Abstract
We examined the aging of leaves prior to abscission and the consequences for estimating whole-crown primary production in Cannabis sativa L. (hemp). Leaves at three vertical positions in hemp crowns were examined from initial full leaf expansion until 42 days later. Photosynthetic capacity decreased as leaves aged regardless of crown position, light intensity, or photoperiod. Although leaves remained green, the photosynthetic capacity declined logarithmically to values of 50% and 25% of the maximum 9 and 25 days later, respectively. Plants grown under +450 μmol m−2 s−1 supplemental photosynthetically active radiation or enriched diffuse light responded similarly; there was no evidence that photoperiod or enriched diffuse light modified the gas exchange pattern. At approximately 14 days after full leaf expansion, leaf light levels >500 μmol m−2 s−1 decreased photosynthesis, which resulted in ≥10% lower maximum electron transport rate at ≥ 20 days of growth period. Furthermore, leaves were saturated at lower light levels as leaf age progressed (≤500 μmol m−2 s−1). Incorporating leaf age corrections of photosynthetic physiology is needed when estimating hemp primary production.
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Claims 7
Claim · model-written summary
Photosynthetic capacity of hemp leaves decreased as leaves aged, regardless of crown position, light intensity or photoperiod
- Taxon
- Cannabis sativa L.
Cannabis sativae1 - Organ / stage
- leavese2
- Outcome
- Photosynthetic capacitye2
- Direction
- decreasede2
- Qualifier
- regardless of crown position, light intensity, or photoperiode2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Cannabis sativa L. (hemp)”
e2“Photosynthetic capacity decreased as leaves aged regardless of crown position, light intensity, or photoperiod”
Claim · model-written summary
Photosynthetic capacity declined logarithmically to 50% of the maximum about 9 days after full leaf expansion
- Taxon
- Cannabis sativa L.Cannabis sativae1
- Outcome
- photosynthetic capacitye2
- Direction
- declinede2
- Value
- 50%e2
- Qualifier
- of the maximum 9 and 25 days later, respectivelye2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Cannabis sativa L. (hemp)”
e2“the photosynthetic capacity declined logarithmically to values of 50% and 25% of the maximum 9 and 25 days later, respectively”
Claim · model-written summary
Photosynthetic capacity declined logarithmically to 25% of the maximum 25 days later
- Taxon
- Cannabis sativa L.Cannabis sativae1
- Outcome
- photosynthetic capacitye2
- Direction
- declinede2
- Value
- 25%e2
- Qualifier
- 25 days latere2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Cannabis sativa L. (hemp)”
e2“the photosynthetic capacity declined logarithmically to values of 50% and 25% of the maximum 9 and 25 days later, respectively”
Claim · model-written summary
Photoperiod and enriched diffuse light did not modify the gas exchange pattern of hemp
- Taxon
- Cannabis sativa L.Cannabis sativae1
- Treatment
- photoperiod or enriched diffuse lighte2
- Outcome
- gas exchange patterne2
- Direction
- no_changeinferrede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Cannabis sativa L. (hemp)”
e2“there was no evidence that photoperiod or enriched diffuse light modified the gas exchange pattern”
Claim · model-written summary
Leaf light levels above 500 μmol m−2 s−1 decreased photosynthesis about 14 days after full leaf expansion
- Taxon
- Cannabis sativa L.Cannabis sativae1
- Treatment
- leaf light levels >500 μmol m−2 s−1e2
- Outcome
- photosynthesise2
- Direction
- decreasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Cannabis sativa L. (hemp)”
e2“At approximately 14 days after full leaf expansion, leaf light levels >500 μmol m−2 s−1 decreased photosynthesis”
Claim · model-written summary
Leaf light levels above 500 μmol m−2 s−1 gave a 10% or greater lower maximum electron transport rate after 20 days of growth
- Taxon
- Cannabis sativa L.Cannabis sativae1
- Treatment
- leaf light levels >500 μmol m−2 s−1e2
- Outcome
- maximum electron transport ratee3
- Direction
- lowere3
- Value
- ≥10%e3
- Qualifier
- at ≥ 20 days of growth periode3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Cannabis sativa L. (hemp)”
e2“At approximately 14 days after full leaf expansion, leaf light levels >500 μmol m−2 s−1 decreased photosynthesis”
e3“which resulted in ≥10% lower maximum electron transport rate at ≥ 20 days of growth period”
Claim · model-written summary
Leaves saturated at lower light levels as leaf age progressed
- Taxon
- Cannabis sativa L.Cannabis sativae1
- Organ / stage
- leavese2
- Outcome
- leaves were saturatede2
- Direction
- lowere2
- Value
- ≤500 μmol m−2 s−1e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Cannabis sativa L. (hemp)”
e2“leaves were saturated at lower light levels as leaf age progressed (≤500 μmol m−2 s−1)”
The same questions in other papers
light · physiology: gas exchange · Cannabis sativaPositive and negative results
1 in the opposite direction
- positive
light · physiology: photosynthesis · Cannabis sativaPositive and negative results
5 in the opposite direction
- positive
- positive
- positive
2 papers more in this group
See all 6 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.