effexxess said:

Medical Cannabis recommended N, P, K levels from Volcani Center research:
N veg: Response of Medical Cannabis to Nitrogen Supply Under Long Photoperiod (2020)
P veg: Response of medical cannabis genotypes to P supply under long photoperiod: Functional phenotyping and the ionome (2021)
K veg: Response of Medical Cannabis Genotypes to K Supply Under Long Photoperiod (2019)
N flower: Nitrogen supply affects cannabinoid and terpenoid profile in medical cannabis ( Flowering phase 2021)
P flower: The Highs and Lows of P Supply in Medical Cannabis: Effects on Cannabinoids, the Ionome, and Morpho-Physiology (2021)
K flower: Effect of Potassium (K) Supply on Cannabinoids, Terpenoids and Plant Function in Medical Cannabis (2022)

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Can you tldr it for us?

So this is from the first paper:

We report that the morpho-physiological function under long photoperiod in medical cannabis is optimal at 160 mgL−1 N supply, and significantly lower under 30 mgL−1 N, with visual deficiency symptoms, and 75 and 25% reduction in plant biomass and photosynthesis rate, respectively.



That's interesting info, although I have not read the whole study(s)

160 mg/L = 160PPM, right?

effexxess said:

Medical Cannabis recommended N, P, K levels from Volcani Center research:
N veg: Response of Medical Cannabis to Nitrogen Supply Under Long Photoperiod (2020)
P veg: Response of medical cannabis genotypes to P supply under long photoperiod: Functional phenotyping and the ionome (2021)
K veg: Response of Medical Cannabis Genotypes to K Supply Under Long Photoperiod (2019)
N flower: Nitrogen supply affects cannabinoid and terpenoid profile in medical cannabis ( Flowering phase 2021)
P flower: The Highs and Lows of P Supply in Medical Cannabis: Effects on Cannabinoids, the Ionome, and Morpho-Physiology (2021)
K flower: Effect of Potassium (K) Supply on Cannabinoids, Terpenoids and Plant Function in Medical Cannabis (2022)

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Just started looking. Sounds like bloom nutes and flushing are a good thing again.

Thanks for sharing. Going to read this later.

Moe.Red said:

So this is from the first paper:

We report that the morpho-physiological function under long photoperiod in medical cannabis is optimal at 160 mgL−1 N supply, and significantly lower under 30 mgL−1 N, with visual deficiency symptoms, and 75 and 25% reduction in plant biomass and photosynthesis rate, respectively.

View attachment 1282294

That's interesting info, although I have not read the whole study(s)

160 mg/L = 160PPM, right?

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I checked and you’re right, 1 mg/L = 1 ppm

BehindEnemyLines said:

I checked and you’re right, 1 mg/L = 1 ppm

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Not sure what the -1 means after the L in the paper. It’s a -1 exponent. Never seen it expressed that way.

Moe.Red said:

Not sure what the -1 means after the L in the paper. It’s a -1 exponent. Never seen it expressed that way.

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A negative exponent shows that a base is on the denominator side of the fraction line. In other words, the negative exponent rule tells us that a number with a negative exponent should be put to the denominator, and vice versa. For example, when you see x^-3, it actually stands for 1/x^3.

120-130ppm is where i find my nitrogen to be right for my conditions and the ratios i generally run.

lots of things effect nitrogen availability so the number thats ideal will also vary. Eg. Nutrient ratios, ph, transpiration rates, light intensity etc etc etc. id say it could range from 100-200 ppm which is quite a swing. The major influence is the nutrient ratios.

Good info and ill add this one to it to give a visual idea of what im talking about.

"The plants were grown under five N treatments of 30, 80, 160, 240, and 320 mg L−1 (ppm) under environmentally controlled conditions. The results revealed that N supply affects cannabinoid and terpenoid metabolism, supporting the hypothesis. The concentrations of most cannabinoids and terpenoids tested were highest under the deficient concentration of 30 mg L−1 N and declined with the elevation of N supply."

growsince79 said:

"The plants were grown under five N treatments of 30, 80, 160, 240, and 320 mg L−1 (ppm) under environmentally controlled conditions. The results revealed that N supply affects cannabinoid and terpenoid metabolism, supporting the hypothesis. The concentrations of most cannabinoids and terpenoids tested were highest under the deficient concentration of 30 mg L−1 N and declined with the elevation of N supply."

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Dont take this as fact… its only my best guess that the low N leads to smaller buds and more concentrated cannabinoids. I have never posted this thought before but i do (as off the wall as it sounds) feel like the environmental stress of crop steering, UV etc. excluding PGRs that show an increase in cannabinoids is due to the tighter more compact and smaller buds as a result we see this increase.

like i said until now i kinda kept this to myself as i have 0 evidence of such but i just cant seem to shake that gut feeling

Aqua Man said:

Dont take this as fact… its only my best guess that the low N leads to smaller buds and more concentrated cannabinoids. I have never posted this thought before but i do (as off the wall as it sounds) feel like the environmental stress of crop steering, UV etc. excluding PGRs that show an increase in cannabinoids is due to the tighter more compact and smaller buds as a result we see this increase.

like i said until now i kinda kept this to myself as i have 0 evidence of such but i just cant seem to shake that gut feeling

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HAHA i never take anything as fact man. More N should absolutely make bigger buds. Just saying, the articles seem to support bloom nutes and flushing. I haven't read it all yet.

growsince79 said:

HAHA i never take anything as fact man. More N should absolutely make bigger buds. Just saying, the articles seem to support bloom nutes and flushing. I haven't read it all yet.

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lol i know ya don’t… thats why i pay close attention to information and the observations you post. its one of the best sources of anecdotal evidence on the site because its just as you see it. Honestly you and Mimed who hasent been around in some time are the 2 best sources of observation i see. Not that there is not a shot load of others also but you too really just call it the way you see it and it sticks out to me is all

Aqua Man said:

lol i know ya don’t… thats why i pay close attention to information and the observations you post. its one of the best sources of anecdotal evidence on the site because its just as you see it. Honestly you and Mimed who hasent been around in some time are the 2 best sources of observation i see. Not that there is not a shot load of others also but you too really just call it the way you see it and it sticks out to me is all

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I'm just too old to care who agrees or not. haha

Moe.Red said:

Can you tldr it for us?

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Nitrogen, Veg Cycle.
Response of Medical Cannabis to Nitrogen Supply Under Long Photoperiod (2020)
Avia Saloner and Nirit Bernstein

“The plants were then divided into five treatments of N supply: 30, 80, 160, 240, and 320 ppm N,
five plants per treatment, and grown for an additional 32 days under 18/6 h light/dark photoperiod. Light
was supplied by Metal Halide bulbs (400 μmol m2 s1; Solis Tek Inc, Carson, California).

“N was supplied in the concentrations of 2.1, 5.7, 11.4, 17.1, and 22.9 mM (millimolar) [e.g., 30,
80, 160, 240, and 320 mgL-1 (ppm), respectively], 80% in the form of N-NO3- and 20% as N-NH4+.

“We report that the morpho-physiological function under long photoperiod in medical cannabis is
optimal at 160 mg L N supply. The plants demonstrated sensitivity to
high N supply, and supply above 160 mg L, was found to be
excessive, restricting growth and biomass deposition. Optimal plant
growth and development were obtained under 160 mg L N supply.”

Vegetative Growth
N - 160 mg L


Phosphorous, Veg Cycle.
Response of medical cannabis genotypes to P supply under long photoperiod:
Functional phenotyping and the ionome (2021)
Sivan Shiponi and Nirit Bernstein

“The plants were grown 30 days under increasing P
treatments of 5, 15, 30, 60, 90 mg L-1 in controlled growing
rooms under long photoperiod (18/6 h light/dark), 25 ◦C,
and irradiated with Metal halide bulbs (400 μmol m2 s1;
Solis Tek Inc, Carson, California; 25.9 mol m2 d1). Carbon
dioxide concentration was ~400 ppm.

“Our results suggest a wide optimum range for P in
medicinal cannabis at the vegetative growth stage, with a
minimum requirement of 15 mg L P and a recommended
application of 30 mg L. Biomass accumulation into leaves,
stems and roots increased with the elevation of P supply up
to the concentration of 30 mg L P and was unaffected by
further increase.”

Vegetative growth
P - 30 mg L



Potassium, Veg Cycle.
Response of Medical Cannabis
Genotypes to K Supply Under Long Photoperiod (2019)
Avia Saloner, Mollie M. Sacks and Nirit Bernstein

“The plants were exposed to five levels of K (15, 60, 100, 175, and 240 ppm K). The plants were
then divided into five increasing treatments of K supply; 15, 60, 100, 175, and 240 ppm, and grown
for 30 days under 18/6 h light/dark photoperiod using Metal Halide bulbs (400 μmol m2 s1, Solis Tek Inc, Carson, California).

“Growth response to K inputs varied between genotypes, revealing genetic differences
within the Cannabis sativa species to mineral nutrition. The concentration of the two major cation
nutrients, Ca and Mg, tended to decrease with increased K supply, demonstrating competition for uptake.

“15 ppm of K was insufficient for optimal growth and function in both genotypes and elicited
visual deficiency symptoms. Biomass of leaves, stems, and roots increasing with the increase in K
concentration, up to 175 ppm K, and decreasing with further increase in concentration, hence presenting
15 ppm as a sub-optimal concentration and 175 ppm as an optimal K
concentration. 240 ppm K proved excessive and damaging to
development of the genotype Royal Medic, while in Desert Queen it
stimulated rather than restricted shoot and root development.”

Vegetative Growth
K – 175 (up to 240 ppm)



Nitrogen, Flowering Cycle.
Nitrogen supply affects cannabinoid and terpenoid profile in medical cannabis (2021)
Avia Saloner and Nirit Bernstein

“We studied the impact of N application on chemical
and functional-physiology phenotyping in medical cannabis
at the flowering stage. The plants were grown under five N
treatments of 30, 80, 160, 240, and 320 mg L (ppm), for 56
days, and light was supplied by HPS bulbs (980 μmol m2 s1).

“These results suggest that high N supply has
adverse effects on the production of secondary compounds in
cannabis, while it promotes growth and biomass production.
Our results demonstrate that N supply up to 160 mg L,
dramatically increased inflorescence biomass, while higher
application levels did not induce an additional significant
effect. Taken together with the negative impacts obtained for
high N supply on secondary metabolite accumulation, we
suggest that the optimal level for excelled yield quantity, as
well as quality, i.e., high secondary metabolites profile, is
160 mg L N.”

Flowering growth
N - 160 mg L


Phosphorous, Flowering growth.
The Highs and Lows of P Supply in Medical Cannabis: Effects on Cannabinoids, the Ionome, and Morpho-Physiology (2021)
Sivan Shiponi and Nirit Bernstein

“The plants in each group received one of five P concentrations (5,
15, 30, 60, and 90 mg L P), and short photoperiod was applied (12/12-h
light/dark) using high-pressure sodium bulbs (980 mmol m2 s1) for 63
and 68 days for Desert Queen and Royal Medic, respectively. This
concentration range was chosen with the goal to target deficiency as
well as over-supply of P.

“Cannabinoid concentrations decreased linearly with increasing yield, consistent with a yield
dilution effect, but the total cannabinoid content per plant increased with increasing P supply. These results
reveal contrasting trends for effects of P supply on cannabinoid concentrations that were highest under <30
mg L P, vs. inflorescence biomass that was highest under 30–90 mg L P.

“Cannabinoid concentrations in the inflorescence were affected by the P treatments and overall
reduced with the increase in P supply. THCA and CBDA concentrations had the most profound response to
P concentrations and were reduced with P supplement in both genotypes and at both locations in the plant
(i.e., in the primary and secondary inflorescences). The foremost discovery is the contrasting effect of
increasing P supply to increase inflorescence yield production but to decrease the biosynthesis.”

Flowering growth
P - 60 mg L average (30-90 mg L)



Potassium, Flowering growth.
Effect of Potassium (K) Supply on Cannabinoids, Terpenoids and Plant Function in Medical Cannabis (2022)
Avia Saloner and Nirit Bernstein

Abstract
We have demonstrated in previous studies that the essential macro-nutrients nitrogen (N) and
phosporous (P) have profound effects on the production of cannabinoids and terpenoids in the
cannabis plant. The present study was undertaken to evaluate the hypothesis that potassium (K)
supply, which is known to substantially affect plant development and function, affects the
secondary metabolism of the cannabis plant. Two cultivars of medical cannabis were grown in
controlled environment conditions, under five levels of K supply: 15, 60, 100, 175, and 240 mg L−1 K.
The results revealed that the development and function of plants that received the low K supply of
15 mg L−1 K were impaired, as the plants suffered from visual chlorosis, and the inflorescence
yield was reduced in both cultivars. Plants that received higher K inputs in the range of −175 mg
L−1 K demonstrated optimal plant function and high yield, and one cultivar demonstrated oversupply
symptoms under the high K level of 240 mg L−1. The concentrations of most cannabinoids
and terpenoids declined with the elevation of K supply, thus supporting the hypothesis. As
secondary metabolite concentrations decreased with the increase in K supply, and higher K levels
had no positive effects, 60 mg L−1 K is the suggested application level to maintain high function
and yield combined with high secondary metabolism.

Flowering growth
P - 60 mg L average (30-90 mg L)

BigBlonde said:

A negative exponent shows that a base is on the denominator side of the fraction line. In other words, the negative exponent rule tells us that a number with a negative exponent should be put to the denominator, and vice versa. For example, when you see x^-3, it actually stands for 1/x^3.

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Why no just write it ml/L then? So 160 mgL-1 is 160 mg/L, right? Is this a European thing or something like that?

Asuming that these scientist were right with their findings, is the use of PK Boosters in flower superflous? (Or has it always been even before that study?)

hydrodreams said:

Asuming that these scientist were right with their findings, is the use of PK Boosters in flower superflous? (Or has it always been even before that study?)

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That really depends on what you are putting in already.

Moe.Red said:

That really depends on what you are putting in already.

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Asuming I would use the amounts they conclude in the study (for flower): N160-P60-K60..... PK Boosters would add a serious quantity to those amounts of P and K in the study and therefore contradict their study.