Hey all,
You guys have any info on suggested DLIs of a CO2 enhanced autoflower during different stages of it’s life? Perhaps any links to studies or books that talk about the subject? I’m aware the DLI of any plant is going to be growth stage, condition, and strain dependent, but I’d be happy to learn more about generalities of the function or specific values in particular scenarios.
I’m currently running an autoflower in flower with passive organic CO2 supplementation at a DLI of 45. I tried contacting the breeder but they wouldn’t give me any information in regards to growing conditions, so I am left wondering about optimal DLI (among other things). Since it is infeasible for me run a series of controlled tests where I implement various lighting schedules, intensities, and conditions as see which group grows best, I’d like to know how to determine the best DLI schedule for my plant/conditions.
I assume there should be a scenario where all other factors have been optimized and an increase in DLI would provide no further improvements to growth. This point throughout all stages of growth is the line that I would like to find. Is there a comprehensive guide that I can follow? Is there a way that I can easily determine this empirically? Should I just increase the DLI until I see an issue with the plant and then back off? I imagine this method would probably only produce decent yields the second time around due to all the stress in the first grow. I’m open to any input you guys have.
Also, am I correct in assuming that so long as you don’t burn a plant with too high of a PPFD that equal DLIs are equivalent regardless of day length/intensity?
At what ppm is your ” passive organic CO2 supplementation” ?
Unfortunately I am still working on a CO2 sensor and cannot provide a reading of current levels.
I just asked because it will have an overall effect of the leaf surface temp and in turn transpiration and in turn heat generated from the light which in turn is influenced by the length of time running, which is the answer to the question of DLI. Just incase anyone wonders how I got there.
I’ve been guilty of confusing light intensity with DLI, which are different measurements. My mind can 100% appreciate your question but I think Coach Steve may be on to it when he suggests that this may be a little bit of over thinking it. In smaller environments, the plant will give you indicators of droop if it is getting to many hours aka too much DLI.
I think the thing I would be thinking of considering balance, would be the trade off between additional hours of light versus normal hours of darkness in order to build a bigger and healthier root system.
I’m sorry to not have an actual answer, but I fear it is looking for something so technical that a whole host of other variables would need to be match before it could apply to your plants. Sometimes real world scenarios are far from the lab perfect conditions.
I’m aware of at least the basic implications of a heat and CO2 relationship with cannabis, which is why, without an actual co2 reading, I am aiming for the high side of normal for temperatures (28C).
I’m not confusing those concepts if that’s your implication. I’ll look for the droop and then dial back in veg, seems to be what most people are recommending to get an idea of the right amount.
I’m also finding the public opinion is that 4 hours for the processes that occur during lights out is sufficient, but I’d like to know your thoughts. So assuming I don’t fry the plant with too high of a PPFD and give it enough time for root growth, etc. at night, I should have quite a bit of room to play around with DLI.
By looking for a way to determine the best value for a particular variable I am able to deduce other problems that might be bottlenecking growth and work on improving these factors, and be able to capitalize on these improvements by bringing up the original variable to match. This is not overthinking it, this is how you optimize a system. And guess what. Labs exist. So there is no reason one cannot not emulate those conditions IMO.
Not implying you were confused about PPFD and DLI, just saying exactly what I meant, I’ve confused the two in the past.
To the degree you are attempting to build this grow, on a commercial level, I would think it is rational but on a home level, personal cultivation in a small tent, my opinion changes because the amount of difference will be minimal on the small scale. When replicated over large footprints, small variables and differences in results add up to large numbers.
To emulate lab conditions, you will be spending more and go further than 99% of home growers. Again, if it were commercial you are dealing with different rule sets. So are you a home grower or a commercial grower?
Many people run an 18/6 or a 20/4 cycle during veg and that seems adequate to give the roots time to grow in the dark and enough DLI during lights on.
Seems like a lot of overthinking for an indoor grow. There are maps of regions to help people know if they need supplemental lighting, but Indoors, light is constant. Since there are variables in genetics and how much light they can use each day, it’s simple enough to let the plant tell you what the limit is and adjust accordingly.
You’re growing autoflowers with ambient co2, so I guess you want to be efficient with power usage..?
I’m missing the importance of having a number here. There are too many variables to consider. The environment at the roots is a big one.
Sorry I didn’t truly answer your question or offer any links, but you put all that effort into the post and received no thoughts. I’m saying what everyone is thinking.
My goal is optimal THC production whether that be through bulk mass yield or through concentration in the product and the assumption is that this is accomplished by providing ideal conditions for growth throughout the plant’s life cycle. Power usage is of no concern to me. So you are suggesting erroring on the high side of light exposure and dialing back when you see signs of distress and that these threshold DLIs may not be applicable to another plant even if grown from similarly bred seeds? So in a scenario where there are multiple plants in the same environment you would likely dial back DLI to the level where the most susceptible plant would not be effected.
So this begs the question of how much room is there between the point where no additional light exposure would be useful to the plant and the point where additional light would cause issues with the plant. Is there plenty of room to overexpose a plant without hurting it? Is overexposing until you find issues each grow really the preferred method?
The importance of having a number (or a graph/function rather) is so that I can provide the best amount of light to the plant and not hurt it by proving too much. It seems crazy to me to have to damage a plant just to find how much light it can take every single grow, repeatedly throughout the prosses to find max light and it also seems crazy to grow with anything less than optimal stimuli. I’m referencing a scenario where the roots are in the best environment they can be in.
I’m not at ambient CO2 levels as I have a CO2 producing culture in the system but unfortunately I am still working of a CO2 sensor and cannot provide a reading of current levels.
Ok obviously there could be economic constraints to not growing optimally, but you know what I mean.
Ah sorry I misinterpreted your co2 setup.
You can damage the plant by prolonged, extreme light intensity, but that is not how you determine the plant dli.
I’m really not qualified to point you in the direction you want to go, but I can share my opinion on THC production and it’s not related to dli. By week 8 the plant is focused on producing secondary metabolites and this is the stage to focus on for increasing these numbers and just as importantly, on minimizing volatilization of these compounds.
You can argue less light ends with more THC.
There are tricks a lot of growers use to get an immediate increase in some secondary metabolites by ways of mimicking nature. For example, if an herbivore starts munching on leaves the plant will have an immediate and sometimes delayed response to defend itself. The defense mechanisms are what we enjoy in the finished product, so some growers will use certain stress techniques. Not all plants react the same, but there is science behind the methods.
The game doesn’t stop there, during the dry more than half of the volatile secondary metabolites like terpenes will be lost. During the cure you continue to lose terpenes, but also increase other metabolites by more than 100%. I’m sorry I don’t know these off the top of my head, but I’ll check my bookmarks and link a reference I have.
So, my point is that when we are talking about light, or DLI, we are really talking about plant growth. During ripening, light is to be balanced for plant metabolism while not over doing it to cause excess evaporation of volatile oils and compounds. That’s where you make your money.
I found this study to be very informative in terms of molecules and terpenes. There’s a section that notes how terpenes and the entourage effect is what determines the type of high. THC is a psychoactive compound, but terpenes create the full effect.
https://www.mdpi.com/1420-3049/25/24/5792/htm
That’s interesting, I hadn’t considered the evaporation of these compounds from light exposure while the plant is still alive. I’ll look more into metabolite modification, perhaps that probably more of what I’m after in this stage.
Thanks for the paper recommendation, looks like this will be an interesting read.
No problem. And you are right, when the plant is still producing secondary metabolites [while still living], you can argue they are readily replaced.
Just to be clear, those are my opinions based off of what I know to this point, but I’m still only applying the knowledge and taking mental notes.