week or so was indoors (on the floor of my office) and the lighting was a Vipar Spectra XS-1500 and a Royal Blue LED puck. After about a week, the heat subsided and I moved the plants to the tent where they were vegged under a Growcraft X2 veg light + the Vipar Spectra. When the plants switched to flower, I swapped out the X2 and swapped in the X3 full cycle/flower light.

The DLI data is below. The veg light has made the plants very compact and the foliage is stunningly thick - it's essentially impenetrable. With the red heavy spectrum of the X3 and this being early flower, I'm seeing significant vertical growth, on the order of an inch or so a day.

1666158369469


Previous grow, shortly before harvest.

1666158527970
 
1666157107692
delps8

delps8

31
18
why you saying that? because this guys grow fast and large anyway?

man, took me only 2 min reading to put my hand on the dimmer. Pumping 210 watt on a 70x70 now. If its enough time for a big difference, im already 40 days into flower.
That's late in the grow cycle but better late than never.

I use an Apogee but I've been testing a Uni-T light meter against the Apogee when testing a Viper Spectra XS-1500 and with the Growcraf X2 (veg). In both cases, when I took a reading from the light meter and multiplied it by 0.015, I got essentially the same number as the Apogee.

Light is food to a plant so increasing PPFD and DLI will, generally speaking, be a good move. As Bugbee says, you can't just crank up the engine and not beef up the brakes, as well. If you're going to increase light levels, the other factors in the grow environment need to be dress right dress, as well.

The light saturation point for cannabis is 800-1000 µmols and you need to check plants for light avoidance if you're going to run high light. In the past few weeks, I've hit that twice. Typical behavior is that leaves rotate around their horizontal axis; they will taco/canoe so as to avoid light; or they rise vertically, along the axis of the petiole. If you see that, drop your PPFD by 50 µmols. The leaves should start to turn back to their normal orientation in about ½ hour. The times when I got light avoidance were a result of PPFD's of over 1100µmols with DLI's in the low 70's.
 
Homesteader

Homesteader

3,264
263
The light saturation point for cannabis is 800-1000 µmols and you need to check plants for light avoidance if you're going to run high light. In the past few weeks, I've hit that twice. Typical behavior is that leaves rotate around their horizontal axis; they will taco/canoe so as to avoid light; or they rise vertically, along the axis of the petiole. If you see that, drop your PPFD by 50 µmols. The leaves should start to turn back to their normal orientation in about ½ hour. The times when I got light avoidance were a result of PPFD's of over 1100µmols with DLI's in the low 70's.

Some strains can take more light than others.
If you are increasing umol , you also need to increase CO2 as well and then water and feed.
 
Potfairy

Potfairy

39
18
These studies from the past two years recommend very high light intensities. 900 in veg and up to 1800 in flower. Study extracts follow:


Cannabis Yield, Potency, and Leaf Photosynthesis Respond Differently to Increasing Light Levels in an Indoor Environment 2021
Victoria Rodriguez-Morrison, David Llewellyn and Youbin Zheng

The objectives of this study were to establish the relationships between canopy-level LI (light intensity), leaf-level photosynthesis, and yield and quality of drug-type cannabis. … Plants were grown for 12 weeks in a 12-h light/12-h dark ‘flowering’ photoperiod under canopy-level PPFDs ranging from 120 to 1800 μmol·m-2·s-1 provided by light emitting diodes.

… dry inflorescence yield increased linearly with increasing canopy-level PPFD up to 1,800 μmol·m−2·s−1, while leaf-level photosynthesis saturated well-below 1,800 μmol·m−2·s−1. The density of the apical inflorescence and harvest index also increased linearly with increasing LI, resulting in higher-quality marketable tissues and less superfluous tissue to dispose of. There were no LI treatment effects on cannabinoid potency, while there were minor LI treatment effects on terpene potency


View attachment 1284305
FIGURE 1 | Relative spectral photon flux distribution of Pro650 (Lumigrow) light-emitting diode (LED) fixtures.
Blurple” light. The photon flux ratio of B (400–500 nm), green (G, 500–600 nm), and R (600–700 nm) was B18:G5:R77.

It was predicted that cannabis yield would exhibit a saturating response to increasing LI, thereby signifying an optimum LI range for indoor cannabis production. However, the yield results of this trial demonstrated cannabis’ immense plasticity for exploiting the incident lighting environment by efficiently increasing marketable biomass up to extremely high—for indoor production—LIs. Even under ambient CO2, the linear increases in yield indicated that the availability of PAR photons was still limiting whole-canopy photosynthesis at APPFD levels as high as ≈1,800 μmol·m−2·s−1 (i.e., DLI ≈78 mol·m−2·d−1).

View attachment 1284307
FIGURE 6 | Sketches of Cannabis sativa ‘Stillwater’ plants grown under low (A) and high (B) photosynthetic photon flux density (APPFD), 9 weeks after initiation of 12-h photoperiod

Overall, the impact that increasing LI had on cannabis morphology and yield were captured holistically in the plant sketches in Figure 6, which shows plants grown under higher LIs had shorter internodes, smaller leaves, and much larger and denser inflorescences (resulting in higher harvest index), especially at the plant apex.

Increasing Light Intensity Enhances Inflorescence Quality. Beyond simple yield, increasing LI also raised the harvest quality through higher apical inflorescence (also called “cola” in the cannabis industry) density—an important parameter for the whole-bud market—and increased ratios of inflorescence to total aboveground biomass (Figures 7B,C).

View attachment 1284309
FIGURE 7 | The relationship between average apical photosynthetic photon flux density (APPFD) applied during the flowering stage (81 days) harvest index (total inflorescence dry weight / total aboveground dry weight) (B), and apical inflorescence density (based on fresh weight) (C) of Cannabis sativa ‘Stillwater’. Each datum is a single plant.

CONCLUSION. The results also indicate that the relationship between LI and cannabis yield does not saturate within the practical limits of LI used in indoor production. Increasing LI also increased harvest index and the size and density of the apical inflorescence; both markers for increasing quality. However, there were no and minor LI treatment effects on potency of cannabinoids and terpenes, respectively.





Melissa Moher, David Llewellyn, Max Jones and Youbin Zheng


Abstract. Although the vegetative stage of indoor cannabis production can be relatively short in duration, there is a high energy demand due to higher light intensities (LI) than the clonal propagation stage and longer photoperiods than the flowering stage (i.e., 16 – 24 hours vs. 12 hours). … To determine the vegetative plant responses to LI, clonal plants of ‘Gelato’ were grown for 21 days with canopy-level photosynthetic photon flux densities (PPFD) ranging between 135 and 1430 μmol·m-2·s-1 on a 16-hour photoperiod (i.e., DLI daily light integrals of ≈ 8 to 80 mol·m-2·d-1). Plant height and growth index responded quadratically; the number of nodes, stem thickness, and aboveground dry weight increased asymptotically; and internode length and water content of aboveground tissues decreased linearly with increasing LI. … Generally, PPFD levels of ≈ 900 μmol·m-2·s-1 produced compact, robust plants that are commercially relevant, while PPFD levels of ≈ 600 μmol·m-2·s-1 promoted plant morphology with more open architecture – to increase airflow and reduce the potential foliar pests in compact (i.e., indica-dominant) genotypes.


1663775604752

There was almost a 3-fold increase in DW (dry weight) over the 135 to 1430 μmol·m-2·s-1 APPFD range in the present study, although 90% of the maximum increase in DW was attained at an APPFD of only ≈ 900 μmol·m-2·s-1.

In contrast, plants were smaller at ≈ 900 vs. 600 μmol·m-2·s-1 but had ≈ 15% higher DW and ≈ 6% thicker stems (i.e., ≈ 13% higher cross-sectional area).

Since the number of nodes saturated at relatively low LI, a canopy-level PPFD target of about 900 μmol·m-2·s-1 may be most appropriate for producing robust but not overly compact plants while also minimizing lighting-related energy and infrastructure costs. Although not as common in commercial settings, production facilities that target more open plant architecture and greater energy conservation may opt for canopy-level PPFD target of ≈ 600 μmol·m-2·s-1.

Few contemporary recommendations suggest exposing vegetative cannabis plants to PPFDs higher than 800 μmol·m-2·s-1 in indoor production systems. The current study demonstrates that vegetative cannabis can be exposed to substantially higher LIs (than commonly-used in the industry) with positive morphological outcomes that can prime plants for the transition into the flowering phase.


Note: "Blurple light" spectrum LEDs used for study!

1663776230137


F igure 1. Relative spectral photon flux distribution of blue (B) and red (R) LEDs used during the propagation and vegetative stages
I would recommend keeping in mind that multiples studies have shown an increase in photosynthetic activity, as in higher rates of photosynthesis, when plants are exposed to IR along with normal PAR range lighting. The overall photosynthetic efficiency was higher in plants that had IR included in their spectrum, than plants that didnt.
Since this study was conducted purely with LEDs, I wonder if those intensities could be reduced with the addition of some heat lamps or IR diodes.
 
Top Bottom