Photosynthesis per 100 PPFD

[Rahz]

Playing around with the density to photosynthesis graph I translated averages into a bar graph, percentage of photosynthesis potential x 100s of PPFD.

X is 100, 200, 300 PPFD and so on, y is 0-100% of potential.

 

[robincnn]

Whsts x axis
a little detail would be much appretiated

 

[Scotch089]

X is 100, 200,....

 

[Rahz]

Whsts x axis
a little detail would be much appretiated

Fixed.

 

[coolbreez1]

Shows diminishing returns as PPFD increases, this is why you want 900-1000 PPFD.

 

[captainmorgan]

I think the amount of PPFD needed is dependent on your grow style,I'm getting huge numbers from 529 PPFD over a scrog.

 

[Sxott]

Can I ask where study is that came up with this chart?

 

[Rahz]

It's based on this chart. The mids are probably a bit heavy but it's a close approximation.

 

[Sxott]

Thank you.

Separate lines for 20-40 - Is that the temp in C°

 

[Rahz]

Exactly, around 30 is ideal.

 

[sethimus]

Thank you.

Separate lines for 20-40 - Is that the temp in C°

any serious paper should use si derived units...

 

[SupraSPL]

I like the way you charted that Rahz thank you. From that chart it makes me think 800 is a good compromise unless you are very space constrained.

That chart is cannnabis specific but probably relates to vegetative growth. It makes sense to me to use warm temps (30C) during veg and maybe early flower but I would advise avoiding bud temps of 30C during the second half/two thirds of flowering. It seems to loosen buds, decrease frosting, flavor, potency? and extends flowering time. You might get more weight on the scale due to increased cellulose, but I am not convinced that translates into more trichs/meds and any gains may be erased by the extended flowering time.

 

[PurpleBuz]

It's based on this chart. The mids are probably a bit heavy but it's a close approximation.

View attachment 3480704

I like this chart better

 

[coolbreez1]

I think the amount of PPFD needed is dependent on your grow style,I'm getting huge numbers from 529 PPFD over a scrog.

Well if you look at it you are getting about 75% of potentially even at the mid 500 PPFD. As Supra points out, after about 800 PPFD things start to drop off pretty quick, from 800-1000 you are looking at 20% more light for a return of only 5-10% more yield.

From my own experience, I still get great results with less then 800 PPFD, nice big sticky buds, just a bit fluffy. I am still up in the air about the fluffiness of the buds, in some ways it is nice and makes them burn in a more enjoyable way.

 

[captainmorgan]

Well if you look at it you are getting about 75% of potentially even at the mid 500 PPFD. As Supra points out, after about 800 PPFD things start to drop off pretty quick, from 800-1000 you are looking at 20% more light for a return of only 5-10% more yield.

From my own experience, I still get great results with less then 800 PPFD, nice big sticky buds, just a bit fluffy. I am still up in the air about the fluffiness of the buds, in some ways it is nice and makes them burn in a more enjoyable way.

It may also be somewhat strain dependent. If you count just the COB draw on my set up,my last plant hit about 2 GPW,hard to imagine the plant could produce almost twice that amount on the veg time I give them.

 

[PurpleBuz]

Well if you look at it you are getting about 75% of potentially even at the mid 500 PPFD. As Supra points out, after about 800 PPFD things start to drop off pretty quick, from 800-1000 you are looking at 20% more light for a return of only 5-10% more yield.

From my own experience, I still get great results with less then 800 PPFD, nice big sticky buds, just a bit fluffy. I am still up in the air about the fluffiness of the buds, in some ways it is nice and makes them burn in a more enjoyable way.

One of the things that the graphs don't show us is how coverage can really effect overall yield. For example if I do a big center solo light that gives us 800+ PPFD, I may hit saturation and it may not be productive to add more top center lighting. But if I add more light from the corners of the grow space angled in, I can get much more production with some extra light pushing PPFD well over a 1000, since the light is reaching deeper into the canopy to the lower leaves.

 

[captainmorgan]

One of the things that the graphs don't show us is how coverage can really effect overall yield. For example if I do a big center solo light that gives us 800+ PPFD, I may hit saturation and it may not be productive to add more top center lighting. But if I add more light from the corners of the grow space angled in, I can get much more production with some extra light pushing PPFD well over a 1000, since the light is reaching deeper into the canopy to the lower leaves.

I have my individual COB's evenly space over the screen.

 

[coolbreez1]

One of the things that the graphs don't show us is how coverage can really effect overall yield. For example if I do a big center solo light that gives us 800+ PPFD, I may hit saturation and it may not be productive to add more top center lighting. But if I add more light from the corners of the grow space angled in, I can get much more production with some extra light pushing PPFD well over a 1000, since the light is reaching deeper into the canopy to the lower leaves.

Yes, I think one of the advantages of the cobs is the ability to better spread out the light. I can spread out 9 cobs along the whole length of my 8x4 tent and have pretty even light coverage. With traditional lights you are going to be stuck with single point source of light, or maybe two lights in the space, but regardless you wont have as good of over all light coverage.