Abstract
Growth room studies were conducted to determine the physiological basis of reduced glyphosate efficacy under low soil nitrogen using velvetleaf, common ragweed, and common lambsquarters as model species. Glyphosate dose–response experiments of weeds grown under low (1.5 mM) and high (15 mM) soil N were conducted. Velvetleaf and common lambsquarters grown under low N required 169 g ae ha−1 glyphosate for a significant reduction in biomass, but only 84 g ae ha−1 were required when grown under high N. However, when common ragweed was grown under low or high soil N there was no significant difference in response to glyphosate at all doses tested. The reduced glyphosate efficacy on velvetleaf and common lambsquarters under low N was primarily due to decreased herbicide translocation to the meristem. It appears that low N may decrease the net assimilation of carbon in plants, resulting in a decrease in the net export of sugars and hence glyphosate from mature leaves. Understanding the relationship between soil N and herbicide efficacy may help explain observed weed control failures with glyphosate and may contribute to our knowledge of the occurrence of weed patchiness in fields. This is the first report illustrating a physiological basis for decreased glyphosate efficacy under low soil N in selected weed species.
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Claims 7
Claim · model-written summary
Low-N velvetleaf required 169 g ae ha−1 glyphosate for significant biomass reduction, versus 84 g ae ha−1 under high N.
- Taxon
- Velvetleaf
Abutilon theophrastie0 - Treatment
- low Ne0
- Outcome
- reduction in biomasse0
- Direction
- requirede0
- Value
- 169 g ae ha−1e0
- Qualifier
- 84 g ae ha−1e0
- Comparator
- high Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Velvetleaf and common lambsquarters grown under low N required 169 g ae ha−1 glyphosate for a significant reduction in biomass, but only 84 g ae ha−1 were required when grown under high N.”
Claim · model-written summary
Low-N common lambsquarters required 169 g ae ha−1 glyphosate for significant biomass reduction, versus 84 g ae ha−1 under high N.
- Taxon
- common lambsquarters
Chenopodium albume0 - Treatment
- low Ne0
- Outcome
- reduction in biomasse0
- Direction
- requirede0
- Value
- 169 g ae ha−1e0
- Qualifier
- 84 g ae ha−1e0
- Comparator
- high Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Velvetleaf and common lambsquarters grown under low N required 169 g ae ha−1 glyphosate for a significant reduction in biomass, but only 84 g ae ha−1 were required when grown under high N.”
Claim · model-written summary
Common ragweed showed no significant difference in glyphosate response between low and high soil N at tested doses.
- Taxon
- common ragweed
Ambrosia artemisiifoliae0 - Treatment
- lowe0
- Outcome
- response to glyphosatee0
- Direction
- no significant differencee0
- Qualifier
- at all doses testede0
- Comparator
- high soil Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“when common ragweed was grown under low or high soil N there was no significant difference in response to glyphosate at all doses tested”
Claim · model-written summary
Reduced glyphosate efficacy in low-N velvetleaf was mainly attributed to reduced translocation to the meristem.
- Taxon
- velvetleafAbutilon theophrastie0
- Outcome
- reduced glyphosate efficacye0
- Qualifier
- decreased herbicide translocation to the meristeme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reduced glyphosate efficacy on velvetleaf and common lambsquarters under low N was primarily due to decreased herbicide translocation to the meristem”
Claim · model-written summary
Reduced glyphosate efficacy in low-N common lambsquarters was mainly attributed to reduced translocation to the meristem.
- Taxon
- common lambsquartersChenopodium albume0
- Outcome
- reduced glyphosate efficacye0
- Qualifier
- decreased herbicide translocation to the meristeme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reduced glyphosate efficacy on velvetleaf and common lambsquarters under low N was primarily due to decreased herbicide translocation to the meristem”
Claim · model-written summary
The authors propose that low N reduces net carbon assimilation.
- Taxon
- plantsViridiplantaee0
- Treatment
- low Ne0
- Outcome
- net assimilation of carbone0
Verbatim
e0“low N may decrease the net assimilation of carbon in plants”
Claim · model-written summary
The authors propose that reduced carbon assimilation decreases net sugar export and hence glyphosate export from mature leaves.
- Outcome
- net export of sugars and hence glyphosate from mature leavese0
- Qualifier
- resulting in a decreasee0
Not reportedTaxon
Verbatim
e0“resulting in a decrease in the net export of sugars and hence glyphosate from mature leaves”
The same questions in other papers
nitrogen · growth · Chenopodium album (common lambsquarters)Positive and negative results
1 paper in the same direction as this paper · 8 in the opposite direction
- positive
- positive
- positive
6 papers more in this group
See all 10 papers →nitrogen · growth · Abutilon theophrasti (velvetleaf)Results agree
3 papers in the same direction as this paper
- negative
- negative
- negative
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.