The myth, of the high P myth?

[YosemiteSam]

Thanks. I will crank it down to 800 and see what I see.

It makes sense based on what i have seen though and it ain't the first time that prevailing wisdom may be wrong.

 

[spurr]

Thanks. I will crank it down to 800 and see what I see.

Great! Let us know what you think, if you don't mind would you post the outcome in the Co2 thread I referred to? Thanks.

It makes sense based on what i have seen though and it ain't the first time that prevailing wisdom may be wrong.

Do you mean Co2 < 1,500 ppm "makes sense", or that Co2 of 1,500 ppm "makes sense"? And I agree that "... it ain't the first time that prevailing wisdom may be wrong."; as exemplified by this high P thread

Sadly, I have found so many incorrect claims from "prevailing wisdom" in the cannabis world it makes my head spin. I blame Mel Frank, Jorge Cervantes (sp?), et al., for staring and continuing the incorrect claims.

I have been on a mission to correct all the wrong info in the cannabis world for the past couple of years. And often I feel like I'm just spinning my wheels because there is SO much wrong info, and SO many people parroting said wrong info to other people, at no fault of their own because they don't know better. Generally, the very last place I look for sound and accurate info on cannabis (re plant physiology and photobiology, etc.) is the cannabis world.

 

[YosemiteSam]

My highest yield ever (gram per watt) came in a grow that was not CO2 enhanced. Let's just say it is on a very busy street and gets quite a bit of CO2...closer to what you are talking about.

That is why your claim that lower may be better makes sense to me.

 

[spurr]

Good to hear. Everyone I have discussed this issue with, whom has used ~600-1,000 ppm Co2, found better (if not merely the same) results vs 1,500 ppm. And one saves money on Co2 tanks or propane (for Co2 burners) too

 

[DonkDBZ]

Good to hear. Everyone I have discussed this issue with, whom has used ~600-1,000 ppm Co2, found better (if not merely the same) results vs 1,500 ppm. And one saves money on Co2 tanks or propane (for Co2 burners) too

What were the canopy temps of the growers?

Co2 ppm needed is relative to heat and humidity.

Which comes down to strain. A skywalker cut I had could take 84+ temps and not even be bothered. while the jack the ripper looked like shit.

 

[spurr]

You'll find 1500ppm is the ag standard for tomatoes and other greenhouse crops. As they are a C3 its a pretty good guage. In fact 1500 has been set as the standard because while you may get higher yields running at say 1800 the cost of CO2 likely outweighs the commercial benefits. Sorry Spurr have to disagree again.

Mullray, that's just flat wrong; everything I wrote is correct. I have lots of references to back up what I wrote ... but this isn't the thread for this debate. You can post in the Co2 thread in the science forum if you wish.

 

[spurr]

Why would lower be better?

Did you not read what I wrote re Rubisco activase, Co2 saturation, stomatal conductance, etc.?

When cannabis and other C3 higher plants were evolving into what they are today, the Co2 levels were ~700-1,000 ppm. That, IMO, is why today the Co2 saturation point is ~1,000 ppm.

The factory of photosynthesis (the chloroplasts) can only use so much CO2 absolutely and at some point critical mass is achieved. But at which point the additional CO2 goes to waste.

The word you are looking for is not "critical mass" but "saturation" (as in "saturation point"); and Co2 saturation happens ~1,000 ppm* for most higher C3 plants, this has been proven many time for many years.

And it's more than "Co2 goes to waste", too much Co2 will actually hinder Pn due to hindering Rubisco activase.

* just like light saturation happens at > ~1,600 umol/area^2/second for cannabis (i.e., instantaneous photons within PAR range)

Spurr how is it that a grower with anedotal feedback you take as everyone agreeing?

Huh? What are you referring to? What I wrote is based upon sound, proven science, including studies on cannabis. I and others have tested said info and found it to be correct; granted I haven't used a Chl fluorometer or Pn chmaber, yet ...

I guess this is where you and I clash on a few subjects. I for one disagree and actually found about 1750ppm was critical mass using equipment that monitored photon to sugar conversion rates (i.e. a fairly accurate measurement of photosynthesis).

Sorry I but do not believe you, I'm not trying to be rude, but what you wrote does not ring with truth. High quality/high accurate Pn measurement tools are well into the $30-50K range; granted, for ex., Qubit Systems does sell tools to measure Pn at lower cost than say Li-cor. The cheapest and and sufficiently accurate method would probably be using a Chl fluorometer like the EARS "PPM-300" or Walz "PAM 2500".

Pray tell: what is the name of the analytical tools you used? You could post back to me in the Co2 thread, and please be aware I know all about how to measure Pn, Co2 fixation, Gs, E, etc., etc. Ex., it's not accepted as highly accurate, nor sound, to try and find Pn of higher plants by "monitor[ing] photon to sugar conversion rates". Next are you going to write you used the leaf-in-water method to count bubbles as a means to quantify Pn?

The fact is, what you claim to have done, and found, goes against all published studies and accepted science, of which I am aware; incl. studies on cannabis.

 

[spurr]

What were the canopy temps of the growers?

Co2 ppm needed is relative to heat and humidity.

Which comes down to strain. A skywalker cut I had could take 84+ temps and not even be bothered. while the jack the ripper looked like shit.

You do not want to bring heat above ~84-86'F; that is peak for peak rate of photosynthesis for cannabis, when Co2 is also at peak as well as irradiance. This has been studied and written about in published papers on cannabis. Once temps are > ~90'F Rubisco activase is hindered, just like when Co2 is > ~1,200.

The two factors that affect Rubisco activase are high temp and high Co2. Most people are unaware of Rubisco activase, but it's a critical point to understand for the best and most efficient growth.

 

[Guest 18340]

 

[spurr]

This notion that mj plants can handle much higher temps with CO2 is flawed.

Sort of. It's proven via at least two published studies I know of; when Co2 is increased temp should also be increased to increase Pn (rate of photosynthesis) as much as possible.

No Co2 = good temp is ~78-80'F
With Co2 = good temp is ~82-86 'F.

certainly to some degree the plant becomes more tolerant to higher temps - however optimum growth under CO2 enrichment or without CO2 enrichment will still be achieved within an optimum temp range of about 77 F - 82.4 F (25 - 28 C).

Again, that's just flat wrong and has been proven such in published papers on cannabis looking at effects of irradiance, temp and Co2 upon rate of photosynthesis.

The problem I expect is people approach a very complex system of control (air cooled of water cooled lamps, air con + dehumidifiers) without the right equipment and try and cheat it and go wow my overheated room still grows weed. I think what these guys are finding is some strains are more tolerant to heat than others.

Everything I wrote is correct, I do not make claims based on hearsay, conjecture or assumption; all my claims are backed up by sound science ...

Okay, lets take this Co2 talk out of this thread and into a Co2 thread; where it belongs. This thread is about P, not Co2. There is a Co2 thread in the science sub-forum where you could post your opinion and you may get more debate/responses than in a thread about P.

 

[spurr]

Co2 ppm needed is relative to heat and humidity.

Efficacy of increased Co2 (in terms of Pn) is most dependent upon temp and irradiance. When both are ideal (being the numbers I posted in that last few posts), Co2 provides most benefit in terms of Pn.

 

[spurr]

I thought you said this wasn't the forum for debate but then go onto debate.

I was merely responding to the posts already made on the topic of Co2, in this thread (so as not to be rude and ignore people). But I will defer to my suggestion that this topic should be brought to the Co2 thread and I will not be discussing Co2 any long in this thread.

Next are you going to write you used the leaf-in-water method to count bubbles as a means to quantify Pn?

Can't say as I've even heard of the method but nice sarcasm anyway

It was the first method used to see/quantify Pn from a plant many decades ago. I was only making slight joke, not trying to rile you up or anything

 

[spurr]

Mullray,

I edited my post above after you read it, I think, below is what I added. And in all my posts to you on Co2 I was not trying to be a jerk to you. I think I sometimes I come across that way, and if so I am sorry. Please trust me when I write that was not my intention.

Next are you going to write you used the leaf-in-water method to count bubbles as a means to quantify Pn?

Can't say as I've even heard of the method but nice sarcasm anyway

It was the first method used to see/quantify Pn from a plant many decades ago. I was only making slight joke, not trying to rile you up or anything

 

[YosemiteSam]

It is not going to be easy to convince me to try lower P past stretch again when I keep getting results like these


Chunky Cherry Malawi with about a week to go.

 

[Storm Shadow]

It is not going to be easy to convince me to try lower P past stretch again when I keep getting results like these
View attachment 119290

Chunky Cherry Malawi with about a week to go.

This was grown with Low P from start to finish...not to mention I didnt flush and my plants taste and smoke 10x better then b4

Spurr thanks for saving me a tons on nutes....and better yet..thanks for helping me pump out real dank!

 

[spurr]

Mullray,

I posted that study, if it's the same one I am thinking about, some time ago. But it's wasn't cops who grow it, it was scientists in NZ, and they claimed to have had lots of 'newbie errors' in growing. In the publicly available study I have, the scientists did not give any grow details (ex., irradiance, fertilizers, etc.); there was a 'part 2' to the study, which was not made public, that had the grow info. (the cops and scientists claimed they 'worried' about teaching people how to grow, so part 2 was not made public; lol, like people just can't come to ICmag to learn how to grow!)

Are we referring to the same study, or do you have access to part 2? Or are we not referring to the same study? If you have access to part 2 I would love to read it, thanks.

 

[tester]

The results of an experimental indoor hydroponic Cannabis growing study, using the ‘Screen of Green’ (ScrOG) method—Yield, tetrahydrocannabinol (THC) and DNA analysis. Forensic Science International 2010, 202:36-44.Knight G, Hansen S, Connor M, Poulsen H, McGovern C, Stacey J:

Here is the full doc originally uploaded by Spurr.

 

[DonkDBZ]

This was grown with Low P from start to finish...not to mention I didnt flush and my plants taste and smoke 10x better then b4

Spurr thanks for saving me a tons on nutes....and better yet..thanks for helping me pump out real dank!

was that with spurs 5/5/5/5 ? what was your rough gpw?

 

[tester]

Just to take this thread off the track once again:
Remember about that far fetched idea that Botrytis might be even usefull somehow?

"There appears to be a relationship between increased incidence of fungal Botrytis infection, and increased percentage of THC, the psychoactive agent, in the industrial hemp plant."
http://www.druglibrary.net/olsen/HEMP/IHA/jiha6210.html

 

[YosemiteSam]

I wonder if it is actually the incidence of mold or the conditions that led to the mold that may jack up thc?