Abstract
Cultivation of hemp ( Cannabis sativa L.) in tropical and subtropical regions can be challenging if the flowering behavior of a given cultivar is unknown, poorly understood, or not accurately selected for the photoperiod. Identifying cultivars adapted to local environmental conditions is key to optimizing hemp vegetative and flowering performance. We investigated the effects of varying light cycles in regulating extension growth and flowering response of 15 essential oil and 12 fiber/grain hemp cultivars both indoors and outdoors. Plants were subjected to 11 photoperiods in the controlled rooms ranging from 12 to 18 h, and natural day length in the field. The critical photoperiod threshold was identified for seven essential oil cultivars and two fiber/grain cultivars. “Cherry Wine-CC,” “PUMA-3,” and “PUMA-4” had the shortest critical day length between 13 h 45 min and 14 h. The flowering of essential oil cultivars was generally delayed by 1–2 days when the photoperiod exceeded 13 h compared with 12 h, and flowering was further delayed by 7–8 days when the photoperiod exceeded 14 h. In fiber/grain cultivars, flowering was generally delayed by 1–3 days when the day length exceeded 14 h. Flowering for most essential oil cultivars was delayed by 5–13 days under a 14-h photoperiod compared with 13 h 45 min, suggesting a photoperiod difference as little as 15 min can significantly influence the floral initiation of some essential oil cultivars. Cultivars represented by the same name but acquired from different sources can perform differently under the same environmental conditions, suggesting genetic variation among cultivars with the same name. Average days to flower of fiber/grain cultivars was correlated with reported cultivar origin, with faster flowering occurring among northern cultivars when compared with southern cultivars. Plant height generally increased as the day length increased in essential oil cultivars but was not affected in fiber/grain cultivars. In addition, civil twilight of ~2 μmol·m −2 ·s −1 was discovered to be biologically effective in regulating hemp flowering. Collectively, we conclude that most of the essential oil cultivars and some southern fiber/grain cultivars tested express suitable photoperiods for tropical and sub-tropical region cultivation.
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Claims 15
Claim · model-written summary
Critical photoperiod thresholds were identified for seven essential oil cultivars.
- Taxon
- hemp
Cannabis sativa subsp. sativat0 - Material
- essential oil cultivarse0
- Outcome
- critical photoperiod thresholde0
- Value
- sevene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The critical photoperiod threshold was identified for seven essential oil cultivars”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Critical photoperiod thresholds were identified for two fiber/grain cultivars.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- fiber/grain cultivarse1
- Outcome
- critical photoperiod thresholde1
- Value
- twoe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“two fiber/grain cultivars”
e1“The critical photoperiod threshold was identified for seven essential oil cultivars and two fiber/grain cultivars”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Cherry Wine-CC, PUMA-3 and PUMA-4 had the shortest critical day length, 13 h 45 min to 14 h.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- “Cherry Wine-CC,” “PUMA-3,” and “PUMA-4”e0
- Outcome
- critical day lengthe0
- Direction
- shorteste0
- Value
- between 13 h 45 min and 14 he0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0““Cherry Wine-CC,” “PUMA-3,” and “PUMA-4” had the shortest critical day length between 13 h 45 min and 14 h”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Essential oil cultivar flowering was delayed 1–2 days above 13 h versus 12 h.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- essential oil cultivarse0
- Treatment
- photoperiod exceeded 13 he0
- Outcome
- floweringe0
- Direction
- delayede0
- Value
- 1–2 dayse0
- Comparator
- 12 he0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The flowering of essential oil cultivars was generally delayed by 1–2 days when the photoperiod exceeded 13 h compared with 12 h”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Essential oil cultivar flowering was further delayed 7–8 days above 14 h.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- essential oil cultivarse1
- Treatment
- photoperiod exceeded 14 he0
- Outcome
- floweringe0
- Direction
- delayede0
- Value
- 7–8 dayse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“flowering was further delayed by 7–8 days when the photoperiod exceeded 14 h”
e1“The flowering of essential oil cultivars was generally delayed”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Fiber/grain cultivar flowering was delayed 1–3 days above 14 h.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- fiber/grain cultivarse0
- Treatment
- day length exceeded 14 he0
- Outcome
- floweringe0
- Direction
- delayede0
- Value
- 1–3 dayse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In fiber/grain cultivars, flowering was generally delayed by 1–3 days when the day length exceeded 14 h”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Most essential oil cultivars flowered 5–13 days later at 14 h than at 13 h 45 min.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- essential oil cultivarse0
- Treatment
- 14-h photoperiode0
- Outcome
- Floweringe0
- Direction
- delayede0
- Value
- 5–13 dayse0
- Comparator
- 13 h 45 mine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Flowering for most essential oil cultivars was delayed by 5–13 days under a 14-h photoperiod compared with 13 h 45 min”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Same-named cultivars from different sources performed differently under the same conditions.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- Cultivars represented by the same namee0
- Outcome
- perform differentlye0
- Direction
- differentlye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cultivars represented by the same name but acquired from different sources can perform differently under the same environmental conditions”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Average days to flower in fiber/grain cultivars correlated with reported cultivar origin.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- fiber/grain cultivarse0
- Outcome
- Average days to flowere0
- Setting
- reported cultivar origine0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Average days to flower of fiber/grain cultivars was correlated with reported cultivar origin”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Northern fiber/grain cultivars flowered faster than southern cultivars.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- northern cultivarse0
- Outcome
- floweringe0
- Direction
- fastere0
- Comparator
- southern cultivarse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“faster flowering occurring among northern cultivars when compared with southern cultivars”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Essential oil cultivar height generally increased with day length.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- essential oil cultivarse0
- Treatment
- day lengthe0
- Outcome
- Plant heighte0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plant height generally increased as the day length increased in essential oil cultivars”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Fiber/grain cultivar height was unaffected by day length.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- fiber/grain cultivarse1
- Treatment
- day lengthe1
- Outcome
- Plant heighte1
- Direction
- not affectede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but was not affected in fiber/grain cultivars”
e1“Plant height generally increased as the day length increased in essential oil cultivars but was not affected in fiber/grain cultivars”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Civil twilight near 2 μmol·m −2 ·s −1 regulated hemp flowering.
- Taxon
- hempCannabis sativa subsp. sativae0
- Treatment
- civil twilighte0
- Outcome
- hemp floweringe0
- Value
- ~2 μmol·m −2 ·s −1e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“civil twilight of ~2 μmol·m −2 ·s −1 was discovered to be biologically effective in regulating hemp flowering”
Claim · model-written summary
Most essential oil cultivars tested had suitable photoperiods for tropical and subtropical cultivation.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- essential oil cultivarse0
- Outcome
- suitable photoperiods for tropical and sub-tropical region cultivatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“most of the essential oil cultivars and some southern fiber/grain cultivars tested express suitable photoperiods for tropical and sub-tropical region cultivation”
t0“hemp (Cannabis sativa L.)”
Claim · model-written summary
Some southern fiber/grain cultivars tested had suitable photoperiods for tropical and subtropical cultivation.
- Taxon
- hempCannabis sativa subsp. sativat0
- Material
- southern fiber/grain cultivarse0
- Outcome
- suitable photoperiods for tropical and sub-tropical region cultivatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“some southern fiber/grain cultivars tested express suitable photoperiods for tropical and sub-tropical region cultivation”
t0“hemp (Cannabis sativa L.)”
The same questions in other papers
light · growth · Cannabis sativaPositive and negative results
1 paper in the same direction as this paper · 11 in the opposite direction
- positive
- positive
- positive
9 papers more in this group
See all 13 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.