Abstract
The widespread occurrence of herbicide-resistant (HR) Kochia scoparia is an increasing concern for growers in the US Great Plains and Canada. K. scoparia populations resistant to dicamba have been reported in six US states. Populations cross-resistant to dicamba and fluroxypyr have been reported from wheat fields in Montana, USA. It is unclear whether resistance to the auxinic herbicides (dicamba and/or fluroxypyr), can alter the fitness traits of K. scoparia. The objectives of this research were to compare the germination dynamics in response to thermal environment, vegetative growth and fecundity characteristics, and the relative competitive ability of dicamba-fluroxypyr-susceptible (S) vs.-resistant (R) K. scoparia selected from within a single segregating population (collected from wheat-fallow field in MT). S and R selected lines were developed after three generations of recurrent group selection. Compared to the S selected line, the R selected line had lower cumulative germination at all constant temperatures except 25°C, and at all alternating temperatures except 30/35°C. Also, the R selected line had delayed germination relative to the S selected line. The R had lower plant height, plant width, primary branches, total leaf area, stem diameter, and shoot dry weight compared with the S plants in the absence of competition. The reduction in seed production per plant resulted in a 39% fitness cost. The 1000-seed weight of R (1.6 g) was also less than that of S (2.6 g). When grown in an intraspecific competition at different mixture proportions, replacement series indices for the growth parameters further indicated that the R was less competitive than the S. Evident from this research, the dicamba-fluroxypyr-resistant R selected line is less likely to persist in a field population in the absence of the auxinic herbicides.
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Claims 9
Claim · model-written summary
The R selected line had lower cumulative germination than the S line at constant temperatures except 25°C.
- Taxon
- Kochia scoparia
Bassia scopariat0 - Material
- R selected linee1
- Treatment
- constant temperaturese1
- Outcome
- cumulative germinatione1
- Direction
- lowere1
- Qualifier
- except 25°Ce1
- Comparator
- S selected linee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Compared to the S selected line, the R selected line had lower cumulative germination at all constant temperatures except 25°C, and at all alternating temperatures except 30/35°C”
t0“Kochia scoparia”
Claim · model-written summary
The R selected line had lower cumulative germination than the S line at alternating temperatures except 30/35°C.
- Taxon
- Kochia scopariaBassia scopariat0
- Material
- R selected linee1
- Treatment
- alternating temperaturese1
- Outcome
- cumulative germinatione1
- Direction
- lowere1
- Qualifier
- 30/35°Ce1
- Comparator
- S selected linee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Compared to the S selected line, the R selected line had lower cumulative germination at all constant temperatures except 25°C, and at all alternating temperatures except 30/35°C”
t0“Kochia scoparia”
Claim · model-written summary
The R selected line had delayed germination relative to the S selected line.
- Taxon
- Kochia scopariaBassia scopariat0
- Material
- R selected linee2
- Outcome
- germinatione2
- Direction
- delayede2
- Comparator
- S selected linee2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“Also, the R selected line had delayed germination relative to the S selected line”
t0“Kochia scoparia”
Claim · model-written summary
The R plants had lower plant height, plant width and primary branches than S plants in the absence of competition.
- Taxon
- Kochia scopariaBassia scopariat0
- Material
- Re3
- Outcome
- plant height, plant width, primary branchese3
- Direction
- lowere3
- Qualifier
- in the absence of competitione3
- Comparator
- S plantse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“The R had lower plant height, plant width, primary branches, total leaf area, stem diameter, and shoot dry weight compared with the S plants in the absence of competition”
t0“Kochia scoparia”
Claim · model-written summary
The R plants had lower total leaf area, stem diameter and shoot dry weight than S plants in the absence of competition.
- Taxon
- Kochia scopariaBassia scopariat0
- Material
- Re3
- Outcome
- total leaf area, stem diameter, and shoot dry weighte3
- Direction
- lowere3
- Qualifier
- in the absence of competitione3
- Comparator
- S plantse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“The R had lower plant height, plant width, primary branches, total leaf area, stem diameter, and shoot dry weight compared with the S plants in the absence of competition”
t0“Kochia scoparia”
Claim · model-written summary
Reduced seed production per plant in the R line resulted in a 39% fitness cost.
- Taxon
- Kochia scopariaBassia scopariat0
- Outcome
- fitness coste4
- Value
- 39%e4
- Qualifier
- reduction in seed production per plante4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“The reduction in seed production per plant resulted in a 39% fitness cost”
t0“Kochia scoparia”
Claim · model-written summary
The 1000-seed weight of the R line (1.6 g) was less than that of the S line (2.6 g).
- Taxon
- Kochia scopariaBassia scopariat0
- Material
- Re5
- Outcome
- 1000-seed weighte5
- Direction
- lesse5
- Value
- 1.6 ge5
- Qualifier
- 2.6 ge5
- Comparator
- Se5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“The 1000-seed weight of R (1.6 g) was also less than that of S (2.6 g)”
t0“Kochia scoparia”
Claim · model-written summary
In intraspecific competition at different mixture proportions, the R line was less competitive than the S line by replacement series indices for growth parameters.
- Taxon
- Kochia scopariaBassia scopariat0
- Material
- Re6
- Treatment
- intraspecific competition at different mixture proportionse6
- Outcome
- replacement series indices for the growth parameterse6
- Direction
- less competitivee6
- Comparator
- Se6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“When grown in an intraspecific competition at different mixture proportions, replacement series indices for the growth parameters further indicated that the R was less competitive than the S”
t0“Kochia scoparia”
Claim · model-written summary
The R selected line is less likely to persist in a field population without the auxinic herbicides (author inference).
- Taxon
- Kochia scopariaBassia scopariat0
- Material
- R selected linee7
- Treatment
- absence of the auxinic herbicidese7
- Outcome
- persist in a field populatione7
- Direction
- less likelye7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“Evident from this research, the dicamba-fluroxypyr-resistant R selected line is less likely to persist in a field population in the absence of the auxinic herbicides”
t0“Kochia scoparia”