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The Effect of Light Spectrum on the Morphology and Cannabinoid Content of Cannabis sativa L


Abstract and Figures

Cannabis sativa L. flowers are the main source of Δ-9-tetrahydrocannabinol (THC) used in medicine. One of the most important growth factors in cannabis cultivation is light; light quality, light intensity, and photoperiod play a big role in a successful growth protocol. The aim of the present study was to examine the effect of 3 different light sources on morphology and cannabinoid production. Cannabis clones were grown under 3 different light spectra, namely high-pressure sodium (HPS), AP673L (LED), and NS1 (LED). Light intensity was set to ∼450 µmol/m2/s measured from the canopy top. The photoperiod was 18L: 6D/21 days during the vegetative phase and 12L: 12D/46 days during the generative phase, respectively. At the end of the experiment, plant dry weight partition, plant height, and cannabinoid content (THC, cannabidiol [CBD], tetrahydrocannabivarin [THCV], cannabigerol [CBG]) were measured under different light treatments. The experiment was repeated twice. The 3 light treatments (HPS, NS1, AP673L) resulted in differences in cannabis plant morphology and in cannabinoid content, but not in total yield of cannabinoids. Plants under HPS treatment were taller and had more flower dry weight than those under treatments AP673L and NS1. Treatment NS1 had the highest CBG content. Treatments NS1 and AP673L had higher CBD and THC concentrations than the HPS treatment. Results were similar between experiments 1 and 2. Our results show that the plant morphology can be manipulated with the light spectrum. Furthermore, it is possible to affect the accumulation of different cannabinoids to increase the potential of medicinal grade cannabis. In conclusion, an optimized light spectrum improves the value and quality of cannabis. Current LED technology showed significant differences in growth habit and cannabinoid profile compared to the traditional HPS light source. Finally, no difference of flowering time was observed under different R:FR (i.e., the ratio between red and far-red light).
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Basic Science – Research Article
Med Cannabis Cannabinoids 2018;1:19–27
The Effect of Light Spectrum on the
Morphology and Cannabinoid Content of
Cannabis sativa L.
Gianmaria Magagnini
a Gianpaolo Grassi
a Stiina Kotiranta
a Council for Agricultural Research and Economics, Research Centre for Cereal and Industrial Crops (CREA-CI),
Rovigo, Italy; b Valoya Oy, Helsinki, Finland
Received: March 14, 2018
Accepted: March 26, 2018
Published online: June 12, 2018
Gianpaolo Grassi
Council for Agricultural Research and Economics
Research Centre for Cereal and Industrial Crops (CREA-CI)
IT–45100 Rovigo (Italy)
E-Mail gianpaolo.grassi @
© 2018 The Author(s)
Published by S. Karger AG, Basel
DOI: 10.1159/000489030
Cannabis sativa L. · LED · Light spectrum · Cannabinoid
Cannabis sativa L. flowers are the main source of Δ-9-
tetrahydrocannabinol (THC) used in medicine. One of the
most important growth factors in cannabis cultivation is
light; light quality, light intensity, and photoperiod play a big
role in a successful growth protocol. The aim of the present
study was to examine the effect of 3 different light sources
on morphology and cannabinoid production. Cannabis
clones were grown under 3 different light spectra, namely
high-pressure sodium (HPS), AP673L (LED), and NS1 (LED).
Light intensity was set to 450 µmol/m2/s measured from
the canopy top. The photoperiod was 18L: 6D/21 days during
the vegetative phase and 12L: 12D/46 days during the gen-
erative phase, respectively. At the end of the experiment,
plant dry weight partition, plant height, and cannabinoid
content (THC, cannabidiol [CBD], tetrahydrocannabivarin
[THCV], cannabigerol [CBG]) were measured under different
light treatments. The experiment was repeated twice. The 3
light treatments (HPS, NS1, AP673L) resulted in differences
in cannabis plant morphology and in cannabinoid content,
but not in total yield of cannabinoids. Plants under HPS treat-
ment were taller and had more flower dry weight than those
under treatments AP673L and NS1. Treatment NS1 had the
highest CBG content. Treatments NS1 and AP673L had high-
er CBD and THC concentrations than the HPS treatment. Re-
sults were similar between experiments 1 and 2. Our results
show that the plant morphology can be manipulated with
the light spectrum. Furthermore, it is possible to affect the
accumulation of different cannabinoids to increase the po-
tential of medicinal grade cannabis. In conclusion, an opti-
mized light spectrum improves the value and quality of can-
nabis. Current LED technology showed significant differenc-
es in growth habit and cannabinoid profile compared to the
traditional HPS light source. Finally, no difference of flower-
ing time was observed under different R:FR (i.e., the ratio be-
tween red and far-red light). © 2018 The Author(s)
Published by S. Karger AG, Basel
Cultivating Cannabis sativa L. (Cannabaceae) differs
from other horticultural plants by the end product that is
harvested. The total yield cannot be rated only by the
weight of the flowers; the chemical composition of the
This article is licensed under the Creative Commons Attribution-
NonCommercial-NoDerivatives 4.0 International License (CC BY-
NC-ND) (
Usage and distribution for commercial purposes as well as any dis-
tribution of modified material requires written permission.
Med Cannabis Cannabinoids 2018;1:19–27
DOI: 10.1159/000489030
end product is also in the interest of the producers and
end users. Different cannabis chemotypes contain nu-
merous chemical compounds, such as cannabinoids,
which are known to exert various pharmacological ef-
fects. Morphology and cannabinoid profile are depen-
dent on genetic and environmental factors. For a medici-
nal cannabis producer, a continuous and uniform yield
and production of a specific cannabinoid compound or a
ratio between the different cannabinoids throughout the
canopy and between growth cycles is important. There-
fore, more and more professional medicinal cannabis
producers are moving from greenhouses to indoors, into
controlled and closed growth chambers. In growth cham-
bers, it is possible to adjust temperature, humidity, light
intensity, light spectrum, and air CO2 concentration. One
of the most important growth factors in cannabis cultiva-
tion is light. Light quality, light intensity, and photope-
riod play a significant role in a successful growth proto-
col. Growing indoors also improves the pest management
and reduces the susceptibility of the crop to natural con-
ditions, such as bad weather. In addition to the environ-
mental factors, the regulatory authorities also increasing-
ly push licensed producers towards producing, packag-
ing, and labeling their products indoors at the producer’s
site. As said, indoor production offers the ability to culti-
vate year round under stable conditions resulting in up to
6 harvests per year. This makes indoor cropping 15–30
times more productive than outdoor cultivation [1]. Also,
the historically illegal nature of cannabis has pushed the
cultivation inside into artificial environments due to the
fear of being caught committing a crime [2]. In addition
to the positive effects of environmental control, indoor
production minimizes the risk of cross-pollination with
other nearby crops, particularly industrial hemp, to guar-
antee flowers without fertilization or seed maturation. On
the other hand, indoor cannabis cultivation is energy in-
tensive due to the high light demand and cooling of the
closed environment. Cannabis is a plant adapted to high
irradiance levels and warm temperatures. Chandra et al.
[3] demonstrated that the highest photosynthetic effi-
ciency was achieved under 1,500 PPFD (Photosynthet-
ic Photon Flux Density) and 25–30°C; however, there is
no evidence that a higher photosynthesis rate equals
higher flower yields. It is also questionable whether such
a high light intensity (1,500 PPFD) is economically fea-
sible in terms of energy costs put into lighting and cool-
ing. Indoor cannabis agriculture has in fact been classified
as one of the “most energy intensive industries in the
U.S.” [4]. Lighting alone consumes 79–86% of the total
electricity use [5, 6] in the cannabis farms. It has been cal-
culated that 1% of the total energy consumption in the
USA is for cannabis cultivation, and in top production
states, such as California, the equivalent value is 3% [6].
Often, cannabis production sites have separate facilities
or rooms for each growth phase due to the different pho-
toperiods and other environmental demands. There are
3 distinct phases in cannabis cultivation: propagation
phase, vegetative growth phase, and flowering phase. In
the interview study conducted by Sweet [7], it was noted
that 600–1,000 W high-pressure sodium (HPS) lights
were the most commonly used lighting source in Wash-
ington State during the flowering phase. In contrast, a
wide variety of lighting types were reported to be used in
the vegetative rooms, such as fluorescent light bulbs (CFL
or T5), metal halide bulbs (MH), HPS lamps, induction
bulbs, light-emitting diodes (LED), or a combination of
different lighting types. During the propagation phase,
the most commonly used lighting source is fluorescent
light [8]. When using older technology, such as HPS or
fluorescent light, the spectrum is seldom adjusted accord-
ing to the plants’ needs: the technology has been origi-
nally developed for totally different applications, such as
street or office lighting. In the horticulture and crop sci-
ence industry, it has been long known that one can ma-
nipulate plant morphology and metabolism with the light
spectrum. For example, blue light has been shown to de-
crease internode length and enhance compactness of
various species [9, 11], whereas far-red and green wave-
lengths have been shown to induce shade avoidance syn-
drome symptoms, including stem and leaf elongation
and premature flowering [12]. A recently published paper
from the Czech Republic also concluded that cannabis
plants grown under a red and blue light spectrum had
shorter internodes and a smaller leaf area compared to a
white light source [13]. However, the paper does not give
more specific information about the spectra used. In ad-
dition to morphological changes, light spectrum and ir-
radiance level also have an impact on plant metabolism.
The plant receives signals from the light environment
through photoreceptors. Phytochromes, cryptochromes,
phototropins, and UVR8 are the most well-studied pho-
toreceptor groups found in higher plants. Phytochromes
are the red- and far-red-sensing photoreceptors which
regulate, for example, flowering, shade avoidance syn-
drome behavior, and germination in many species. Cryp-
tochromes and phototropins are regulated mainly by blue
and green wavelengths [14, 15]. UVR8 is responsible for
UV-B-induced responses. Short wavelength irradiation
has been shown to enhance the plant defense mechanism
by inducing metabolic activity, such as phenolic com-
Light Spectrum and Cannabis sativa L.
Med Cannabis Cannabinoids 2018;1:19–27
DOI: 10.1159/000489030
pound synthesis. Phenolic compounds, including antho-
cyanins, found especially in red-colored leaves, have been
shown to accumulate in lettuce leaves under short-wave-
length blue and UV light. Many phenolic compounds are
part of the plants’ defense mechanism, which are synthe-
sized under environmental stress. Short-wavelength ir-
radiation and high photon flux irradiance are examples
of light-related environmental stress. Several cannabi-
noids have also been suggested to be involved in the plant
defense mechanism and to have antioxidant properties,
including Δ-9-tetrahydrocannabinol (THC) and canna-
bidiol (CBD) [16] as well as cannabigerol (CBG) [17].
Bouquet [18] hypothesized that cannabis resin has a pro-
tective sunscreen function. However, the glands and the
secreted resin are accumulated on the lower leaf surface
instead of the upper surface and in the perigonial bracts
in the inflorescence which should be more susceptible to
sun light [19]. While light quality may have an effect on
the cannabinoid synthesis, cannabis yields are thought to
strongly correlate with increasing light intensity [3, 20].
However, light intensity did not seem to affect the can-
nabinoid concentration when plants were grown under
different light intensities under HPS light [21, 22]. In the
studies by Vanhove et al. [22] and Potter and Duncombe
[21], it was concluded that THC concentrations of flower
material could be primarily linked to cannabis variety in-
stead of cultivation method. In both studies, an increasing
irradiance level correlated positively with flower dry
weight, which resulted in higher total cannabinoid yield
in the high irradiance treatments. However, the effects of
different light qualities, or spectral composition, on can-
nabinoid synthesis and concentration in floral parts re-
main elusive. There are no recent light-related studies
conducted with cannabis and based on cannabinoid pro-
files. However, already in very early studies in 1983,
Mahlberg and Hemphill [23] concluded that in different
light environments it was possible to manipulate the can-
nabinoid content of C. sativa L. measured in young leaves.
The authors used colored filters to alter the light spectrum
and concluded that the THC content of leaves from plants
grown under shaded daylight and filtered red and blue
light did not differ significantly from the THC content in
daylight controls, while leaves from plants grown under
filtered green light and darkness contained significantly
lower levels of THC than those from plants grown in sun-
light. The research and equipment at that time was not
specific enough to thoroughly explain the effect of wave-
length areas on cannabinoid content and the effect of
lighting conditions on cannabis potency is still not clear.
The first study related to light quality and cannabinoid
content was conducted by Fairbairn and Liebann [24],
who concluded that no increase of cannabinoids was
found in a Nepalese variety grown in a greenhouse with
or without supplemental lighting (HPS or UV lamps).
Cannabis growers have been interested in UV light for a
long time; however, the relationship between cannabi-
noids and UV-B is not as direct as first proposed. In-
creased concentrations of THC, but not of other canna-
binoids, were found with UV-B treatment in both leaf and
floral tissues of drug-type plants [20, 25]. In contrast,
none of the cannabinoids in fiber-type plants were affect-
ed by UV-B radiation. In a more recent study, hemp
leaves were exposed to UV-C radiation and analyzed for
changes in secondary metabolite biosynthesis [26]. While
no remarkable change in the cannabinoid content was
observed, significant increases in dehydrostilbenes and
cinnamic acid amide derivatives were found. The limited
data available on the appropriate light source for cannabis
production underscore the importance of studying tech-
nological developments in horticultural lighting. The ob-
jective of this study was to examine the effects of light-
spectral quality on cannabis morphology and cannabi-
noid content in the female flowers under artificial growing
conditions. Two lighting technologies (HPS and LED)
and 3 different light spectra were used in this study.
Materials and Methods
Unrooted C. sativa L. cuttings, drug chemotype “G-170”
(CREA-CI, Rovigo, Italy), were inserted into rockwool cubes
(Grodan, Roermond, The Netherlands) and grown under T8 fluo-
rescent lights (LUMILUX T8 36/840 and FLUORA T8 36W; Os-
ram GmbH, Munich, Germany) for 2 weeks in a climate-con-
trolled growth chamber. Light intensity during the rooting period
was 160 µmol/m²/s measured with UPRTek PAR200 Spectrom-
eter (UPRTek, Miaoli County, Taiwan). The spectral photon dis-
tribution of the fluorescent light source is shown in Figure 1. The
cuttings were kept under 90% relative humidity at 25°C and ex-
posed to 24 h of light. Cuttings were watered with clean tap water
at the start of the rooting period. After 3 days, cuttings were sup-
plemented daily with the complete fertilizer Coco A and B (5%
NO3, 0.1% NH4+, 4% P2O5, 3% K2O, 7% CaO, 3% MgO, 2% SO3,
0.007% B, 0.001% Cu, 0.02% Fe DTPA, 0.0003% Fe EDTA, 0.01%
Mn, 0.002% Mo, 0.007% Zn, 0.5% fulvic and humic acid; CANNA
International BV, Oosterhout, The Netherlands) with 1.5 mS/cm
of electrical conductivity (EC) and pH 5.8. The adjustment of pH
was done by 40% nitric acid. After rooting, plants were transplant-
ed into 1.6-L pots containing coco peat (Coco Professional Plus,
CANNA International BV) and acclimatized for 8 days in a grow
room under HPS lights. Light intensity during the acclimatization
period at canopy height was 40–50 µmol/m2/s. During acclimati-
zation, plants were irrigated with a fertilization solution of EC 1.8
mS/cm and pH 5.8. After acclimatization period, 16 plants were
placed under each light treatment in the growth boxes, 48 plants
Med Cannabis Cannabinoids 2018;1:19–27
DOI: 10.1159/000489030
in total. Three different light sources were used in the experiment
as treatments: 2 LED light spectra, AP673L and NS1 (B100, Valoya
Oy; Helsinki, Finland), and 1 HPS light source (Philips Master T-
PIA Greenpower 600 W; Philips, Eindhoven, The Netherlands)
with magnetic ballast (ETI, Madrid, Spain). Light fixtures were
installed in grow tents (1.2 × 1.2 × 2 m) with a Mylar interior
(DR120, Secret Jardin; Manage, Belgium), equipped with an air
exhaust system to maintain the temperature at 26°C during the
light phase and a relative humidity of 60–70% (Vents VK 125,
Vents, Kiev, Ukraine). The light irradiance level was measured to
be 450 μmol/m2/s at canopy height when plants were transferred
into the grow tents. Lamps were raised during the experiment as
plants grew taller to maintain equal light intensities (450 μmol/
m2/s in the range of 400–700 nm) throughout the experiment. Per-
centages of wavelength areas in each spectrum are presented in
Table 1. During the acclimatization and vegetative phases, the pho-
toperiod was set to 18 h of light. The duration of the vegetative
phase was 13 days. Out of the 16 plants in each treatment, 9 plants
were selected for their good condition and uniformity and kept in
the grow tents for another 46 days under a short photoperiod
(12 h light and 12 h darkness) for flower induction. During the
short photoperiod, EC of the nutrient solution was increased from
1.8 to 2.0 mS/cm. The harvested plants were cut from the base and
dried at 30°C by hanging them upside down in a dark room
equipped with a dehumidifier. The plant height, stem weight, stem
diameter, leaf biomass, and flower biomass were recorded from
each plant. The floral cannabinoid concentrations (tetrahydrocan-
nabivarin [THCV], THC, CBD, and CBG) were measured using
gas chromatography (GC) according to the community method
for the quantitative determination of THC content in hemp variet-
ies (Reg. CE 796/2004) with some modifications. 40 mg of cured
and dried flower powder was weighed in a vial tube, and 4 mL of
internal standard/extracting solution (ethanol with 0.01% of praz-
epam) was added. The sample was sonicated for 15 min at 65°C,
and the extract centrifuged at 12,000 rpm for 5 min; a 1-mL aliquot
of the extract was then transferred from the tube to a 2-mL glass
GC vial. GC analyses were performed using a SHIMADZU GC-
2010 PLUS equipped with an autosampler (H-TA srl. model HT
300 series) and a flame ionization detector (FID-2010 PLUS). The
GC column was a 30 m × 0.25 mm I.D. with 0.25-µm film (RESTEK,
Relative intensity, %
380 400 500 600 700 780
Wavelenght, nm
Fluorescent tubes
Table 1. Spectral properties and the light intensities (in PAR, range
400–700 nm) under each light treatment
Light treatment
300–400 1% 0% 2%
400–500 8% 14% 24%
500–600 68% 20% 37%
600–700 21% 59% 33%
700–800 3% 7% 4%
400–700 PAR 96% 93% 94%
R:FR 2.80 6.07 10.05
B:G 0.29 1.76 0.74
B:R 0.10 0.26 0.80
NS1 and AP673L are LED lights; HPS, high-pressure sodium.
R:FR and B:G ratios are calculated according to Sellaro et al. [44]:
R:FR (650–670 nm/720–740 nm), B:G (420–490 nm/500–570 nm).
Fig. 1. Relative spectral photon flux of the light sources utilized.
Light Spectrum and Cannabis sativa L.
Med Cannabis Cannabinoids 2018;1:19–27
DOI: 10.1159/000489030
model Rxi-5ms). Data were recorded using Labsolutions LC/GC
5.51 (SHIMADZU) software. GC conditions used for the determi-
nation of cannabinoids were: H2 at 30 mL/min as carrier gas and
N2 as make up gas at 40 mL/min, and air at 400 mL/min, respec-
tively. The split flow rate was 15.8 mL/min, split ratio 25: 1, pres-
sure 12.76 psi, and purge flow rate 3 mL/min. 1-µL injections were
used; injector and detector temperatures were 280 and 300°C, re-
spectively. The isothermal oven temperature was 240°C and the
total run time was 15 min. Quantitation was achieved by determin-
ing peak area ratios of the analytes to the internal standard versus
concentrations in the range of 7.8–500 μg/mL. The growth exper-
iment was repeated twice. The first experiment took place in April
and May 2015 and the second experiment was conducted between
February and April in 2016. The average temperature and relative
humidity (mean ± standard deviation) in the first experiment were
23.6 ± 2.8°C and 64.5 ± 14% for treatments AP673L and NS1 or
24.7 ± 4.5°C and 56.1 ± 14.8% for HPS, respectively; during the
second experiment they were 22.8 ± 3.1°C and 61.9 ± 9.9% for
AP673L and NS1 or 23.6 ± 3.8°C and 51.4 ± 9.2% for HPS, respec-
tively. Statistical analysis for comparison of the different light
treatments was done using the Tukey test, with the level of signifi-
cance at 5%, while statistical comparisons between the experi-
ments were performed with one-way analysis of variance (ANO-
VA) in RStudio environment (version 3.3.3,
Results and Discussion
Plant Morphology and Flower Yield
The morphology of the flowering plants after 46 days
of the short-day period differed significantly between the
LED light treatments and the HPS treatment. Plants
aAP673L NS1
a A b B b B
bAP673L NS1
a A b B b B
cAP673L NS1
a A b A b A
dAP673L NS1
a A b B a B
eAP673L NS1
b B a A a A
fAP673L NS1
b B a A a A
gAP673L NS1
b B a A a B
hAP673L NS1
c C b B a A
iAP673L NS1
a A a A a A
Fig. 2. Bar graphs (mean and standard deviation) of plant parameters evaluated. a Height (cm). b Stem (g/plant).
c Flowers (g/plant). d Leaves (g/plant). e THC in flowers (%). f CBD in flowers (%). g THCV in flowers (%).
h CBG in flowers (%). i Yield of cannabinoids (g/plant). Different letters inside the bars show significant differ-
ences (Tukey HSD, p < 0.05). Solid lines and lower case letters are for trial 1, and dashed lines and upper case
letters are for trial 2. Significant differences between trials are represented by asterisks (*p < 0.05, **p < 0.01,
***p < 0.001).
Med Cannabis Cannabinoids 2018;1:19–27
DOI: 10.1159/000489030
grown under NS1 and AP673L were shorter and more
compact compared to those grown under the HPS treat-
ment. The plants grown under HPS were significantly
taller and had higher stem dry weight compared to those
grown under the LED light treatments (Fig.2a, b); no sig-
nificant differences were found between the two LED
spectra. Similar results between light treatments were
found in both experiments; however, the differences in
results between experiments were significant. In experi-
ment 1, plant height and dry stem weight ranged from
67.4 cm and 8.2 g/plant in HPS to 58.3 cm and 5.5 g in
AP673L, respectively. In experiment 2, plant height and
dry stem weight ranged from 79.2 cm and 14.2 g in HPS
to 54.5 cm and 7.6 g in AP673L, respectively These results
are consistent with previous studies by Tibbitts et al. [27]
and Wheeler et al. [28], who reported that plants grown
under sole HPS light may suffer from unbalanced mor-
phology expressed by excessive leaf and stem elongation.
This is due to the low R:FR ratio (i.e., the ratio between
red and far-red light) and low blue light emission of the
HPS lamp. The low R:FR ratio increases the activity of
several transcription factors that activate genes involved
in auxin biosynthesis leading to faster stem elongation
[29]. Blue light regulates morphological responses such as
shoot and internode elongation, shoot dry matter, and
leaf area expansion [30]. The flower yield was affected by
the light treatments. HPS plants had higher yields com-
pared to the LED treatments in experiment 1 (Fig.2c). In
the second experiment, the differences between light
treatments in flower yield were not statistically signifi-
cant; however, the same tendency was present (Fig.2c).
The flower yields in the second experiment were 26.6,
23.1, and 22.8 g for HPS, AP673L, and NS1, respectively.
The temperature variation between the two experiments
may have played a role in the case of HPS and NS1 treat-
ments in the yield results. Considering the AP673L treat-
ment, no differences of dry flower weight was observed
between experiments. Yields in the current study are con-
sistent with the recent horticultural studies on cannabis
[22], in which the yield per plant was 20.1 g under similar
lighting conditions to the HPS treatment in this experi-
ment. In experiment 1, the highest leaf dry weight was
measured in treatment NS1, ranging from 21.8 g (NS1) to
16.2 g (AP673L) (Fig.2d). In the second experiment, HPS
had the highest leaf dry weight, while the LED treatments
did not have a significant difference between them. In
experiment 2, the average leaf dry weight ranged from
30.6 g (HPS) to 23.6 g (AP673L). All light treatments
showed significant differences between the two experi-
ments and the experiments did not have a similar trend
between experiments. No differences in flowering time
between treatments were observed during the experi-
ments. This suggests that the fast-growing “G-170” geno-
type is insensitive to changes in the R:FR ratio, a response
commonly seen in long-day plants. No plant pathogens or
nutrient deficiency were found during the experiments.
Cannabinoid Yield
HPS resulted in a significant decline of THC concen-
tration in flowers compared to both LED treatments in
both experiments, while no significant differences be-
tween the two LED types were observed. The amount of
THC (% w/w) was highest in treatment NS1 and lowest
in treatment HPS in both experiments 1 and 2 (Fig.2e).
In experiment 1, HPS had 38% less (9.5%) THC com-
pared to NS1 (15.4%), in experiment 2, the equivalent
number was 26%. One-way ANOVA between the two ex-
periments showed a slight but significant (p < 0.05) dif-
ference in the THC concentration in treatments HPS and
AP673L but not in treatment NS1. The drop in the THC
concentration under HPS led to a corresponding decrease
in CBD, THCV, and especially CBG, which consequently
resulted in a significant increase in the THC proportion
compared to the LED treatments. HPS had a higher pro-
portion of THC in the total cannabinoid content (95.3%
in the first experiment and 96.0% in the second experi-
ment) compared to NS1 (94.3 and 94.9%). Moreover,
comparison between experiments showed a strong differ-
ence in the THC proportion under HPS and a slight but
significant (p < 0.05) difference in NS1, but not in AP673L.
The average CBD concentration showed a similar pattern
to the THC concentration (Fig.2f). The CBD concentra-
tion was highest in the LED treatments and lowest in the
HPS treatment in both experiments. In experiment 1,
HPS had 35% less (0.1%) CBD compared to NS1 (0.2%).
In experiment 2, the equivalent number was 29%. There
were no significant differences in CBD concentrations
between the experiments in any of the light treatments. In
experiment 1, the THCV concentration was significantly
higher in treatments AP673L (0.2%) and NS1 (0.2%)
compared to HPS (0.2%) (Fig.2g). In experiment 2, the
THCV concentrations in all treatments were significant-
ly lower than in experiment 1. AP673L resulted in the
highest concentration of THCV (0.1%), which was 35%
more than in the HPS treatment (0.1%) and 21% more
than in the NS1 treatment (0.1%). In experiment 1, the
average THCV purity showed no significant relationship
between light treatments and ranged from 1.7% under
HPS to 1.2% under NS1. In experiment 2, NS1 treatment
resulted in a lower THCV proportion (0.5%) compared
Light Spectrum and Cannabis sativa L.
Med Cannabis Cannabinoids 2018;1:19–27
DOI: 10.1159/000489030
to HPS (0.6%) or AP673L (0.7%) (data not shown). There
was a strong and significant difference in the THCV con-
tent and proportion values between the experiments in all
light treatments. Data obtained from this study indicate
that the light spectrum has an effect on the biosynthesis
of CBG (Fig.2h). The CBG concentration was highest in
the NS1 treatment in both experiments. NS1 had 207 and
107% more CBG compared to the HPS treatment in ex-
periments 1 and 2, respectively, and 63 and 21% more
than AP673L in experiments 1 and 2, respectively. In the
HPS and AP673L treatments, the results differed signifi-
cantly (p < 0.001) between the two experiments. CBG
proportion also showed a similar pattern to CBG content.
The NS1 treatment had the highest CBG purity in both
experiments (3.4 and 3.5%), followed by AP673L (2.6 and
2.9%) and HPS (1.8 and 2.3%). There were significant dif-
ferences in CBG proportion among the experimental tri-
als under the AP673L (p < 0.05) and HPS lamps (p < 0.01),
but not under NS1. There were no significant differences
found in the total yield of cannabinoids between the light
treatments or between the two experiments (Fig.2i). In
experiment 1, the highest cannabinoid yield per plant was
recorded under NS1 (4.3 g/plant) and the lowest under
HPS (3.2 g/plant). In experiment 2, results were following
a similar pattern and the highest cannabinoid yield was in
the NS1 treatment (3.8 g) and the lowest in the HPS treat-
ment (3.3 g).
The first enzyme in the cannabinoid pathway is a type
III PKS, named tetraketide synthase (TKS), which re-
quires the presence of a polyketide cyclase enzyme, named
olivetolic acid cyclase (OAC) to form olivetolic acid (OA)
[31]. OA reacts with geranyl pyrophosphate (GPP) by
GPP:olivetolate geranyltransferase, named CBGA syn-
thase (CBGAS), to form CBGA [32], which is converted
by oxidocyclase enzymes to the major cannabinoids
THCA and CBDA, the biogenic acids of THC and CBD
[33]. Unfortunately, no data are available regarding the
expression regulation of these genes. In higher plants,
the chalcone synthase (CHS) superfamily, a well-studied
plant type III PKS, is substantially light induced, resulting
in a variety of polyphenol scaffold accumulations [34].
Plants have evolved a complex photoreceptor system to
perceive red and far-red (phytochromes), green, blue,
UV-A (cryptochromes, phototropins, ZTL/FKF1/LKP2),
and UV-B light (UVR8) [35]. Photoreceptors activate
various signal transduction cascades to regulate light-de-
pendent responses via transcriptional factors and related
gene expression. For example, shorter wavelengths, in the
range of blue and UV light, are found to be the most ef-
fective in the accumulation of anthocyanins and flavo-
noids, often by increasing the expression of flavonoid
pathway genes or transcription factors [36, 37]. Strawber-
ries treated with blue light showed a significant increase
in anthocyanin content and transcript levels of FaCHS, a
key enzyme in the biosynthesis of flavonoid and antho-
cyanins [38]. In the same study, using overexpression, it
was shown that phototropin (PHOT2) was involved in
blue light-induced anthocyanin accumulation. Also,
cryptochromes (CRY1 and CRY2) control the blue light-
induced anthocyanin accumulation response [39, 40]. In
the present study, the highest CBG and THC concentra-
tions were measured in the NS1 treatment, which had the
highest portion of blue and UV-A wavelengths in the
spectrum compared to the other treatments. Blue and UV
wavelengths have been previously reported to have a pos-
itive effect on the synthesis of many secondary metabo-
lites in multiple species [30]. Mahlberg and Hemphill [23]
studied the effect of light intensity and light quality on
cannabinoid content in plants grown in greenhouse con-
ditions with altered spectra using different colored filters.
They concluded that a higher light intensity increased the
amount of THC, CBC, and CBN. According to their data,
blue and red light positively affected the THC accumula-
tion in leaves, whereas a green or dark environment had
a negative impact compared to the control treatment
(natural light). In the present study, the highest THC con-
tent measured in the flowers was under the NS1 treat-
ment and the lowest was under HPS. We suggest that the
blue and UV-A wavelengths positively affected THC syn-
thesis in treatments NS1 and AP673L, whereas the lack of
blue and UV-A irradiation in the HPS treatment resulted
in a lower amount of THC in flowers. The amount of blue
and UV-A irradiation was highest in the NS1 treatment;
however, the THC level difference between AP673L and
NS1 was not significant. This result could partially be ex-
plained by the high amount of green irradiation in the
NS1 treatment, which can negatively affect the THC syn-
thesis as also shown in the experiment by Mahlberg and
Hemphill [23]. Green light has also been shown to act
antagonistically to other blue light-induced responses,
such as stomatal closure [41] or anthocyanin accumula-
tion [42]. Another possible cause of drop in cannabinoid
concentration under the HPS lamp was the low R:FR ra-
tio. The R:FR ratio is known to play a key role in the shade
avoidance syndrome in plants through the mediation of
phytochromes [43]. In shaded conditions, plant photore-
ceptors activate shade-avoidance responses and reduce
the expression of the jasmonic acid signaling pathway
and other phytochemical biosynthesis, such as soluble
phenolics, anthocyanins, glucosinolates, and terpenoids
Med Cannabis Cannabinoids 2018;1:19–27
DOI: 10.1159/000489030
[29]. Our results suggest that manipulation of light qual-
ity during the flowering phase could be a useful tool to
improve the yield of THC and other cannabinoids in can-
nabis cultivation. We suggest that other complex mecha-
nisms mediated by the UV-A and blue wavelengths may
act synergistically to induce CBG accumulation in can-
nabis flowers, CBG being the precursor of other cannabi-
These two experiments are part of a trial series aimed
to study the effect of light conditions on cannabis growth.
In conclusion, the experiments presented here demon-
strate that the optimal spectrum for a specific photoperiod
scheme may have diverse beneficial effects on cannabis
growth, yield, and cannabinoid profile. Our study shows
that the light environment plays an important role not
only in plant size and stature but also in the accumulation
of cannabinoids. During a long photoperiod, a low R:FR
ratio is preferable to make more developed long cuttings,
while during a short photoperiod a high proportion of
blue irradiation is suitable to improve the medicinal value
of cannabis in terms of cannabinoid content. Manipula-
tion of the spectrum, an advantage of the LED technology,
offers better space utilization to support the heating and
cooling loads of growing buildings. LED lighting strate-
gies may be applied to improve the energy utilization and
carbon footprint of cannabis crop. The mechanisms un-
derlying the effect of UV-A/blue light wavelength on can-
nabinoid pathways require further elucidation.
The authors gratefully acknowledge all the staff members in-
volved in the study. This work was supported by fundings from
Valoya Oy.
Disclosure Statement
The authors declare that Valoya has funded the research activ-
ity. Dr. Stiina Kotiranta is employed at Valoya company.
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... Light is one of the crucial parameters for enclosed C. sativa production, as it greatly impacts the growth and its secondary metabolite accumulation of all plants through light intensity and spectra [16][17][18][19]. In the greenhouse industry, light-emitting diodes (LEDs) have been widely used for plant cultivation, as they are rated more energy-efficient over other conventional light sources, including high-pressure sodium (HPS) lamps [20,21]. ...
... As for red light, it has been associated with stem growth and rooting in other plants [2]. This seemed to translate to better cutting development in C. sativa exposed to high-red content lighting [18]. However, no studies have looked at the influence of monochromatic red or blue light on secondary metabolite production and biomass development in C. sativa. ...
... In other plants, the stimulation of internodal stretching and subsequent plant elongation by red-light induced shade avoidance response through phytochrome activation [47]. Redlight-induced vertical growth increases have been previously reported in C. sativa [18] and plant elongation of other greenhouse crops [48][49][50]. LEDs with a higher proportion of red wavelength increased plant height in other studies [26,33], but no study investigated the effect of amber light on cannabis plants. ...
Full-text available
Light is one of the most crucial parameters for enclosed cannabis (Cannabis sativa) production, as it highly influences growth, secondary metabolite production, and operational costs. The objective of this study was to investigate and evaluate the impact of six light spectra on C. sativa (‘Babbas Erkle Cookies’ accession) growth traits and secondary metabolite (cannabinoid and terpene) profiles. The light spectra evaluated included blue (430 nm), red (630 nm), rose (430 + 630 nm, ratio 1:10), purple (430 + 630 nm, ratio 2:1), and amber (595 nm) LED treatments, in addition to a high-pressure sodium (HPS, amber-rich light) treatment as a control. All the LED light treatments had lower fresh mean inflorescence mass than the control (HPS, 133.59 g plant−1), and monochromatic blue light yielded the least fresh inflorescence mass (76.39 g plant−1). Measurement of Δ9-tetrahydrocannabinol (THC) concentration (%) and total yield (g plant−1) showed how inflorescence mass and THC concentration need to be analyzed conjointly. Blue treatment resulted in the highest THC concentration (10.17% m/m), yet the lowest THC concentration per plant (1.44 g plant−1). The highest THC concentration per plant was achieved with HPS (2.54 g plant−1). As with THC, blue light increased cannabigerol (CBG) and terpene concentration. Conversely, blue light had a lesser impact on cannabidiol (CBD) biosynthesis in this C. sativa chemotype. As the combined effects of the light spectrum on both growth traits and secondary metabolites have important ramifications for the industry, the inappropriate spectral design could cause a reduction in cannabinoid production (20–40%). These findings show promise in helping producers choose spectral designs that meet specific C. sativa production goals.
... To improve growers' success and patient welfare, growing protocols that enhance yield quantity, chemical quality, and reproducibility are being developed (Bernstein et al., 2019b;Saloner et al., 2019;Eaves et al., 2020;Saloner and Bernstein, 2020, 2022aShiponi and Bernstein, 2021a,b) based on recently accumulated information on the plant responses. Recent findings demonstrate that numerous factors, including light intensity (Eaves et al., 2020;Rodriguez-Morrison et al., 2021), light quality (Magagnini et al., 2018;Danziger and Bernstein, 2021a), salt concentration (Yep et al., 2020), mineral nutrition Bernstein, 2021, 2022a,b;Shiponi and Bernstein, 2021b), pests and pathogens (Punja et al., 2019), affect phenotypic expression of cannabinoids in cannabis. ...
... To keep up with demand, various agricultural practices are used by the growers, but the effects of these newly adopted cultivation practices on product quality were usually not tested. Some agronomic practices such as mineral nutrition (Bernstein et al., 2019b;Bevan et al., 2021;Bernstein, 2021, 2022a,b;Shiponi and Bernstein, 2021b), light quality (Magagnini et al., 2018;Danziger and Bernstein, 2021a;Westmoreland et al., 2021), light intensity (Potter and Duncombe, 2012), and manipulation of the canopy architecture (Danziger and Bernstein, 2021b,c) were recently shown to change yield quantity and chemical quality in drugtype medical cannabis, and to affect the physiological state of the plant. Spatial variabilities in environmental conditions within the canopy are directly related to canopy density via effects on shading and air circulation (Morales et al., 2000;Boulard et al., 2017) and are considered to be a key to the lack of chemical standardization in cannabis cultivation. ...
... In cannabis, a single study used sub-canopy LED lights that were shown to increase yield quantity as well as the cannabinoid contents at the bottom third of the plant (Hawley et al., 2018). In addition, several studies evaluated different spectral properties on cannabis development, yield and its components showing differential response to light quality (Magagnini et al., 2018;Eaves et al., 2020;Bevan et al., 2021;Danziger and Bernstein, 2021a) as well light intensity (Potter and Duncombe, 2012). As light travels through the plant canopy, different wavelengths are absorbed by the plant organs altering its spectrum as well as intensity (Kasperbauer, 1971). ...
Full-text available
A major challenge for utilizing cannabis for modern medicine is the spatial variability of cannabinoids in the plant, which entail differences in medical potency. Since secondary metabolism is affected by environmental conditions, a key trigger for the variability in secondary metabolites throughout the plant is variation in local micro-climates. We have, therefore, hypothesized that plant density, which is well-known to alter micro-climate in the canopy, affects spatial standardization, and concentrations of cannabinoids in cannabis plants. Canopy density is affected by shoot architecture and by plant spacing, and we have therefore evaluated the interplay between plant architecture and plant density on the standardization of the cannabinoid profile in the plant. Four plant architecture modulation treatments were employed on a drug-type medicinal cannabis cultivar, under a density of 1 or 2 plants/m ² . The plants were cultivated in a naturally lit greenhouse with photoperiodic light supplementation. Analysis of cannabinoid concentrations at five locations throughout the plant was used to evaluate treatment effects on chemical uniformity. The results revealed an effect of plant density on cannabinoid standardization, as well as an interaction between plant density and plant architecture on the standardization of cannabinoids, thus supporting the hypothesis. Increasing planting density from 1 to 2 plants/m ² reduced inflorescence yield/plant, but increased yield quantity per area by 28–44% in most plant architecture treatments. The chemical response to plant density and architecture modulation was cannabinoid-specific. Concentrations of cannabinoids in axillary inflorescences from the bottom of the plants were up to 90% lower than in the apical inflorescence at the top of the plant, considerably reducing plant uniformity. Concentrations of all detected cannabinoids in these inflorescences were lower at the higher density plants; however, cannabinoid yield per cultivation area was not affected by neither architecture nor density treatments. Cannabigerolic acid (CBGA) was the cannabinoid least affected by spatial location in the plant. The morpho-physiological response of the plants to high density involved enhanced leaf drying at the bottom of the plants, increased plant elongation, and reduced cannabinoid concentrations, suggesting an involvement of chronic light deprivation at the bottom of the plants. Therefore, most importantly, under high density growth, architectural modulating treatments that facilitate increased light penetration to the bottom of the plant such as “Defoliation”, or that eliminated inflorescences development at the bottom of the plant such as removal of branches from the lower parts of the plant, increased chemical standardization. This study revealed the importance of plant density and architecture for chemical quality and standardization in drug-type medical cannabis.
... GC-MS was employed in an interesting study recently [46] where the natural and artificial lighting on cannabinoid metabolism were analyzed. Sp treatments of cannabis crops with 3 different light spectra, high-pressure sodiu AP673L (LED), and NS1 (LED) were investigated [46]. ...
... GC-MS was employed in an interesting study recently [46] where the natural and artificial lighting on cannabinoid metabolism were analyzed. Sp treatments of cannabis crops with 3 different light spectra, high-pressure sodiu AP673L (LED), and NS1 (LED) were investigated [46]. Results explored h treatments affected cannabis morphology and its CBG, CBD and THC content, ...
... GC-MS was employed in an interesting study recently [46] where the effects of natural and artificial lighting on cannabinoid metabolism were analyzed. Specifically, treatments of cannabis crops with 3 different light spectra, high-pressure sodium (HPS), AP673L (LED), and NS1 (LED) were investigated [46]. ...
Full-text available
Cannabis (Cannabis sativa L.), also known as hemp, is one of the oldest cultivated crops, grown for both its use in textile and cordage production, and its unique chemical properties. However, due to the legislation regulating cannabis cultivation, it is not a well characterized crop, especially regarding molecular and genetic pathways. Only recently have regulations begun to ease enough to allow more widespread cannabis research, which, coupled with the availability of cannabis genome sequences, is fuelling the interest of the scientific community. In this review, we provide a summary of cannabis molecular resources focusing on the most recent and relevant genomics, transcriptomics and metabolomics approaches and investigations. Multi-omics methods are discussed, with this combined approach being a powerful tool to identify correlations between biological processes and metabolic pathways across diverse omics layers, and to better elucidate the relationships between cannabis sub-species. The correlations between genotypes and phenotypes, as well as novel metabolites with therapeutic potential are also explored in the context of cannabis breeding programs. However, further studies are needed to fully elucidate the complex metabolomic matrix of this crop. For this reason, some key points for future research activities are discussed, relying on multi-omics approaches. ******************************************************************************* Keywords: cannabis; genomics; metabolomics; multi-omics; transcriptomics
... On the other hand, Hibiscus moscheutos encapsulated nodal segments stored at 5 • C for 6 months showed no regrowth differences between light and dark storage whereas light exposure during 25 • C storage led to advance regrowth rates [34]. This finding is aligned with commercial cannabis propagation practices that involve light exposure to stem cuttings for extended hours (18 h) for the first 21 days to induce breakage of axillary bud dormancy and initiate sprouting [35]. Our findings showed that light play a pivotal role on viability of cannabis synseeds during medium-term storage. ...
... On the other hand, Hibiscus moscheutos encapsulated nodal segments stored at 5 °C for 6 months showed no regrowth differences between light and dark storage whereas light exposure during 25 °C storage led to advance regrowth rates [34]. This finding is aligned with commercial cannabis propagation practices that involve light exposure to stem cuttings for extended hours (18 h) for the first 21 days to induce breakage of axillary bud dormancy and initiate sprouting [35]. Our findings showed that light play a pivotal role on viability of cannabis synseeds during medium-term storage. ...
Full-text available
Indoor cannabis (Cannabis sativa) cultivation has been rapidly increasing in many countries after legalization. Besides conventional propagation through cuttings, synthetic seed production provides a competent system for mass propagation, germplasm conservation and international exchange of genetic materials. The present study developed a reliable protocol for cannabis synthetic seed production using encapsulation of nodal segments derived from in vitro or in vivo sources. Synthetic seeds were produced in 3% sodium alginate and 75 mM calcium chloride in Murashige and Skoog (MS) medium and stored under various environmental conditions for up to 150 days. The plantlets regrowth efficiency was monitored on culture media up to 30 days after the storage period. Regrowth rates of 70% and 90% were observed in synthetic seeds from in vitro and in vivo-derived sources, respectively, when stored in 6 °C under 50 μmol s−1 m−2 light for 150 days. Furthermore, addition of acetylsalicylic acid (ASA) to the encapsulation matrix not only postponed precocious germination of synthetic seeds at 22 °C, but also improved the regrowth rate of in vivo-derived synthetic seeds to 100% when they were stored in 6 °C under light. Exposure to light during storage significantly increased shoot length of regrown synseeds when compared to those stored in darkness. This difference in shoot growth disappeared when synseeds were treated with 25 µM ASA. All regenerated plantlets were rooted and acclimatized in sterile rockwool plugs without morphological changes.
... In the context of light, the action spectrum [38] in the range of 400-700 nm is of fundamental importance, as it defines the photosynthetically active radiation (PAR) and includes all wavelengths, except FR (>700 nm). Considering the spectral distributions in recent publications, it is noticeable that mainly full-spectrum lights, which trigger multiple photoreceptors, have been used [39,40]. Nevertheless, some key messages have already been established, such as an increase in visible light, which includes the blue, green and red spectra, which are considered to increase cannabinoids [41,42]. ...
... However, in the study of [42], spectra at flowering induction were changed and different PARs were applied under each treatment, making an interpretation almost impossible; in addition, there was no statistical evaluation for the single terpenes. The most recent Cannabis sativa L. publications focus mainly on cannabinoids, using different methodological approaches and showing widely differing results [39,65,66]. For example, [67] showed a strain-specific interaction for cannabinoids in three different strains, each under four different light sources, and it was not possible to make a clear statement on the influence of light. ...
Full-text available
Cannabis is one of the oldest cultivated plants, but plant breeding and cultivation are restricted by country-specific regulations. The plant has gained interest due to its medically important secondary metabolites, cannabinoids and terpenes. Besides biotic and abiotic stress factors, secondary metabolism can be manipulated by changing light quality and intensity. In this study, three morphologically different cannabis strains were grown in a greenhouse experiment under three different light spectra with three real light repetitions. The chosen light sources were as follows: a CHD Agro 400 ceramic metal-halide lamp with a sun-like broad spectrum and an R:FR ratio of 2.8, and two LED lamps, a Solray (SOL) and an AP67, with R:FR ratios of 13.49 and 4, respectively. The results of the study indicated that the considered light spectra significantly influenced CBDA and terpene concentrations in the plants. In addition to the different light spectra, the distributions of secondary metabolites were influenced by flower positions. The distributions varied between strains and indicated interactions between morphology and the chosen light spectra. Thus, the results demonstrate that secondary metabolism can be artificially manipulated by the choice of light spectrum, illuminant and intensity. Furthermore, the data imply that, besides the cannabis strain selected, flower position can have an impact on the medicinal potencies and concentrations of secondary metabolites.
... The high light intensity with proper photoperiod is needed during the vegetative growth stage to maximize cannabis growth and to initiate the budding (Arnold, 2013). In this context, the quality of LED had a significant impact on cannabis production as LED fixtures can be made with unique spectra that have the potential to increase the quality and targetted yield (Magagnini et al., 2018;Westmoreland et al., 2021). Moreover, a considerable change in shoot architecture, inflorescence mass and the alteration in the content of cannabinoids, terpenes, and other bioactive properties of the plant extracts may significantly vary on LED light composition (Namdar et al., 2019). ...
... During the initial stage of the cannabinoid pathway, a type III PKS enzyme named tetraketide synthase (TKS) activates with the help of olivetolic acid cyclase (OAC), a polyketide cyclase enzyme to form olivetolic acid (OA). OA reacts with geranyl pyrophosphate (GPP) with the help of CBGA synthase (CBGAS), a GPP: olivetolategeranyltransferase, to form CBGA. Later CBGA converts to THCA and CBDA, the biogenic acids of THC and CBD, by oxidocyclase enzymes (Fellermeier and Zenk, 1998;Sirikantaramas et al., 2007;Gagne et al., 2012;Magagnini et al., 2018). Despite little or no data available regarding the expression of these genes, in higher plants, some type III PKS such as chalone synthase (CHS), related to polyphenol accumulation, was substantially induced by light (Flores-Sanchez and Verpoorte, 2008). ...
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Manipulation of growth and development of cannabis (Cannabis sativa L.) has received considerable interest by the scientific community due to its high value in medicinal and recreational use worldwide. This study was conducted to investigate the effects of LED spectral changes on reactive oxygen species (ROS) and cannabinoid accumulation by provoking growth, pigmentation, photosynthesis, and secondary metabolites production of cannabis grown in an indoor environment. After three weeks of vegetative growth under greenhouse condition, plants were further grown for 90 days in a plant factory treated with 4 LED light compositions with a canopy-level photosynthetic photon flux density (PPFD) of 300 μmol m−2 s−1 for 16 h. Photosynthetic pigments and photosynthetic rate were linearly increased up to 60 days and then sharply decreased which was found most prominent in L3: MB 240 (Red 85% + Blue 15%) and L4: PF 240 (Red 70% + Blue 30%) LED light compositions. A high concentration of H2O2 was also observed in L3 and L4 treatments which provoked lipid peroxidation in later growth stage. In addition, higher accumulation of cannabinoid was observed under L4 treatment in most cases. It is also evident that higher ROS created a cellular stress in plant as indicated by higher osmolyte synthesis and enzyme activity which initiate quick maturation along with higher cannabinoids accumulation in cannabis plant. Therefore, it can be concluded that ROS metabolism has a crucial role in morpho-physiological acclimation and cannabinoid accumulation in hemp plants. The findings of this study provide further insight on the use of LED light to maximize the production of cannabinoid.
... Further, UV absorption of THC does not confer a clear ecological advantage relative to other major cannabinoids, which have similar [e.g., cannabidiol (CBD)] or greater [e.g., cannabichromene (CBC) and cannabinol (CBN)] UV absorption than THC (Pate, 1994;Hazekamp et al., 2005;de Backer et al., 2009). Despite a lack of contemporary published scientific studies on the effects of UV exposure on cannabinoid content (Magagnini et al., 2018), there is a popular belief that UV exposure can substantially enhance cannabinoid contentparticularly THC -in inflorescence tissues in modern cannabis genotypes. Genotypic predisposition to producing THC is also an important consideration since inflorescence THC content may be many times higher in modern vs. older cannabis genotypes (Dujourdy and Besacier, 2017). ...
... Frontiers in Plant Science 02 shorter wavelengths in the blue (400-500 nm) wavebands have also been implicated in altering the cannabis inflorescence chemical composition (Magagnini et al., 2018;Bilodeau et al., 2019) and mediating cellular repair provoked by UVB damage in other species (Krizek, 2004), sometimes called photoreactivation (Gill et al., 2015). Rodriguez-Morrison et al. (2021b) found only deleterious effects on cannabis morphology, physiology, yield, and quality when two chemotype II cannabis cultivars were exposed to various levels of short wavelength UVB provided by LEDs with a peak wavelength of 287 nm. ...
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Cannabis (Cannabis sativa) flourishes under high light intensities (LI); making it an expensive commodity to grow in controlled environments, despite its high market value. It is commonly believed that cannabis secondary metabolite levels may be enhanced both by increasing LI and exposure to ultraviolet radiation (UV). However, the sparse scientific evidence is insufficient to guide cultivators for optimizing their lighting protocols. We explored the effects of LI and UV exposure on yield and secondary metabolite composition of a high Δ9-tetrahydrocannabinol (THC) cannabis cultivar ‘Meridian’. Plants were grown under short day conditions for 45 days under average canopy photosynthetic photon flux densities (PPFD, 400–700 nm) of 600, 800, and 1,000 μmol m–2 s–1, provided by light emitting diodes (LEDs). Plants exposed to UV had PPFD of 600 μmol m–2 s–1 plus either (1) UVA; 50 μmol m–2 s–1 of UVA (315–400 nm) from 385 nm peak LEDs from 06:30 to 18:30 HR for 45 days or (2) UVA + UVB; a photon flux ratio of ≈1:1 of UVA and UVB (280–315 nm) from a fluorescent source at a photon flux density of 3.0 μmol m–2 s–1, provided daily from 13:30 to 18:30 HR during the last 20 days of the trial. All aboveground biomass metrics were 1.3–1.5 times higher in the highest vs. lowest PPFD treatments, except inflorescence dry weight – the most economically relevant parameter – which was 1.6 times higher. Plants in the highest vs. lowest PPFD treatment also allocated relatively more biomass to inflorescence tissues with a 7% higher harvest index. There were no UV treatment effects on aboveground biomass metrics. There were also no intensity or UV treatment effects on inflorescence cannabinoid concentrations. Sugar leaves (i.e., small leaves associated with inflorescences) of plants in the UVA + UVB treatment had ≈30% higher THC concentrations; however, UV did not have any effect on the total THC in thesefoliar tissues. Overall, high PPFD levels can substantially increase cannabis yield, but we found no commercially relevant benefits of adding UV to indoor cannabis production.
We are currently witnessing a shift in the approach to combat traffic and consumption of illegal harmful drugs, being cannabis legalization a prominent example. In this paper, we study how to optimally regulate the market for cannabis, in a setting where consumers differ in their utility from consumption of the psychoactive component of cannabis, THC, and suffer from misperception of the health damage it causes. We analyze this problem through a vertical differentiation model, where a black market firm and a public firm compete in prices and qualities (THC content). A paternalistic government would like to correct for the misperceived health damage caused by cannabis consumption, as well as to reduce the size of the black market. It is the undesirability of black market profits what explains that the first-best allocation cannot be decentralized. We find two possible equilibria, depending on whether the public firm serves those consumers with the highest or lowest willingness to pay for quality. Paradoxically, when the public firm serves those consumers with higher taste for THC, a lower average health damage is achieved together with a better economic result for the public firm.
Cannabis sativa L. has raised a lot of interest in recent years, due to the different utilities of the plant, being useful in different types of industries, as well as the discovery of possible therapeutic utilities of different secondary metabolites of the plant. This chapter presents the effect of the different environmental factors on the different vital phases of the plant, emphasizing its effects on its secondary metabolism. Secondly, we will review different agronomic techniques related to irrigation, the behavior of the plant in water scarcity scenarios, mineral nutrition and the use of different phytohormones and chemical supplements, focusing on their influence on the secondary metabolism of C. sativa L. Finally, the use of the novel biostimulants and biocontrols in this crop and their future prospects are discussed.
The cannabis (Cannabis sativa L.) genome is highly heterozygous and, to retain genetic identity, clonal propagation of cultivars is very common. Establishing controlled environments, often involving multiple locations throughout a single grow, is critical for reliably generating materials to be used in research and production. In this article, we break down different periods of the grow cycle, such as cloning, hardening (optional), vegetative growth, flowering growth, and harvest, into individual steps. We are including images and videos for an in-depth coverage of methodological details. We are providing a list of equipment, supplies, reagents, and other resources to help with planning a grow experiment. Finally, we are discussing considerations for different aspects of controlled environments, including lighting, fertilizer regimes, and integrated pest management. With this article, it is our goal to empower researchers to reliably generate disease-free cannabis material suitable for genetic and biochemical studies that require full control of environmental factors.
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The aim of this study was to investigate the effect of red (600-700 nm, peak 660), blue (400-500 nm, peak 450) and white light on the morphological and photosynthetic qualities of Cannabis sativa L. The two treatments were the white light (WL), and a combination of blue red lights (BR). Plants grown under WL were 23% taller than those grown under the BR light emitting diodes. The leaf area was also greater under WL than BR by 20%. The number of lateral branches and length of dominant lateral branch weren´t significantly different. It was concluded WL that emit a full spectrum of light affects plant growth and development better than BR light. The quantum efficiency ranged from 0.81 to 0.845 indicating the plants were not in stress.
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p>Research in the last decades has widely investigated the anti-oxidant properties of natural products as a therapeutic approach for the prevention and the treatment of oxidative-stress related disorders. In this context, several studies were aimed to evaluate the therapeutic potential of phytocannabinoids, the bioactive compounds of Cannabis sativa . Here, we examined the anti-oxidant ability of Cannabigerol (CBG), a non-psychotropic cannabinoid, still little known, into counteracting the hydrogen peroxide (H2O2)-induced oxidative stress in murine RAW264.7 macrophages. In addition, we tested selective receptor antagonists for cannabinoid receptors and specifically CB1R (SR141716A) and CB2R (AM630) in order to investigate through which CBG may exert its action. Taken together, our in vitro results showed that CBG is able to counteract oxidative stress by activation of CB2 receptors. CB2 antagonist pre-treatment indeed blocked the protective effects of CBG in H2O2 stimulated macrophages, while CB1R was not involved. Specifically, CBG exhibited a potent action in inhibiting oxidative stress, by down-regulation of the main oxidative markers (iNOS, nitrotyrosine and PARP-1), by preventing IκB-α phosphorylation and translocation of the nuclear factor-κB (NF-κB) and also via the modulation of MAP kinases pathway. On the other hand, CBG was found to increase anti-oxidant defense of cells by modulating superoxide dismutase-1 (SOD-1) expression and thus inhibiting cell death (results focused on balance between Bax and Bcl-2). Based on its antioxidant activities, CBG may hold great promise as an anti-oxidant agent and therefore used in clinical practice as a new approach in oxidative-stress related disorders.</p
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The effect of light quality on the growth and development of geranium (cv. Century Rose) was examined in three different glasshouse temperatures i.e., 16°C, 21°C or 24°C under natural light conditions. To alter light quality, five different colour filters i.e. blue and red absorbing (088), blue absorbing (101), two partially blue absorbing (109 and 110) and red absorbing (117) were used, with clear polythene as a control. Spectral filters as well as temperature considerably affected different growth parameters. Plant height, internode length, leaf area and flowering were significantly affected by the spectral filters as well as the temperature. In terms of the effects of the presumed photoreceptors, the data analysis indicated that plant height and internode length in geranium was regulated by the action of cryptochrome (blue acting photoreceptor) and not the phytochrome. However, time to flowering was affected by a combined action of phytochrome and cryptochrome, since the filters with high blue transmission and high phytochrome photoequilibrium resulted in early flowering. Simple models were created, through applying multiple regression technique, to predict the influence of spectral quality and temperature on plant height, internode length and time to flowering in geranium. The models could be applied to simulate the potential benefits of spectral quality and temperature in manipulation of growth and flowering in geranium. These will help in designing greenhouse cladding materials for regulation of plant growth in an environment friendly manner.
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To investigate how light quality influences tomato (Solanum lycopersicum L) seedlings, we examined changes in plant growth, chloroplast ultrastructure, photosynthetic parameters and some photosynthesis-related genes expression levels. For this, tomato plants were grown under different light qualities with the same photosynthetic photon flux density: red (R), blue (B), yellow (Y), green (G) and white (W) lights. Our results revealed that, compared with plants grown under W light, the growth of plants grown under monochromatic lights was inhibited with the growth reduction being more significant in the plants grown under Y and G lights. However, the monochromatic lights had their own effects on the growth and photosynthetic function of tomato seedlings. The plant height was reduced under blue light, but expression of rbcS, rbcL, psbA, psbB genes was up-regulated, and the ΦPSII and electron transport rate (ETR) values were enhanced. More starch grains were accumulated in chloroplasts. The root elongation, net photosynthetic rate (Pn), NPQ and rbcS and psbA genes expression were promoted under red light. Yellow light- and green light-illuminated plants grew badly with their lower Rubisco content and Pn value observed, and less starch grains accumulated in chloroplast. However, less influence was noted of light quality on chloroplast structure. Compared with yellow light, the values of ΦPSII, ETR, qP and NPQ of plants exposed to green light were significantly increased, suggesting that green light was beneficial to both the development of photosynthetic apparatus to some extent.
As studies continue to reveal favorable findings for the use of cannabidiol in the management of childhood epilepsy syndromes and other disorders, best practices for the large-scale production of Cannabis are needed for timely product development and research purposes. The processes of two institutions with extensive experience in producing large-scale cannabidiol chemotype Cannabis crops—GW Pharmaceuticals and the University of Mississippi—are described, including breeding, indoor and outdoor growing, harvesting, and extraction methods. Such practices have yielded desirable outcomes in Cannabis breeding and production: GW Pharmaceuticals has a collection of chemotypes dominant in any one of eight cannabinoids, two of which—cannabidiol and cannabidivarin—are supporting epilepsy clinical trial research, whereas in addition to a germplasm bank of high-THC, high-CBD, and intermediate type cannabis varieties, the team at University of Mississippi has established an in vitro propagation protocol for cannabis with no detectable variations in morphologic, physiologic, biochemical, and genetic profiles as compared to the mother plants. Improvements in phytocannabinoid yields and growing efficiency are expected as research continues at these institutions. This article is part of a Special Issue entitled “Cannabinoids and Epilepsy”.
Light is one of the key environmental factors that affect anthocyanin biosynthesis. However, the underlying molecular mechanism remains unclear, and many problems regarding phenotypic change and corresponding gene regulation have not been solved. In the present study, comparative analyses of light-induced anthocyanin accumulation and gene expression between the ray florets and leaves were performed in Chrysanthemum ×morifolium ‘Purple Reagan’. After contrasting the variations in the flower color phenotype and relative pigment content, as well as expression patterns of structural and regulator genes responsible for anthocyanin biosynthesis and photoreceptor between different plant organs under light and dark conditions, we concluded that (1) both the capitulum and foliage are key organs responding to light for chrysanthemum coloration; (2) compared with flavones, shading makes a greater decrease on the anthocyanins accumulation; (3) most of the structural and regulatory genes in the light-induced anthocyanin pathway specifically express in the ray florets; and (4) CmCHS, CmF3H, CmF3'H, CmANS, CmDFR, Cm3GT, CmMYB5-1, CmMYB6, CmMYB7-1, CmbHLH24, CmCOP1 and CmHY5 are key genes for light-induced anthocyanin biosynthesis in chrysanthemum ray florets, while on the transcriptional level, the expressions of CmPHYA, CmPHYB, CmCRY1a, CmCRY1b and CmCRY2 are insignificantly changed. Moreover, the inferred comprehensive effect of multiple signals on the accumulation of anthocyanins and transmission channel of light signal that exist between the leaves and ray florets were further discussed. These results further our understanding of the relationship between the gene expression and light-induced anthocyanin biosynthesis, and lay foundations for the promotion of the molecular breeding of novel flower colors in chrysanthemums.
Cannabis sativa has been employed for thousands of years, primarily as a source of a stem fiber (both the plant and the fiber termed “hemp”) and a resinous intoxicant (the plant and its drug preparations commonly termed “marijuana”). Studies of relationships among various groups of domesticated forms of the species and wild-growing plants have led to conflicting evolutionary interpretations and different classifications, including splitting C. sativa into several alleged species. This review examines the evolving ways Cannabis has been used from ancient times to the present, and how human selection has altered the morphology, chemistry, distribution and ecology of domesticated forms by comparison with related wild plants. Special attention is given to classification, since this has been extremely contentious, and is a key to understanding, exploiting and controlling the plant. Differences that have been used to recognize cultivated groups within Cannabis are the results of disruptive selection for characteristics selected by humans. Wild-growing plants, insofar as has been determined, are either escapes from domesticated forms or the results of thousands of years of widespread genetic exchange with domesticated plants, making it impossible to determine if unaltered primeval or ancestral populations still exist. The conflicting approaches to classifying and naming plants with such interacting domesticated and wild forms are examined. It is recommended that Cannabis sativa be recognized as a single species, within which there is a narcotic subspecies with both domesticated and ruderal varieties, and similarly a non-narcotic subspecies with both domesticated and ruderal varieties. An alternative approach consistent with the international code of nomenclature for cultivated plants is proposed, recognizing six groups: two composed of essentially non-narcotic fiber and oilseed cultivars as well as an additional group composed of their hybrids; and two composed of narcotic strains as well as an additional group composed of their hybrids.
Ultra-violet (UV) and blue radiations are perceived by plants through several photoreceptors. They regulate a large range of processes throughout plant life. Along with red radiations, they are involved in diverse photomorphogenic responses, e.g. seedling development, branching or flowering. In this paper, we present an overview of UV- and blue-radiations signaling pathways in some key physiological processes and describe effects of plant exposure to these wavelengths on phenotype as well as on contents in useful metabolites and resistance to bio aggressors. Taking these knowledge into account, we finally discuss possible applications of the use of such radiations to improve plant production in horticulture.
Aims To provide an overview of: demographic characteristics; experiences with growing cannabis; methods and scale of growing operations; reasons for growing; personal use of cannabis and other drugs; participation in cannabis and other drug markets; contacts with the criminal justice system for respondents to an online survey about cannabis cultivation drawn from eleven countries (N = 6530). Important similarities and differences between the national samples recruited will be discussed. Method This paper utilizes data from the online web survey of predominantly ‘small-scale’ cannabis cultivators in eleven countries conducted by the Global Cannabis Cultivation Research Consortium (GCCRC). Here we focus primarily on descriptive statistics to highlight key similarities and differences across the different national samples. Findings Overall there was a great deal of similarity across countries in terms of: demographic characteristics; experiences with growing cannabis; methods and scale of growing operations; reasons for growing; use of cannabis and other drugs; participation in cannabis and other drug markets, and; contacts with the criminal justice system. In particular, we can recognise that a clear majority of those small-scale cannabis cultivators who responded to our survey are primarily motivated for reasons other than making money from cannabis supply and have minimal involvement in drug dealing or other criminal activities. These growers generally come from ‘normal’ rather than ‘deviant’ backgrounds. Some differences do exist between the samples drawn from different countries suggesting that local factors (political, geographical, cultural etc.) may have some influence on how small-scale cultivators operate, although differences in recruitment strategies in different countries may also account for some differences observed.