Let there be light - What's the best grow lights, growing ?

[acespicoli]

Let there be light ​

nugzz

What is PPFD and DLI

docs.google.com

OK SO REALIZING THAT DUE TO GROWTH STAGE YOU MAY USE DIFFERENT LIGHTS
THE QUESTIONNAIRE - SURVEY ALLOWS MULTIPLE CHOICES, TELL ME ABOUT YOUR CHOICES.
MAYBE REFERENCE YIELDS GRAMS/WATT ETC LINK SOME THREADS WHATEVER YOU LIKE
AFTER YOUR VOTE IS CAST ALL RESULTS WILL APPEAR

Grow light - Wikipedia

en.wikipedia.org

Light Quantity​

Light quantity refers to the amount of light a plant requires each day for optimal growth. Historically, light quantity was expressed in units of W m−2, lumens, or lux. While these units are useful in energy calculations, W m−2, or in human lighting (lumens and lux), plant scientists now prefer to measure the photosynthetic photon flux density (PPFD), in units of μmol m−2s−1. PPFD is an explicit measure of the quantity of photons hitting a surface per square meter per second, a more accurate way to measure how plants interact with photons.[35]

Another useful way to measure light quantity is through the daily light integral, or DLI. The DLI takes into account the PPFD and the total number of hours a plant is exposed to that PPFD to get the total quantity of photons per day, in units of mol m−2d−1. The equation for converting PPFD to DLI, assuming constant PPFD, is below.[36]

DLI (mol m−2d−1) =0.0036 * PPFD (μmol m−2s−1) *Hours of Light

HOPEFULLY WE CAN ALL AGREE ON PPFD ?
IF NOT A CONVERSION CALCULATION WILL BE NEEDED FOR THAT DISCUSSION
PERSONALLY IM INTERESTED IN THE BEST

• SEEDLING/CLONE
• VEG
• FLOWER

THOSE WOULD BE THREE DIFFERENT BULB CHOICES


THIS FROM #ICFAM VENDOR @Mars Hydro Led TO HELP KICK THINGS OFF

How Much PPFD For Indoor Plants In Each Growth Stage

How do you know that indoor plants are given the optimal amount of artificial led lighting? By PPFD figures. To get better color, healthier leaves, and higher yields, indoor growers need to know how m

www.mars-hydro.com

1. PPFD for Weed​

Weed requires 16 hours of light during their vegetative stage and 12 hours at the flowering stage. As mentioned earlier, a grower can either supplement CO2or not.

For regular weed growing, the PPFD for seedling stage is 100-300 µMol/m2/S; the PPFD for vegetation stage is 400-600 µMol/m2/S, and the PPFD for flowering stage is 800-1,000 µMol/m2/S.

When the CO2 supplement in weed growing, the PPFD in the
seedling stage is 100-300 µMol/m2/S, while the
vegetative stage requires 600-1000 µMol/m2/S PPFD and 400-800 ppm CO2.
flowering stage requires 1,000-1,500 µMol/m2/S PPFD and 800-1400 ppm CO2.
(SCIENCE PAPERS COMING)

It is best to consult an expert grower before supplementing carbon dioxide when growing indoors.
Sometimes, the increased inputs due to the use of CO2 may not justify the outputs you desire.

List of light sources - Wikipedia

en.wikipedia.org

OK THATS THE THREAD INTRO,
WELCOME - HOPE TO GATHER SOME WELL GROWN CANNABIS SHOTS AS WELL

 

[Creeperpark]

Let there be light ​

View attachment 18959585
nugzz

OK SO REALIZING THAT DUE TO GROWTH STAGE YOU MAY USE DIFFERENT LIGHTS
THE QUESTIONNAIRE - SURVEY ALLOWS MULTIPLE CHOICES, TELL ME ABOUT YOUR CHOICES.
MAYBE REFERENCE YIELDS GRAMS/WATT ETC LINK SOME THREADS WHATEVER YOU LIKE

Grow light - Wikipedia

en.wikipedia.org

Light Quantity​

Light quantity refers to the amount of light a plant requires each day for optimal growth. Historically, light quantity was expressed in units of W m−2, lumens, or lux. While these units are useful in energy calculations, W m−2, or in human lighting (lumens and lux), plant scientists now prefer to measure the photosynthetic photon flux density (PPFD), in units of μmol m−2s−1. PPFD is an explicit measure of the quantity of photons hitting a surface per square meter per second, a more accurate way to measure how plants interact with photons.[35]

Another useful way to measure light quantity is through the daily light integral, or DLI. The DLI takes into account the PPFD and the total number of hours a plant is exposed to that PPFD to get the total quantity of photons per day, in units of mol m−2d−1. The equation for converting PPFD to DLI, assuming constant PPFD, is below.[36]


HOPEFULLY WE CAN ALL AGREE ON PPFD ?
IF NOT A CONVERSION CALCULATION WILL BE NEEDED FOR THAT DISCUSSION
PERSONALLY IM INTERESTED IN THE BEST

• SEEDLING/CLONE
• VEG
• FLOWER

THOSE WOULD BE THREE DIFFERENT BULB CHOICES


THIS FROM #ICFAM VENDOR @Mars Hydro Led TO HELP KICK THINGS OFF

How Much PPFD For Indoor Plants In Each Growth Stage

How do you know that indoor plants are given the optimal amount of artificial led lighting? By PPFD figures. To get better color, healthier leaves, and higher yields, indoor growers need to know how m

www.mars-hydro.com

1. PPFD for Weed​

Weed requires 16 hours of light during their vegetative stage and 12 hours at the flowering stage. As mentioned earlier, a grower can either supplement CO2or not.

For regular weed growing, the PPFD for seedling stage is 100-300 µMol/m2/S; the PPFD for vegetation stage is 400-600 µMol/m2/S, and the PPFD for flowering stage is 800-1,000 µMol/m2/S.

When the CO2 supplement in weed growing, the PPFD in the
seedling stage is 100-300 µMol/m2/S, while the
vegetative stage requires 600-1000 µMol/m2/S PPFD and 400-800 ppm CO2.
flowering stage requires 1,000-1,500 µMol/m2/S PPFD and 800-1400 ppm CO2.
(SCIENCE PAPERS COMING)

It is best to consult an expert grower before supplementing carbon dioxide when growing indoors.
Sometimes, the increased inputs due to the use of CO2 may not justify the outputs you desire.

List of light sources - Wikipedia

en.wikipedia.org

OK THATS THE THREAD INTRO,
WELCOME - HOPE TO GATHER SOME WELL GROWN CANNABIS SHOTS AS WELL

I love mixing different lights to find the perfect light spectrum. Plus using combos is a great way to heat the grow. I mix HPS with LEDs.

 

[acespicoli]

average photosynthetic photon flux density (APPFD)
Photosynthetic photon flux density (PPFD):
the number of photons in the 400- to 700-nm waveband incident per unit time on a unit surface.

Photometry (optics) - Wikipedia

en.wikipedia.org

Cannabis cultivation - Wikipedia

en.wikipedia.org

Front. Plant Sci., 10 May 2021

Sec. Crop and Product Physiology

Volume 12 - 2021 | https://doi.org/10.3389/fpls.2021.646020

 

[acespicoli]

PLoS One. 2019; 14(3): e0213434.
Published online 2019 Mar 18. doi: 10.1371/journal.pone.0213434

There is some chatter about T5 production coming to an end...hopefully just a rumor like digital tv antennae
Just looked up not long ago and they are close to LED on power usage PPFD/WATT
I really like the way they run super cool and stack close inter nodes on plants
You can put leaves directly against a T5...
@Creeperpark also nice to add on sides get light under plants
Those old 4' two bulb shop lights are getting hard to find, there close to my heart
and we had those old E27 100 watt plant bulbs back in the day

 

[acespicoli]

Daily light integral - Wikipedia

en.wikipedia.org

Plants (Basel). 2023 Mar; 12(5): 1061.
Published online 2023 Feb 27. doi: 10.3390/plants12051061

 

[acespicoli]

LEDs Versus HPS Lamps
The ideal lighting system for cannabis growth is difficult to
determine as both LEDs and HPS each have their respective
advantages (Viršilė et al., 2017). For large scale of production
with uniformly spaced plants, HPS provides a broader uniform
light distribution that can cover a larger area of production
than LEDs (Nelson and Bugbee, 2014). However, LEDs can
be optimized to specific production conditions by controlling
periodicity, quantity, and spectrum of the light provided (Pinho
et al., 2007). LEDs allow high-density production systems to
have a focused spectral quality that can maximize radiation
transfer to plants (Nelson and Bugbee, 2014). Their low heat
emission allows them to be placed in the plant canopy for
maximum cannabinoid yields (Viršilė et al., 2017; Hawley, 2018).
Based on the cost analysis, photon efficacy, and capital costs
of fixtures per photon delivered, it has been determined that
LED fixtures cost five to ten times more than HPS fixtures,
and that current, efficient fixtures available in the US have
nearly identical efficiencies of 1.66–1.70 μmol J−1 (Nelson and
Bugbee, 2014). The same study showed that both technologies
have relatively low long-term maintenance costs. Dutch and
Danish LED fixtures with efficiencies of 2.2–2.4 μmol J−1 are
available in Europe, whereas the newest HPS lamps (1,000 W)
reach up to 2.1 μmol J−1, indicating that LEDs are fully
implementable on a commercial scale (Ouzounis et al., 2015)

Front. Plant Sci., 28 March 2019

Sec. Crop and Product Physiology

Volume 10 - 2019 | https://doi.org/10.3389/fpls.2019.00296

Best 1000w Double Ended (DE) Bulb & Lamp Comparison Review & Test Including: Philips, Gavita, Ushio, Hortilux, and More.​

• Oct 11, 2016

Best 1000w DE lamp test​

BEST 1000W DE HPS BULB COMPARISON CHARTS PDF

Hey everyone, Nate from Growers House here, and today we are doing the next comparison which is our 'Best double-ended 1000 watt HPS test.' We're doing that today because Hortilux just came to market with their new Hortilux DE HPS 1000 Watt and we really wanted to see how it stacks up against the big players in the industry. So, we brought out eight different DE HPS 1000 watt bulbs, the most popular ones in the industry, and we're gonna see how they do against each other. So let's check out your intensity spectrum and run some analysis on them. Let's jump into it!
Ushio Double Ended DE Enhanced Performance Pro-Plus HPS Lamp 1000w
$68.00

Spectra of the best 1000w de lamps​

Okay, so here the test results for the best 1000w DE lamp test. Looking at the spectra of these different light bulbs you'll notice that they all overlap each other extremely well. The only time you can actually notice that there's any difference in the spectra of these grow lamps is the minor differences in intensity between them at different wavelengths. Since all HPS lamps have a very similar chemical makeup (sodium and other trace elements), we expect them to be at least somewhat similar, so no surprise here.

PAR charts over 3' x 3' of best 1000w de lamps​

Now you can see you know how we did our testing. We essentially put each grow lamp above our 3 ft x 3 ft footprint, and we went out to3 ft x 3 ft just because we wanted enough points to get a statistically significant reading of the photosynthetically active radiation (PAR) that the light bulbs are giving off. PAR is effectively the intensity between 400 to 700 nanometer light wavelengths, which is the range of the wavelength that plants use best to photosynthesize. So in taking the sum of the intensities and all these points within a three by three area we were able to glean quite a bit of statistical data.

bar graphs of light intensity of 1000w DE lamps​

So let me pull it up right now, so here's a chart that shows off you know, what we think is probably the best number to focus on to figure out what lamp really did best in this test which is the 'Sum of all PAR over 3' x 3' Footprint', which means taking every point that we measured and adding them together. The 1000w DE lamp that performed best in testing was the light that turned out to give us the most amount of light using the same ballast and reflector was the Philips Green Power 1000 watt DE HPS.
Our hypothesis was that the Philips 1000w DE lamp would probably do best because we've heard from other lighting manufacturers who have done similar testing using equipment that's far superior to ours--such as goniophotometers--saying that the Phillips DE, with some of its patented ignition technology, is producing the best 1000w DE lamp out there.

statistics of the best 1000w de lamps​

So we recorded the total par of 18,852 and we some of them up, but that said there are four lights that we felt performed very well. The Philips Green Master Power 1000 watt DE HPS being number one and then it looks like the Gavita Pro Plus 1000w DE HPS Lamp and the Ushio DE Enhanced Performance Pro-Plus HPS 1000w Lamp, and then the Genesis. All four of those 1000w DE lamps are actually within about 1.5 percent of each other. We're not talking about drastic differences--I would consider all those bulbs very good. If you want the best bulb out there, it's the Phillips 1000w.

Jumping into the lights that we're not in the top four, one of the one of the ones that we were hoping was going to be up there Hortilux 1000w DE lamp. It didn't quite make it with their first DE iteration. Looking into maybe what the most bang for your buck, you may want to go with the Nanolux MaxPar DE HPS 1000W Lamp. It did pretty well coming in just behind those first four, and at a cost of about two-thirds the price most the lamps on here.
Another interesting note is the difference between the best lamp and the worst lamp was about 7.4%. I would say that's definitely going to have a meaningful difference in your crop yield, especially if you're a commercial grower. In our final thoughts, it seems the differences in lamp quality is not just marketing hype. There are true differences in 1000w DE lamp performance. Think about your priorities when shopping around overall output vs budget, but if you're growing high value crops, it seems the Philips 1000w DE is going to give you the most output of your buds and flowers. Happy growing everyone

 

[dogzter]

You left out the sun.

 

[acespicoli]

thanks brother for catching me slipping

 

[acespicoli]

A major challenge in breeding new cannabis and hemp cultivars lies in the poor understanding of the phylogeographic structure and domestication of cannabis. Zhang et al. described three haplogroups, from wild and domesticated populations or cultivars, which were associated with distinct high-middle-low latitudinal gradient distribution patterns and consistent with the existence of three cannabis subspecies (C. sativa subsp. ruderalis, sativa, and indica). Day-length was found to be the most important factor influencing population structure. The paper also suggests that there are multiregional origins for domesticated cannabis and that cannabis probably originated in a low-latitude region.

Baghlan, AF Climate Zone, Monthly Weather Averages and Historical Data

Climate of Baghlan, Afghanistan. Information regarding Baghlan climate zones and historical climate data including temperature and precipitation.

weatherandclimate.com

(how to control altitude UV intensity atmospheric gas levels???)

Bluefish User Guide​

Getting Started​

• Initial hardware setup
• Installing the app
• Connecting the app to the controller (BlinkUp)

Lighting Controller​

Configure lighting channels:

• PWM Mode
• Display Name
• Display Color
• Pendant Time Shift
• Minimum Dimming Level

Configure lighting options:

• Morning/Midday/Evening/Night
• Natural Sun
• Clouds
• Storms
• Lunar Cycles
• Sunrise/Sunset Dynamic Photoperiod
• Photography Mode
• Scene Timer

Initial Hardware Setup​

1. Configure output voltage
Your Bluefish controller is configured to output 10V on its lighting output channels by default. If you are using the device with drivers that require 5V (Mean Well LDD drivers, for example), this could damage your drivers.

To change your output voltage:

• Disconnect from power and remove Imp card from device.
• Remove the 4 screws in the back cover of the device.
• Remove the back cover and circuit board.
• Remove the 2 screws holding the circuit board to the cover.
• Move the adjustment jumpers to the required position. These are located on the back of the circuit board, and there is one jumper for each channel. Gently pull the jumper straight out from the circuit board, and place it in the new position. Do not use any tools to remove the jumpers, as they can be easily damaged. As indicated, the left position is for 5V, and the right position is for 10V.
• Replace circuit board and back cover.

Installing the App​

• Search for “Bluefish” in the iOS App Store on your iPhone or iPad, or Google Play for your Android device.
• Install the app

Connecting the App to the Controller (BlinkUp)​

• Open the app, and tap “Register a New Device” at the login screen
• Enter the required fields to complete registration
• Select your WiFi network, and enter your network password (do not start BlinkUp yet)
• Gently insert the Imp card into the slot at the top of the Bluefish device so that it locks into place
• Connect the power supply to the Bluefish device (do not make connection to your lights yet)
• Ensure the light at the edge of the Imp card is blinking, and tap “Start BlinkUp” in the app
• Cover the edge of the Imp card with your mobile device screen for the duration of the BlinkUp process (about 10 seconds). Your mobile device screen will flash rapidly during this process, as it it transmits data to your Bluefish device.
• Once BlinkUp is complete, your Bluefish device will be connected to your login, and accessible remotely with no additional configuration.
• Select an option from the Quick Setup menu to automatically apply settings for common light setups.

Note: If you are outside North America, your WiFi network must be on channel 1-11.

Lighting: Channel Setup​

Each channel is individually configurable to allow use with mixed lighting setups. Ensure your channels are set up correctly before connecting to your lighting product(s).

PWM Mode:
PWM is a digital method of lighting control. Check your lighting specifications to determine whether you need PWM, or 0-10V (PWM off).

Common PWM products: Meanwell LDD drivers, Nano Box fixtures, Bluefish PowerPWM
Common 0-10V products: Mean Well ELN drivers, Kessil A360 pendants

Display Name:
You can assign a custom name to each channel for easy reference. (eg. Blue, White, etc.) This name will be displayed throughout the app.

Display Color:
Set a custom color to represent each channel within the app. This color is for reference only, and has no bearing on the actual light output.

Pendant Time Shift:
You can add a time delay to individual channels. For example, if you had a 3 channel setup (left, middle, and right), you could set Pendant Time Shifts of 60 mins, 30 mins, and 0 mins respectively. This is useful for simulating the movement of the sun with pendant style setups. Paired with Natural Sun mode, this can create a very realistic effect. Test with Fast Forward in the scenes menu.

Minimum Dimming Level:
Some lighting products are not capable of 0-100% dimming. These products will have a minimum level that you can dim them to, and any further dimming will turn them off completely. Without setting a minimum dimming level, this can cause flickering and unintended behavior. You can determine the minimum dimming level for your product using Free Mode in the Scenes menu. Minimum dimming should be set to the lowest percent possible while light remains steadily on.

Lighting: Options​

Morning Start Time: The time of day when your lights will begin to transition from Night Levels to Morning Levels
Morning Length: The length of time between Morning Start time and Midday
Morning Ramp Speed: The length of time it takes to transition from Night Levels to Morning Levels
Morning Levels: The light channel output/color for Morning during clear weather.

Midday Ramp Speed: The length of time it takes to transition from Morning light levels to Midday light levels
Midday Levels: The light channel output/color for Midday during clear weather. Midday Levels are also used throughout the day when Natural Sun is enabled (Morning and Evening Levels are ignored).

Evening Length: The length of time between Midday Levels, and Night Levels
Evening Ramp Speed: The length of time it takes to transition between Midday Levels to Evening Levels
Evening Levels: The light channel output/color for Evening during clear weather.

Night Start Time: The time of day when Night Levels will start
Night Ramp Speed: The length of time it takes to transition from Evening Levels to Night Levels.
Night Levels: The light channel output/color during full moon, and clear weather.

Diagram representing lighting schedule options. Applies when Natural Sun is off.
@dogzter very good point you made!!!

Natural Sun:
When enabled, a smooth dimming bell-curve will be applied using your Midday Levels, Morning Start Time, and Night Start Time. This creates a very natural output. Morning and Evening Levels are ignored in this mode.

Clouds:
When enabled, current weather data is used from your Simulated Location to create cloud patterns by applying dimming to your light output. Partly cloudy, mostly cloudy, haze, overcast, and rain conditions all produce unique cloud patterns with varying density, speed, and dimming.

Storms:
When enabled, thunderstorms with lightning are simulated when your Simulated Location’s current weather conditions match. Lightning color should be set under Special Settings, and Clouds should be enabled for proper effect.

Lunar Cycles:
When enabled, dimming will be applied to your Night Levels to match the moon illumination for your Simulated Location.

Sunrise/Sunset (Dynamic Photoperiod):
When either or both of these options are enabled, your photoperiod (day length) will match that of your simulated location. This changes daily, to simulate the natural variance of the day length throughout the year.

• Option A: To have a variable sunrise time, but end at your Night Start Time, enable Sunrise only.
• Option B: To have a variable sunset time, but start at your Morning Start Time, enable Sunset only.
• Option C: To use the sunrise and sunset times from your Simulated Location directly, enable Sunrise and Sunset (not recommended).
• Option D: To only use your manual settings for sunrise/sunset, disable Sunrise and Sunset.

If you enjoy your tank mainly in the evening, we recommend option A. If you enjoy your tank mainly in the morning, we recommend option B.

Photography Mode:
Photography mode is a way to quickly apply pre-set light levels for taking photos. Adjust the levels in settings, and apply from the Scenes menu.

Scene Timer:
The Scene Timer prevents accidentally leaving your lights in Free Mode or other Scene. After the timer expires, the normal lighting schedule resume






For the 43 hemp populations originating from China [25 wild populations (W) and 18 domesticated cultivars (L and B)] (Table 1, Figure 1), the sampled regions throughout China spanned an area from 50.25° to 23.36° N and from 79.44° to 126.08° E, with an altitude span from about 50 m above sea level in Anhui (C224) to 3,700 m in Tibet (MK).

Figure 1. Geographic location of the 43 populations of Cannabis analyzed in the present study and haplogroup distribution patterns of Cannabis (see Table 1 for population codes); population codes in black represent the wild samples and blue ones are the domesticated accessions. (B) The haplotype network generated from the 25 haplotypes of Cannabis; pie chart size corresponds to the sample size of each population (A) or haplotype (B).
Front. Plant Sci., 20 December 2018
Sec. Crop and Product Physiology
Volume 9 - 2018 | https://doi.org/10.3389/fpls.2018.01876

 

[acespicoli]

Should I have added plasma ?

https://www.htgsupply.com/products/agromax-plasma-grow-light-300-watt/

AgroMax 300 Watt Plasma Grow Light​

Plasma. The Sun is made up of burning plasma, which gives Earth its life-giving sunlight. The AgroMax Plasma Grow Light is like a mini-Sun for your grow room. Plants have evolved over millennia to grow under natural sunlight. The AgroMax Plasma light is as close to real sunlight as you can get artificially.

Your plants will love the benefits of the most natural spectrum available indoors, and you will love the benefits of the Plasma light. The 300 watt LEP light source is built tough with Solid State circuitry and no moving parts in a completely sealed housing for reliability. The ultra-reflective aluminum reflector produces an even, square light footprint for excellent coverage over your garden. There is little to no radiant heat from the light source allowing you to place the light closer to the tops of plants without burning them – which increases light intensity for better plant development.

Specifications:​

Wattage: 300 watt
Voltage: 120-240v
Current: 3.3A max (@120v )
Frequency: 50/60 Hz
Dimensions: 21-1/4″ long x 13-3/4″ wide x 6″ high

Product is covered by a 14-day money back guarantee
Offer valid online only. Price at HTG Supply retail locations may vary

SULFUR PLASMA LIGHTING!!!! 100% SUN

Just reading in "Urban Gardener Mag." the March-April edition of this year on p.48 Titled "PLASMA GROW LIGHTS". OR go to http://www.plasma-i.com/ Anyways this looks amazing studies are showing a 60% increase in cucumber weight compared to HPS lights. So not to shabby. Although it will cost...

www.icmag.com

Gavita Plasma + CaseyJones & Chem4D

Almost a new year is on us and what better time to start a thread on the olde Gavita Plasma with the addition of 2 600 blockbusters, this is diary to see if I can hopefully hit GPW, i know theres lots of debate surrounding this but it seems like this is still a decent measure to use. So...

www.icmag.com

 

[acespicoli]

peppers tomato watermelon corn seeds getting ready... focus
time to get the plants started those long leds 2 packs for the win ?
Outdoor veggies planting 100' x 100' outdoor garden
with seedlings anyone growing other stuff this year as well ?

need this to fit 1020 trays and led stiks...
Thanks for stopping by and checking out the thread!

 

[Creeperpark]

You left out the sun.

I love the Sun best of all because it's free and strong. Plus it's been with me for the last 55 years.

 

[CharlesU Farley]

As usual with you, awesome informational posts!

 

[Rocket Soul]

I think the survey is missing Diy Led as its own category; its completely different growing under a standard white led.

Edit: missed the yield question; on our recent cultivars:
Animal cakes: 2880g using 1880w. Super dense nugs and no larf. 36 plants in 10l pots, coco, full Canna line. 9 weeks 1.5g /w
Rainbow Chip: 1200g using 720w. Bit less dense but still great, very nice beercan sized buds. 12 plants, same nutes, 9 weeks, 1.7g/w.

For watts im counting driver watts; same as 600g from a 600w hps comes out 1g/w even though the power supply will draw a bit more; we simply dont have reliable data on full draw. Also note; we are not on full power until a few weeks into flower, plants go in with light tolerance of 8000lux / approx 100ppfd and take a few weeks to push up to 50k lux.

 

[Ca++]

(how to control altitude UV intensity atmospheric gas levels???)

Negative pressure?
A quite physical difference.

Gas composition remains steady to about 70 miles

While the composition is steady, the amount of it changes. It's about two thirds lower, on Everest. The Hindu Kush is about half that.

Still.. My fan isn't going to make you dizzy. To make the Hindu Kush in my bedroom, I would need 30 of them.

I have often wondered that..


Back to the light.

The shorter wavelengths are generally attenuated more, as the lights forced to do more work. Elements of this cooler light at altitude, have been looked at individually in studies of UV and Blue. The overwhelming opinion of which, is a derailment I'm not starting

The angle of light increases towards the ends of the day, and so warms the light. This could be programmed into an overkill lighting rig. It perhaps has parallels to people adding far red. Another element studied individually, with similar outcome.

I see evidence we should track a plants circadian rhythm quite closely, but only as an on/off guide. I have not seen anything to support the notion of peak hours, though I'm open to the idea. As I am to possible light stress techniques. Where perhaps a darker period, sets them up for a brighter one. Though such light pulsing, would require more investment in lighting. So a nice steady illumination is a preferred outcome.

 

[acespicoli]

GWE

Keep the light level down to
50-60 PPFD. Any more that that will stress the clones. When they are rooted, you should increase the light to 80-100 PPFD at first, wait to see some healthy growth, and then increase up to 150 PPFD

Plant	PPFD (µmol/m²/s)	DLI (mol/m²/d)

Cannabis (Flowering) Cannabis	500 – 1050	30 – 40
Cannabis (Seedling) Cannabis	100 – 300	12 – 16
Cannabis (Vegetative) Cannabis	250 – 600	20 – 45

 

[acespicoli]

@Mars Hydro Led

 

[acespicoli]

I think the survey is missing Diy Led as its own category; its completely different growing under a standard white led.

Edit: missed the yield question; on our recent cultivars:
Animal cakes: 2880g using 1880w. Super dense nugs and no larf. 36 plants in 10l pots, coco, full Canna line. 9 weeks 1.5g /w
Rainbow Chip: 1200g using 720w. Bit less dense but still great, very nice beercan sized buds. 12 plants, same nutes, 9 weeks, 1.7g/w.

For watts im counting driver watts; same as 600g from a 600w hps comes out 1g/w even though the power supply will draw a bit more; we simply dont have reliable data on full draw. Also note; we are not on full power until a few weeks into flower, plants go in with light tolerance of 8000lux / approx 100ppfd and take a few weeks to push up to 50k lux.

DIY LED has been added as a poll choice hope to see some fine examples

The Light Stress In Plants​

Gardening Tips Weed Grow Tips Knowledge Center
May 09, 2023 8843 1

Plants are highly dependent on light for their growth and development, as it is essential for the process of photosynthesis. However, both too much and too little light can lead to light stress in plants, which can have detrimental effects on their growth and productivity.By understanding the mechanisms underlying plant responses to light stress, growers and farmers can develop strategies to optimize plant growth and increase crop yields.

---

What Is Light Stress In Plants?​

Light stress in plants occurs when the balance between the energy absorbed by the plant and the energy utilized in metabolic processes is disrupted, leading to oxidative damage, photoinhibition, and reduced photosynthesis efficiency. There are two types of light stress in plants - high light stress and low light stress.
High light stress is a type of light stress in plants that occurs when the intensity of light exceeds the plant's capacity to utilize it for photosynthesis and other metabolic processes. This can cause damage to plant cells, including the accumulation of reactive oxygen species (ROS), which can damage cell membranes, proteins, and DNA. High light stress can also cause photoinhibition, which is the reduction of photosynthesis efficiency due to the inactivation of photosystem II (PSII) in chloroplasts. The severity of high light stress depends on the duration and intensity of light exposure, as well as other environmental factors such as temperature and humidity.
Low light stress is a type of light stress in plants that occurs when the intensity of light falls below the level required for optimal photosynthesis and growth. Under low light conditions, the amount of energy available for plant metabolism is limited, which can result in reduced photosynthesis rates and growth. In some cases, low light stress can cause a decrease in the levels of photosynthetic pigments, such as chlorophyll, which can further reduce the plant's ability to absorb and utilize light energy.

How Do I Know If My Plants Have Light Stress?​

Light stress in plants can manifest in various ways, and there are several signs that can indicate if your plants are experiencing light stress.

1. Yellowing or bleaching of leaves: One of the most common symptoms of light stress is the yellowing or bleaching of leaves, particularly in older leaves. This occurs due to the breakdown of chlorophyll, the pigment responsible for absorbing light energy for photosynthesis.
2. Stunted growth: Plants experiencing light stress may also exhibit stunted growth or slow development, as reduced photosynthesis rates can limit the production of the energy required for growth and metabolism.
3. Reduced yield: If your plants are crops, light stress can also reduce yield by limiting the amount of energy available for the production of fruits or seeds.
4. Leaf drop: In severe cases, plants may shed leaves or other plant parts as a stress response, which can further reduce growth and productivity.
5. Changes in leaf color or shape: Depending on the species, plants may respond to light stress by changing leaf color or shape, such as curling or cupping leaves.
6. Reduced plant vigor: Light stress can also lead to reduced plant vigor, as the plant is not able to produce enough energy for its metabolic processes, including defense against pests and diseases.
7. Changes in leaf position: Plants may change the orientation of their leaves to avoid excessive light exposure. For example, some plants may turn their leaves away from the sun to reduce the amount of light they receive.
8. Leaf scorching: When plants are exposed to high-intensity light, particularly during hot and dry weather, the leaves may become scorched or burnt. This can cause brown or black spots on the leaves, and the leaves may eventually die.
9. Delayed flowering: For plants that rely on photoperiodism to flower, light stress can disrupt the plant's internal clock and delay or prevent flowering.

If you notice any of these symptoms in your plants, it may be an indication that they are experiencing light stress. However, these symptoms can also be caused by other factors, such as nutrient deficiencies or disease, so it is important to carefully consider all possible causes of the symptoms before taking any action.

How To Confirm The Presence Of Light Stress After Noticing The Signs?​

To confirm whether light stress is the cause of the symptoms, you can perform a simple light stress test. This involves exposing a small portion of the plant to higher light intensity than normal for a short period, typically a few hours, and then observing the plant's response. If the exposed area of the plant shows signs of stress, such as leaf bleaching or curling, it may be an indication that the plant is experiencing light stress.

Plant Mechanism Against Light Stress In Plants​

Defense Against High Light Stress​

Can too much light kill a plant? Yes. Therefore, plants have several mechanisms to defend against high light stress, which can help them to maintain their physiological functions and survive under challenging conditions.
One of the most important mechanisms is photoprotection, which involves the dissipation of excess energy as heat, thereby reducing the formation of harmful reactive oxygen species (ROS). Plants can achieve this by increasing the production of carotenoids, such as zeaxanthin and lutein, which can act as photoprotective pigments in the chloroplasts.
Plants also produce antioxidant enzymes, such as superoxide dismutase (SOD), catalase, and peroxidase, which can help to neutralize ROS and protect against oxidative stress. In addition, plants can upregulate the expression of genes involved in stress responses, including heat shock proteins, which can help to repair damaged proteins and membranes.
Another mechanism that plants use to defend against high light stress is the regulation of photosynthesis. Plants can downregulate the expression of genes involved in the light-dependent reactions of photosynthesis, such as those encoding the photosystem II (PSII) reaction center, in response to high light stress. This helps to prevent the accumulation of excess energy and ROS, and can reduce the risk of photodamage.
Finally, plants can also adjust their growth and development in response to high light stress. For example, they may produce smaller and thicker leaves, which can reduce light penetration and increase light absorption efficiency. They may also allocate more resources to root growth, which can help to improve water and nutrient uptake. You can also tell by this (size of leaves vs. normal size) if your plant is under stress.

Defense Against Low Light Stress​

Plants also have several mechanisms to defend against low light stress, which can help them to maintain their physiological functions and survive under conditions of reduced light intensity.
One of the primary mechanisms is the regulation of photosynthesis. Plants can increase the expression of genes involved in the light-dependent reactions of photosynthesis, such as those encoding the photosystem I (PSI) reaction center, in response to low light stress. This can help to increase the efficiency of energy capture and utilization, and can improve the rate of carbon fixation.
Plants can also adjust their growth and development in response to low light stress. They may produce larger and thinner leaves, which can increase light interception and maximize light absorption efficiency. They may also allocate more resources to shoot growth, which can help to increase the surface area available for light capture. The same as before, you can tell if your plants are under low light stress by their leaves' sizes.
In addition, plants can produce specialized pigments, such as anthocyanins and flavonoids, which can act as light-absorbing molecules and protect against oxidative stress. These pigments can help to enhance the efficiency of light capture and utilization, and can also serve as antioxidants to protect against damage from excess ROS.
Finally, plants can also adjust their metabolism in response to low light stress. They may increase the production of storage compounds, such as starch and lipids, which can help to store excess energy and support growth and development when light levels are low.

How To Prevent Light Stress?​

Preventing stress is always easier than trying to manage its effects after the fact, so take the time to provide your plants with the best possible growing conditions. We listed several bullet points in the following to take care with when growing indoor plants.

• Provide optimal light intensity: Can LED lights burn plants? Yes, they do when you offer the wrong intensity of light for your plants, although LEDs are cool enough to run. To learn the right amount and intensity of light for your plants, please refer toHow Much PPFD For Indoor Plants In Each Growth Stage.
• Control light duration: Make sure to provide the appropriate amount of light and dark periods for your plants.
• Monitor temperature: High temperatures can increase the risk of photodamage, while low temperatures can exacerbate low light stress.
• Provide proper nutrition: Plants need appropriate nutrition to maintain their physiological functions and defend against stress.
• Avoid overwatering: Overwatering can lead to waterlogging and reduced oxygen availability in the soil, which can exacerbate the effects of light stress.
• Provide proper ventilation: Proper ventilation is important for maintaining optimal temperature and humidity levels, as well as for reducing the risk of disease and pest infestations.
• Gradually acclimate plants to high light intensity: If you are moving plants from a low light environment to a high light environment, it is important to acclimate them gradually to prevent photodamage. Start by providing the plants with a lower light intensity and gradually increase the light intensity over time.

How To Fix Light Stress In Plants​

Fixing light stress in plants requires identifying the specific cause of the stress and implementing appropriate corrective measures. Here are some tips on how to fix high light stress and low light stress in plants:

Fixing High Light Stress:​

1. Move the plant to a shadier location: If the plant is receiving too much light, move it to a location with lower light intensity, or provide shading materials such as shade cloth or curtains.
2. Reduce light intensity: If the plant is receiving too much light from artificial sources, you can reduce the light intensity by raising the hanging height of the light fixture, dimming down the light, or changing to a lower wattage bulb.
3. Increase humidity: High light intensity can increase evaporation and dry out the plant, so increasing the humidity around the plant can help to reduce the stress. You can use a humidifier or place a tray of water near the plant to increase humidity.
4. Prune damaged leaves: If the plant is showing signs of photodamage, prune the damaged leaves to prevent further damage and allow the plant to redirect its energy towards healthy growth.

Fixing Low Light Stress:​

1. Move the plant to a brighter location: If the plant growing outdoors is not receiving enough light, move it to a location with more natural light, or provide artificial lighting to supplement the natural light. If the plant growing indoors is not receiving enough light, hang the lighting fixture closer or dim up the lighting.
2. Adjust light duration: If the plant is not receiving enough light duration, adjust the light schedule to provide more light during the day or extend the light period using artificial lighting. But we do not recommend using this way to fix lighting stress because plants have their own rhythm and if you change it other problems will arise.
3. Fertilize: If the plant is experiencing low light stress due to nutrient deficiency, fertilize the plant with a balanced fertilizer to provide essential nutrients for growth.
4. Prune to improve air circulation: If the plant is growing leggy and stretched out due to low light, prune the plant to promote bushier growth and improve air circulation around the plant.

Remember to gradually acclimate plants to any changes in light conditions to prevent additional stress. In some cases, it may take time for the plant to recover from light stress, so be patient and continue to provide appropriate growing conditions to promote recovery.

In Conclusion​

In conclusion, light stress is a significant issue that can affect the growth, development, and overall health of plants. High light stress and low light stress can have detrimental effects on plant tissues, which can lead to reduced growth, productivity, and even death. However, with proper care and attention, it is possible to prevent and mitigate the effects of light stress in plants. By providing appropriate light intensity and duration, and taking steps to reduce stress factors such as temperature, humidity, and nutrient availability, you can help your plants to thrive and achieve their full potential. Regular monitoring, timely interventions, and a proactive approach to plant care can go a long way towards preventing and addressing light stress in your plants, and ensuring that they continue to flourish and provide beauty and benefits for years to come.


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Found this @Mars Hydro Led website
light off period was discussed earlier, moving from 24hr constant veg

 

[acespicoli]

Indoor grown cannabis yield increased proportionally with light intensity, but ultraviolet radiation did not affect yield or cannabinoid content

Cannabis (Cannabis sativa) flourishes under high light intensities (LI); making it an expensive commodity to grow in controlled environments, despite its high market value. It is commonly believed that cannabis secondary metabolite levels may be enhanced ...

www.ncbi.nlm.nih.gov

Front Plant Sci. 2022; 13: 974018.
Published online 2022 Sep 27. doi: 10.3389/fpls.2022.974018

Discussion​

Two of the dominant phytogenic factors that affect profitability in commercial drug-type cannabis production are marketable yield (i.e., the mass of mature, unfertilized female inflorescences) and the secondary metabolite composition (i.e., concentrations of cannabinoids and terpenes) in these marketable tissues. A primary objective of this study was to explore proof of concept for the potential for UV radiation treatments for increasing cannabinoid content, particularly THC, in a modern indoor-grown cannabis genotype with a relatively high THC content. The genotype used in this study was typical of Type-I (i.e., drug-type) cannabis (de Meijer et al., 1992); with >20% THC (i.e., ≥200 mg g–1) and low CBD in the inflorescence tissue. A low amount of cannabigerol (CBG, the chemical precursor to both THC and CBD) was detected. The ratio of T-THC to total CBG (T-CBG) was ≥17, indicating that the majority of the cannabinoid production in this cultivar had reached the targeted end point. There was also no cannabinol (CBN) – a natural THC breakdown product – detected in any sample (data not shown) which, along with the high ratio of T-THC to T-CBG, indicated that the plants were near peak maturity at harvest (Aizpurua-Olaizola et al., 2016).

Increasing light intensity proportionally increases yield​

Many (interrelated) environmental parameters can be optimized in order to maximize yields, including temperature, humidity, CO2 concentration, and fertility. However, in indoor cultivation environments, LI is one of the most prominent and expensive input parameters under the complete control of the cultivator (Mills, 2012). The optimum LI in a given production scenario will depend on many economic factors, but the responses of modern cannabis genotypes’ yield and secondary metabolite composition to LI are key input factors that can only be elucidated experimentally. Compared with the 600 μmol m–2 s–1 treatment, increasing the PAR exposure by 1.6 times (i.e., 1,000 μmol m–2 s–1) increased inflorescence dry yield by the same magnitude. This implies that, for yield responses in this trial, the cannabis plants growing under 1,000 μmol m–2 s–1 were still on the linear phase of the light response curve (i.e., still operating at maximum quantum efficiency). This is also supported by the linear yield responses to increasing LI up to 1,800 μmol m–2 s–1 reported in Rodriguez-Morrison et al. (2021a). A linear yield response to a range of LIs that exceeds normal production levels (Potter and Duncombe, 2012), confers a relatively reliable and easily interpreted basic model for how cannabis yield responds to changes in LI. For example, a simple regression of the mean DWf at the three tested PPFD levels (i.e., for calculating slope) in the present study predicts that every additional 100 μmol m–2 s–1 of daily PAR will increase yield by 4.6 g/plant (i.e., 51 g m–2 at the present study’s planting density).
Although not statistically significant in this trial, the harvest index (HI, i.e., proportion of marketable aboveground biomass) also rose with increasing LI, similar to Rodriguez-Morrison et al. (2021a). This trend has also been observed in other species, but the rate of increase in cannabis HI was approximately 4-fold higher than in indoor-grown wheat (Bugbee and Salisbury, 1988) over a similar LI range. This serves as further evidence of cannabis’ enormous phenotypic plasticity in response to LI. Higher HI could enhance harvest efficiency by reducing the non-marketable proportion of the biomass, all of which needs to be removed at harvest and disposed (EMCDDA, 2012). Further, since inflorescence tissues have substantially higher cannabinoid contents than other aboveground tissues (Richins et al., 2018), plants that produce proportionally higher inflorescence biomass under higher LI may also increase overall cannabinoid yield. While this was not evaluated in the present study, it is also likely that the increased HI was associated with larger inflorescences and increased floral density, such as reported in Rodriguez-Morrison et al. (2021a). These attributes are generally highly valued by the industry, particularly when the crop production is targeted toward the dry inflorescence market which presently accounts for over 60% of total cannabis product sales in Canada (Health Canada, 2021).

Potential costs and benefits of increasing light levels in commercial production​

The slope of the yield response curve relates to a crop’s phenotypic plasticity to respond to changes in environmental inputs – light intensity in this case – which will of course vary by genotype and production environment (Backer et al., 2019; Zheng and Llewellyn, 2022). Nevertheless, using the present study’s genotype as a proxy, one can estimate the payoff associated with increases in LI. For example, increasing the PPFD by 100 μmol m–2 s–1 increases the total light integral over 45 days by 195 mol m–2. The estimated increase in yield of 51 g m–2 for 195 mol m–2 of additional lighting corresponds to a light use efficiency of 0.26 g mol–1. The energy cost for additional lighting relies heavily on fixture efficacy, light distribution, and local cost of electricity. Most modern horticultural LED fixtures have efficacy values exceeding 2.5 μmol J–1 (i.e., 9 mol kWh–1) (Design Lights Consortium, 2022). If electricity cost was 0.10 $CAD/kWh, the estimated energy cost in this scenario would be approximately 0.042 $CAD/g or an energy use efficiency of approximately 2.4 g kWh–1 (for lighting). The increases in fixture efficacy in modern horticultural LEDs (Kusuma et al., 2020) may explain two-times higher estimated energy use efficiency in the present study vs. estimates from scientific studies in past decades (EMCDDA, 2012). At the current wholesale price for dried inflorescence of 4.00 $CAD/g (Cannabis Benchmarks, 2022), the added electricity cost of increasing yield by increasing LI comprises only ≈1% of the total price, and therefore may make economic sense. However, the costs of additional lighting infrastructure and ancillary costs such as heat management and higher crop production inputs must also be considered when assessing the potential profitability associated with any lighting strategy.

Light intensity did not substantively affect chemical composition​

The lack of LI effects on inflorescence cannabinoid content was consistent with other studies (Vanhove et al., 2011; Potter and Duncombe, 2012; Rodriguez-Morrison et al., 2021a). The lack of LI effects on inflorescence terpene content was also consistent with Rodriguez-Morrison et al. (2021a). Overall, both cannabinoid and terpene yield (i.e., g/plant or g m–2) increased concurrently with increasing inflorescence DW, which may be important for processing cannabis extracts. While many factors are involved in evaluating profitability of adopting a specific production practice, raising canopy-level LI may be an economically feasible way to increase inflorescence and secondary metabolite yield – but not concentration – in indoor cannabis production.

 

[puffin fresh]

Great posts and lots of really interesting papers to read, thanks!