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Quote: LJB Originally Posted by The objective of this study was to determine the effect of light intensity, temperature and CO2 conditions on gas and water vapour exchange characteristics of C. sativa L. to establish suitable and efficient environmental conditions for its indoor cultivation.



Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions



Journal Physiology and Molecular Biology of Plants

Publisher Springer India

ISSN 0971-5894 (Print) 0974-0430 (Online)

Issue Volume 14, Number 4 / October, 2008

Category Research Article

DOI 10.1007/s12298-008-0027-x

Pages 299-306

Subject Collection Biomedical and Life Sciences

SpringerLink Date Thursday, February 26, 2009



Suman Chandra1 , Hemant Lata1, Ikhlas A. Khan1, 2 and Mahmoud A. Elsohly1, 3



(1) National Center for Natural Product Research, School of Pharmacy, University of Mississippi, Oxford, MS-38677, USA

(2) Department of Pharmacognosy, University of Mississippi, MS-38677 Oxford, USA

(3) Department of Pharmaceutics, School of Pharmacy, University of Mississippi, University, Oxford, MS 38677, USA



Published online: 26 February 2009



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 (PN) 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 (PN 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 (gs) also increased with PPFD irrespective of temperature. However, gs increased with temperature up to 30 °C only. Temperature above 30 °C had an adverse effect on gs in this species. Overall, high temperature and high PPFD showed an adverse effect on PN 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 gs 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 gs ∼ 29% and 42% respectively, and stimulated PN, 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.



Key words Cannabis sativa - Photosynthesis - Transpiration - Water use efficiency



https://www.springerlink.com/content/a3527u6018823x43/



full text pdf!!!!!: https://www.springerlink.com/content/...3/fulltext.pdf



******



Note that this study was conducted at the (public) University of Mississippi, but it appears this document was not published in the United States. Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditionsJournal Physiology and Molecular Biology of PlantsPublisher Springer IndiaISSN 0971-5894 (Print) 0974-0430 (Online)Issue Volume 14, Number 4 / October, 2008Category Research ArticleDOI 10.1007/s12298-008-0027-xPages 299-306Subject Collection Biomedical and Life SciencesSpringerLink Date Thursday, February 26, 2009Suman Chandra1 , Hemant Lata1, Ikhlas A. Khan1, 2 and Mahmoud A. Elsohly1, 3(1) National Center for Natural Product Research, School of Pharmacy, University of Mississippi, Oxford, MS-38677, USA(2) Department of Pharmacognosy, University of Mississippi, MS-38677 Oxford, USA(3) Department of Pharmaceutics, School of Pharmacy, University of Mississippi, University, Oxford, MS 38677, USAPublished online: 26 February 2009Abstract 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 (PN) 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 (PN 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 (gs) also increased with PPFD irrespective of temperature. However, gs increased with temperature up to 30 °C only. Temperature above 30 °C had an adverse effect on gs in this species. Overall, high temperature and high PPFD showed an adverse effect on PN 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 gs 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 gs ∼ 29% and 42% respectively, and stimulated PN, 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.Key words Cannabis sativa - Photosynthesis - Transpiration - Water use efficiency******Note that this study was conducted at the (public) University of Mississippi, but it appears this document was not published in the United States.

if really interested in their research, do actual request for specifics. they have to respond, as they are actually under f.d pieces of gold, under n.i.d.abuse, who have more volumes of research, dating back @ least a century. they too must provide free data, if requested.

dept of ag has volumes upon voulumes of records on history of h.mp/c.s.

actually used to be policies that farmers were encouraged to grow x amount of h.mp; to support naval/merchant marine industries during early indust. rev.



nice finds ljb...



https://www.nida.nih.gov/pdf/monographs/download79.html

excellent detailed science.



Quote: Originally Posted by jammie wow- love reading tech articles while i'm stoned. can anyone tell me which bulbs produce photosynthetic photon flux densities of ∼1500 μmol m−2s−1?? may have to contact the authors



the sun is ~450 par watts of full spectrum light.



required ~20 photons to make/store 1 molecule of sugar.



get the 1k's 2"-6" away and will get close to achiving leaf saturation, or ~300 par watts. in general, get lights as close as possible to plants, as long as air circulation is optimal, they can handle being very close to lamp. if cannot get/mimic full spectrum of sun, saturate plant w/ light by close proximity. the individual that has run that instituion for years is dr. elsohly. has many patents, and is intl. recognized relevant to c.s. lots of data on that persons work on net/in print.if really interested in their research, do actual request for specifics. they have to respond, as they are actually under f.d pieces of gold, under n.i.d.abuse, who have more volumes of research, dating back @ least a century. they too must provide free data, if requested.dept of ag has volumes upon voulumes of records on history of h.mp/c.s.actually used to be policies that farmers were encouraged to grow x amount of h.mp; to support naval/merchant marine industries during early indust. rev.nice finds ljb...excellent detailed science.a 1k mh, or hps, ~1 foot away from the plant will provide ~5,000 lumens, which is ~50,000 lux, which will be ~150-250 par watts; due to spectral deficiencies.the sun is ~450 par watts of full spectrum light.required ~20 photons to make/store 1 molecule of sugar.get the 1k's 2"-6" away and will get close to achiving leaf saturation, or ~300 par watts. in general, get lights as close as possible to plants, as long as air circulation is optimal, they can handle being very close to lamp. if cannot get/mimic full spectrum of sun, saturate plant w/ light by close proximity.