Great peer reviewed paper on optimal environment: temperature, CO2 and light intensity in cannabis sativa

[garyfisher]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550641/

Click for full text and pdf.

 

Abstract

Effect of different photosynthetic photon flux densities (0, 500, 1000, 1500 and 2000 μmol m⁻²s⁻¹), temperatures (20, 25, 30, 35 and 40 °C) and CO₂ concentrations (250, 350, 450, 550, 650 and 750 μmol mol⁻¹) on gas and water vapour exchange characteristics of Cannabis sativa L. were studied to determine the suitable and efficient environmental conditions for its indoor mass cultivation for pharmaceutical uses. The rate of photosynthesis (P_N) and water use efficiency (WUE) of Cannabis sativa increased with photosynthetic photon flux densities (PPFD) at the lower temperatures (20–25 °C). At 30 °C, PN and WUE increased only up to 1500 μmol m⁻²s⁻¹ PPFD and decreased at higher light levels. The maximum rate of photosynthesis (P_{N max}) was observed at 30 °C and under 1500 μmol m⁻²s⁻¹ PPFD. The rate of transpiration (E) responded positively to increased PPFD and temperature up to the highest levels tested (2000 μmol m⁻²s⁻¹ and 40 °C). Similar to E, leaf stomatal conductance (g_s) also increased with PPFD irrespective of temperature. However, g_s increased with temperature up to 30 °C only. Temperature above 30 °C had an adverse effect on g_s in this species. Overall, high temperature and high PPFD showed an adverse effect on P_N and WUE. A continuous decrease in intercellular CO₂ concentration (Ci) and therefore, in the ratio of intercellular CO₂ to ambient CO₂ concentration (Ci/Ca) was observed with the increase in temperature and PPFD. However, the decrease was less pronounced at light intensities above 1500 μmol m⁻²s⁻¹. In view of these results, temperature and light optima for photosynthesis was concluded to be at 25–30 °C and ∼1500 μmol m⁻²s⁻¹ respectively. Furthermore, plants were also exposed to different concentrations of CO₂ (250, 350, 450, 550, 650 and 750 μmol mol⁻¹) under optimum PPFD and temperature conditions to assess their photosynthetic response. Rate of photosynthesis, WUE and Ci decreased by 50 %, 53 % and 10 % respectively, and Ci/Ca, E and g_s increased by 25 %, 7 % and 3 % respectively when measurements were made at 250 μmol mol-1 as compared to ambient CO₂ (350 μmol mol⁻¹) level. Elevated CO₂ concentration (750 μmol mol⁻¹) suppressed E and g_s ∼ 29% and 42% respectively, and stimulated P_N, WUE and Ci by 50 %, 111 % and 115 % respectively as compared to ambient CO₂ concentration. The study reveals that this species can be efficiently cultivated in the range of 25 to 30 °C and ∼1500 μmol m⁻²s⁻¹ PPFD. Furthermore, higher PN, WUE and nearly constant Ci/Ca ratio under elevated CO₂ concentrations in C. sativa, reflects its potential for better survival, growth and productivity in drier and CO₂ rich environment.

[zeebudz]

Good stuff. But only saw the abstract. 

Since "This research was supported by National Institute of Drug Abuse (NIDA), USA, Contract # NO1DA-0-7707" and "The National Institute on Drug Abuse is a United States federal-government research institute whose mission is to lead the Nation in bringing the power of science to bear on drug abuse and addiction." I don't think the research paper police will mind upstanding, tax-paying citizens who helped fund this research to view the whole paper. So here ya' go:

http://sci-hub.tw/https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550641/

 

(EDIT: Oops, afterwards I saw the full text link in that original link from garyfisher. But if anyone doesn't know about sci-hub, please check it out.)

 

Edited February 10, 2019 by zeebudz

[Restorium2]

On ‎2‎/‎10‎/‎2019 at 12:27 AM, garyfisher said:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550641/

Click for full text and pdf.

 

Abstract

Effect of different photosynthetic photon flux densities (0, 500, 1000, 1500 and 2000 μmol m⁻²s⁻¹), temperatures (20, 25, 30, 35 and 40 °C) and CO₂ concentrations (250, 350, 450, 550, 650 and 750 μmol mol⁻¹) on gas and water vapour exchange characteristics of Cannabis sativa L. were studied to determine the suitable and efficient environmental conditions for its indoor mass cultivation for pharmaceutical uses. The rate of photosynthesis (P_N) and water use efficiency (WUE) of Cannabis sativa increased with photosynthetic photon flux densities (PPFD) at the lower temperatures (20–25 °C). At 30 °C, PN and WUE increased only up to 1500 μmol m⁻²s⁻¹ PPFD and decreased at higher light levels. The maximum rate of photosynthesis (P_{N max}) was observed at 30 °C and under 1500 μmol m⁻²s⁻¹ PPFD. The rate of transpiration (E) responded positively to increased PPFD and temperature up to the highest levels tested (2000 μmol m⁻²s⁻¹ and 40 °C). Similar to E, leaf stomatal conductance (g_s) also increased with PPFD irrespective of temperature. However, g_s increased with temperature up to 30 °C only. Temperature above 30 °C had an adverse effect on g_s in this species. Overall, high temperature and high PPFD showed an adverse effect on P_N and WUE. A continuous decrease in intercellular CO₂ concentration (Ci) and therefore, in the ratio of intercellular CO₂ to ambient CO₂ concentration (Ci/Ca) was observed with the increase in temperature and PPFD. However, the decrease was less pronounced at light intensities above 1500 μmol m⁻²s⁻¹. In view of these results, temperature and light optima for photosynthesis was concluded to be at 25–30 °C and ∼1500 μmol m⁻²s⁻¹ respectively. Furthermore, plants were also exposed to different concentrations of CO₂ (250, 350, 450, 550, 650 and 750 μmol mol⁻¹) under optimum PPFD and temperature conditions to assess their photosynthetic response. Rate of photosynthesis, WUE and Ci decreased by 50 %, 53 % and 10 % respectively, and Ci/Ca, E and g_s increased by 25 %, 7 % and 3 % respectively when measurements were made at 250 μmol mol-1 as compared to ambient CO₂ (350 μmol mol⁻¹) level. Elevated CO₂ concentration (750 μmol mol⁻¹) suppressed E and g_s ∼ 29% and 42% respectively, and stimulated P_N, WUE and Ci by 50 %, 111 % and 115 % respectively as compared to ambient CO₂ concentration. The study reveals that this species can be efficiently cultivated in the range of 25 to 30 °C and ∼1500 μmol m⁻²s⁻¹ PPFD. Furthermore, higher PN, WUE and nearly constant Ci/Ca ratio under elevated CO₂ concentrations in C. sativa, reflects its potential for better survival, growth and productivity in drier and CO₂ rich environment.

Growing cannabis is an art more than a science. All the variables change when you go from strain to strain. One formula across the board doesn't work anywhere but on paper. Sorry warehouse grower, it's just not that easy. It's not corn so we want more than one strain the rest of our lives. 

[Restorium2]

I watched a documentary about a regular farmer turned warehouse grower. He grew one strain, Blue Dream. That's it, one strain. He could grow that one strain well. Didn't realize it was a fail because he grew only one strain. This isn't corn. You can't summon Monsanto to your rescue. I bet that strain was weak and made huge buds because it's a BigBud cross. Try growing the old original grail strains like Headband, Chem D and OG Kush in your warehouse and see how you do. 

Edited February 11, 2019 by Restorium2

[zeebudz]

2 hours ago, Restorium2 said:

...

You can't summon Monsanto to your rescue.

...

Just wait; they're probably chomping at the bit to get into the cannabis space.

[Restorium2]

6 minutes ago, zeebudz said:

Just wait; they're probably chomping at the bit to get into the cannabis space.

They already are. Their strain never gets mites. Grows 5 pounds a plant. Beautiful huge sticky buds that nobody gets high off of. No one knows for sure it's really cannabis but it sure can make a really nice looking bag.

[Restorium2]

“Currently, Federal law criminalizes marijuana and hemp derivatives because public opinion is still against it and legal commercial production in the U.S. is currently handled by a patchwork of small farmers whom are not trusted by investors. A major player as Monsanto could bring confidence within government and towards investors in the market if it were to own a large part of the exploitable lands and commercial products”. 

Other experts, such as James Adamson, president of Medical Marijuana Technologies, believe the only way marijuana is to become legal in the US is through the branding of a GM strain

“There is presently no way to control the production of marijuana and the quality of the strains. A GM strain produced by a company with the credentials and prestige of Monsanto would definitely lend a massive hand to pro-legalization activists within certain spheres of government and within the business world” he explains.

[semicaregiver]

Could Monsanto become involved in cannabis?   hmm, their exclusive marketing and distribution partner for Roundup is Scotts Miracle Grow.   Scotts Miracle Grow is Sunlight Supply,  Agrolux, Botanicare, Gavita and General Hydroponics.   Yeah, probably a longshot that Monsanto would be involved in the cannabis space.