Abstract
Abstract Experiments were conducted in 2002 and 2003 to determine the influence of soil thermal amplitude on common cocklebur emergence. Additionally, common cocklebur achenes were collected in fall of 2003 and of 2004 to assess changes in light and temperature requirements for germination over a 12-mo period under field conditions. Common cocklebur germination in response to the light environment and to constant and fluctuating temperatures were evaluated under controlled conditions following achene retrieval from the field. There was a linear inverse relationship between shade intensity and soil thermal amplitude, which explained 77% of the variability in emergence in the field over 2 yr. Emergence decreased as soil thermal amplitude declined, with 95% shading resulting in a 72 to 88% reduction in emergence. Neither red nor far-red light had much effect on germination, and burial did not induce a light requirement. Germination of achenes retrieved from the soil surface or buried in soil generally was not affected by red or far-red light, and the achenes did not acquire a red-light requirement following burial. Daily exposure to natural greenhouse light at 24 to 30 C was essential for germination immediately following achene maturation, whereas no germination occurred in darkness. A thermal fluctuation of 15 C increased germination percentages over those at constant temperatures regardless of time after maturation or retrieval-depth of achenes. The mean fluctuating temperature over all sample dates that was generally optimal for germination was 25 C (17.5/32.5 C low/high temperatures; 15 C daily fluctuation) in April or May and July or August in both years. Germination was generally optimum at constant temperatures of 35 or 40 C. The higher mean temperature requirement for germination at constant temperatures than at fluctuating temperatures likely contributes to reduced emergence in spring and summer months, when earlier emerging weed species or crops have already become established, and the thermal fluctuation requirement for germination reduces the likelihood of emergence in an environment where light availability is diminished. Nomenclature: Common cocklebur, Xanthium strumarium L. XANST
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 13
Claim · model-written summary
Shade intensity was inversely related to soil thermal amplitude and explained 77% of field emergence variation.
Not reportedDirection
Verbatim
e0“There was a linear inverse relationship between shade intensity and soil thermal amplitude, which explained 77% of the variability in emergence in the field over 2 yr”
t0“Common Cocklebur”
Claim · model-written summary
Cocklebur emergence decreased as soil thermal amplitude declined.
Verbatim
e0“Emergence decreased as soil thermal amplitude declined”
t0“Common Cocklebur”
Claim · model-written summary
95% shade reduced cocklebur emergence by 72 to 88%.
Not reportedComparator
Verbatim
e0“95% shading resulting in a 72 to 88% reduction in emergence”
t0“Common Cocklebur”
Claim · model-written summary
Red light had little effect on cocklebur germination.
Not reportedComparator
Verbatim
e0“Neither red nor far-red light had much effect on germination”
t0“Common Cocklebur”
Claim · model-written summary
Far-red light had little effect on cocklebur germination.
Not reportedComparator
Verbatim
e0“Neither red nor far-red light had much effect on germination”
t0“Common Cocklebur”
Claim · model-written summary
Burial did not induce a light requirement in cocklebur achenes.
Not reportedComparator
Verbatim
e0“burial did not induce a light requirement”
t0“Common Cocklebur”
Claim · model-written summary
Natural greenhouse light at 24 to 30 C was essential for germination just after achene maturation.
- Taxon
- Common Cockleburt0
- Organ / stage
- achene maturatione0
- Treatment
- Daily exposure to natural greenhouse light at 24 to 30 Ce0
- Outcome
- essential for germinatione0
Not reportedDirection
Verbatim
e0“Daily exposure to natural greenhouse light at 24 to 30 C was essential for germination immediately following achene maturation”
t0“Common Cocklebur”
Claim · model-written summary
No cocklebur germination occurred in darkness immediately after maturation.
Not reportedDirection
Verbatim
e0“no germination occurred in darkness”
t0“Common Cocklebur”
Claim · model-written summary
A 15 C thermal fluctuation increased germination over constant temperatures.
Verbatim
e0“A thermal fluctuation of 15 C increased germination percentages over those at constant temperatures regardless of time after maturation or retrieval-depth of achenes”
t0“Common Cocklebur”
Claim · model-written summary
A mean fluctuating temperature of 25 C was generally optimal for cocklebur germination.
Verbatim
e0“The mean fluctuating temperature over all sample dates that was generally optimal for germination was 25 C (17.5/32.5 C low/high temperatures; 15 C daily fluctuation) in April or May and July or August in both years”
t0“Common Cocklebur”
Claim · model-written summary
Constant temperatures of 35 or 40 C were generally optimal for germination.
Verbatim
e0“Germination was generally optimum at constant temperatures of 35 or 40 C”
t0“Common Cocklebur”
Claim · model-written summary
Higher mean temperature requirements under constant temperature likely reduce cocklebur emergence in spring and summer.
Verbatim
e0“The higher mean temperature requirement for germination at constant temperatures than at fluctuating temperatures likely contributes to reduced emergence in spring and summer months”
t0“Common Cocklebur”
Claim · model-written summary
The thermal fluctuation requirement for germination reduces the likelihood of cocklebur emergence where light is limited.
Verbatim
e0“the thermal fluctuation requirement for germination reduces the likelihood of emergence in an environment where light availability is diminished”
t0“Common Cocklebur”
The same questions in other papers
shade · growth · Xanthium strumarium (cocklebur)Positive and negative results
1 in the opposite direction
- positive
light · growth · Xanthium strumarium (cocklebur)Positive and negative results
2 papers in the same direction as this paper · 4 in the opposite direction
- negative
- positive
- positive
3 papers more in this group
See all 7 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.