Light studies recommend high intensity: 900 and 1800 mols

effexxess

effexxess

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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


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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).

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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).

Figure 7

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.






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.


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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!

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F igure 1. Relative spectral photon flux distribution of blue (B) and red (R) LEDs used during the propagation and vegetative stages
 
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Homesteader

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Firm believer in this for hybrid. High intensity lighting in veg for pure sativa or close to it is redundant though
 
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Its420anytime

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Graphs mean nothing, like window stickers on vehicles, rarely do they get what's advertised. Who can say they are valid or what product they are pushing. Leds equal intensity, old school bulbs was illumens.
All for what,? Light penatration, canopies.
Proof is in your results or others. 1000s of mediums, soil, no soil, organic, non organic nutes have all produced with great results. Same with lights.
 
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Its420anytime

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Testing of those lights, leds, most are done in pheres, something that a grow room isn't, thus why test in a space that doesn't emulate our grow spaces.
Most guys doing YouTube test have mylar floors, does your grow room have mylar. Do you have mylar ceilings?

How about flat white walls? No tests.
Word of mouth amoung growers us all I need or my experience not to get sucked in.
 
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Its420anytime

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It's just a graph, has no validation. I can make one, does that make it valid. No.
 
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Its420anytime

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What makes the graph valid, 3 peeps writing about it? Seems liked valid question. Just because the window sticker said 40 mpg on the highway doesn't mean we get that.
 
BehindEnemyLines

BehindEnemyLines

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What makes the graph valid, 3 peeps writing about it? Seems liked valid question. Just because the window sticker said 40 mpg on the highway doesn't mean we get that.

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?
 
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Its420anytime

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What or how does heights play into light intensity? Lmao, apparrently nothing, the graph doesn't correlate nothing, apparently some dont read. Posting a graph helped you ask what?
Same question could be asked without posting useless graph that looks like 100 others making other points.

Was probably growing before you were out of diapers, like the graph, dont make it true, believe what you want.
 
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Its420anytime

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Hlg claims to be made in the USA, dont make it true does it. Both drivers, meanwell and invetronics chinese made, 301b, 301h, 301evos, diodes made in 2 chinese factories, lol " trademarked", quantum board, in name only, china owns the patent to the board.
So just cause they say it, don't make it so.
Love my hlg, but hate the phrase made in America, assembled? Who knows
 
BehindEnemyLines

BehindEnemyLines

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What or how does heights play into light intensity? Lmao, apparrently nothing, the graph doesn't correlate nothing, apparently some dont read. Posting a graph helped you ask what?
Same question could be asked without posting useless graph that looks like 100 others making other points.

Was probably growing before you were out of diapers, like the graph, dont make it true, believe what you want.

You have offered ZERO facts to substantiate any of your bullshit claims. It’s obvious you are biased against LED lights and biased towards HID lighting.

Ok, troll. Here’s your hypocritical post from another thread.

It's a forum dont reply if you don't want to help. New guy here, don't have to know. You can see by the friendly responses

Follow your logic and don’t reply if you don’t want to help.
 
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Its420anytime

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You still can't read, as to bull, smell yourself.

Didn't see a question originally posted with graph. Does that graph correlate to any height? No.

Height and intensity are very important. You like to check up on peeps. What's that make you? Lol
 
BehindEnemyLines

BehindEnemyLines

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You still can't read, as to bull, smell yourself.

Didn't see a question originally posted with graph. Does that graph correlate to any height? No.

Height and intensity are very important. You like to check up on peeps. What's that make you? Lol

Your ignorance is truly amazing.

The subject at hand is studying light intensity of up to 900 umols in Veg & 1,800 umols in flower.

We’re looking at LIGHT INTENSITY.
NOT HANGING HEIGHT.
NOT whether lights are “American” or “Chinese” made.

You have not made ONE RELEVANT comment to the SUBJECT at hand. I’m done with you. You’ll resolve yourself. Ignored.
 
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Its420anytime

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First post mentioned 100s of successes of growers with all styles, they work . Biased, on that statement alone in first response, right, you are a troll who needs to read up on people to attack them. That's a fact.

Like old school, it taught me how, love my HLG LIGHT, not their advertising or the gatekeepers. You can Google samsung and diode plants, Google the drivers too, need patent number to?
 
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Its420anytime

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Good thing about ignorance, it can learn, stupid is just plain ole stupid.
Offered nothing, how lights are tested by labs, pheres, how you tube gurus test with mylar 360 top to bottom that gives inflated numbers, kinda like window stickers on mpg that we don't ever accomplish.
 
Aqua Man

Aqua Man

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Good thing about ignorance, it can learn, stupid is just plain ole stupid.
Offered nothing, how lights are tested by labs, pheres, how you tube gurus test with mylar 360 top to bottom that gives inflated numbers, kinda like window stickers on mpg that we don't ever accomplish.
Cut the shit… no place for that attitude here
 
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Its420anytime

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You guys allow your peeps to call others ignorant and trolls. Call others posts bullshit.

Seems like one-way street.
 
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Its420anytime

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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,
 
Aqua Man

Aqua Man

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Supporter
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You guys allow your peeps to call others ignorant and trolls. Call others posts bullshit.

Seems like one-way street.
When your first posts carry the tone of a troll and are insulting to members. Then you asked to stop and you continue its a good indication.

Plain and simple if you have relevant information and want to debate then do so. If you want to continue to argue about it and throw insults with no value to the thread well that wont happen. Drop it and stay on topic. If you cant do that then we have to go a different route.

Debate all you like but keep the persoanl attacks out of it
 

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