Abstract
Plant competitive interactions influence the effect of herbicides, and the effect of competitive interactions on plant responses may be important to include in the ecological risk assessment of herbicides. In the present study the effect of competitive interactions and sublethal doses of 2 herbicides on plant species was investigated in competition experiments and fitted to empirical competition models. Two nontarget species commonly found in agroecosystems (Centaurea cyanus L. and Silene noctiflora L.) and 2 herbicides (glyphosate and metsulfuron methyl) were used in separate experiments. Plants were sprayed at the 6- to 8-leaf stage. Effects of herbicide treatments and plant density were modeled by generalization of a discrete hyperbolic competition model. The 10% effective dose (ED10) was calculated for C. cyanus. All experiments showed that as density increased, plants were negatively affected. Furthermore, in all cases, C. cyanus remained a better competitor than S. noctiflora. Nevertheless, the density of S. noctiflora (competitor) was an influential element in determining the ED10 of C. cyanus measured at the mature stage. With herbicide exposure, the competitive interactions were further altered; C. cyanus was less affected by glyphosate when S. noctiflora increased to high density. In contrast, at the young stage, conspecific density was important in determining the sensitivity of C. cyanus to metsulfuron methyl, whereas the density of the competitor S. noctiflora had a limited influence. Overall, the results demonstrate the importance of integrating the effect of herbicide and species interactions measured at the reproductive stage into the ecological risk assessments of pesticides. Environ Toxicol Chem 2019;38:2053-2064. © 2019 SETAC.
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Claims 7
Claim · model-written summary
Increasing density negatively affected Centaurea cyanus L..
- Taxon
- Centaurea cyanus L.
Centaurea cyanust0 - Treatment
- densitye0
- Outcome
- plants were negatively affectede0
- Direction
- negatively affectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Centaurea cyanus L. and Silene noctiflora L.”
e0“All experiments showed that as density increased, plants were negatively affected.”
Claim · model-written summary
Increasing density negatively affected Silene noctiflora L..
- Taxon
- Silene noctiflora L.
Silene noctiflorat0 - Treatment
- densitye0
- Outcome
- plants were negatively affectede0
- Direction
- negatively affectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Centaurea cyanus L. and Silene noctiflora L.”
e0“All experiments showed that as density increased, plants were negatively affected.”
Claim · model-written summary
C. cyanus was consistently the stronger competitor.
- Taxon
- Centaurea cyanus L.Centaurea cyanust0
- Outcome
- better competitore0
- Direction
- bettere0
- Comparator
- S. noctiflorae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Centaurea cyanus L. and Silene noctiflora L.”
e0“in all cases, C. cyanus remained a better competitor than S. noctiflora.”
Claim · model-written summary
Competitor S. noctiflora density influenced mature-stage C. cyanus ED10.
- Taxon
- Centaurea cyanus L.Centaurea cyanust0
- Organ / stage
- mature stagee0
- Interactor
- S. noctifloraSilene noctiflorae0other
- Outcome
- ED10 of C. cyanuse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Centaurea cyanus L. and Silene noctiflora L.”
e0“the density of S. noctiflora (competitor) was an influential element in determining the ED10 of C. cyanus measured at the mature stage.”
Claim · model-written summary
At high S. noctiflora density, glyphosate affected C. cyanus less.
- Taxon
- Centaurea cyanus L.Centaurea cyanust0
- Treatment
- glyphosatee0
- Interactor
- S. noctifloraSilene noctiflorae0other
- Outcome
- C. cyanus was less affectede0
- Direction
- less affectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Centaurea cyanus L. and Silene noctiflora L.”
e0“C. cyanus was less affected by glyphosate when S. noctiflora increased to high density.”
Claim · model-written summary
At the young stage, conspecific density determined C. cyanus sensitivity to metsulfuron methyl.
- Taxon
- Centaurea cyanus L.Centaurea cyanust0
- Organ / stage
- young stagee0
- Treatment
- metsulfuron methyle0
- Outcome
- sensitivity of C. cyanuse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Centaurea cyanus L. and Silene noctiflora L.”
e0“at the young stage, conspecific density was important in determining the sensitivity of C. cyanus to metsulfuron methyl”
Claim · model-written summary
At the young stage, S. noctiflora density had limited influence on C. cyanus sensitivity to metsulfuron methyl.
- Taxon
- Centaurea cyanus L.Centaurea cyanust0
- Interactor
- S. noctifloraSilene noctiflorae0other
- Outcome
- limited influencee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Centaurea cyanus L. and Silene noctiflora L.”
e0“the density of the competitor S. noctiflora had a limited influence.”