Abstract
Ammannia auriculata Willd. (eared redstem) has become one of the most troublesome weeds in paddy rice in China. Resistance to bensulfuron-methyl (BSM) has spread extensively in this species. Greenhouse and field experiments were conducted to determine how the eared redstem biotype and density affect competition against rice. In the greenhouse experiment, five treatments were tested: a BSM-susceptible biotype at low density (58 plants m−2, SL), a BSM-susceptible biotype at high density (288 plants m−2, SH), a BSM-resistant biotype at low density (RL), a BSM-resistant biotype at high density (RH), and a control without eared redstem (CK). Eared redstem grew slowly until 15 days after sowing (DAS); however, growth accelerated after 20 DAS, and the eared redstem plants were taller than the rice from 55 DAS on. The SH and RH treatments were associated with greater intraspecific competition: eared redstem plants in the SH and RH treatments had fewer branches, fewer capsules, and less shoot dry weight per individual plant relative to the SL and RL treatments. The SH and RH treatments also caused greater reductions in the rice yield. The dry weight of rice at 141 DAS was reduced by 73% in the SL treatment, 98% in the SH treatment, 51% in the RL treatment, and 82% in the RH treatment, all relative to the CK. At 141 DAS, BSM-resistant plants were smaller than BSM-susceptible plants, suggesting a fitness cost of herbicide resistance in the absence of a herbicide. In the field study, eared redstem densities as low as 5 plants m−2 reduced the rice yield by 22%. A density of 50 eared redstem plants m−2 reduced the rice yield by 70%. Overall, these findings demonstrate that eared redstem is a highly aggressive weed species and threatens the rice yield even at a low density. However, the findings also demonstrate that BSM-resistant populations are less competitive. There is an urgent need to develop integrated management programs for this aggressive weed, which may include tactics to shift competitive dynamics in favor of rice. Additionally, this research provides the theoretical basis for the damage level, resistance risk evaluation, and management strategy of eared redstem in rice cropping systems.
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Claims 11
Claim · model-written summary
Eared redstem became taller than rice from 55 days after sowing.
- Taxon
- rice
Oryza sativae0 - Interactor
- eared redsteme0weed
- Outcome
- taller than the ricee0
- Direction
- tallere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“eared redstem plants were taller than the rice from 55 DAS on.”
Claim · model-written summary
High density susceptible and resistant redstem had fewer branches, capsules and less shoot dry weight per plant than low density redstem.
Verbatim
e0“eared redstem plants in the SH and RH treatments had fewer branches, fewer capsules, and less shoot dry weight per individual plant relative to the SL and RL treatments.”
Claim · model-written summary
High density redstem reduced rice yield more than low density redstem.
- Taxon
- riceOryza sativae0
- Treatment
- SH and RH treatmentse0
- Outcome
- rice yielde0
- Direction
- reductionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The SH and RH treatments also caused greater reductions in the rice yield.”
Claim · model-written summary
SL redstem reduced rice dry weight at 141 days by 73% versus CK.
- Taxon
- riceOryza sativae0
- Organ / stage
- 141 DASe0
- Treatment
- SL treatmente0
- Outcome
- dry weight of ricee0
- Direction
- reducede0
- Value
- 73%e0
- Comparator
- CKe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The dry weight of rice at 141 DAS was reduced by 73% in the SL treatment, 98% in the SH treatment, 51% in the RL treatment, and 82% in the RH treatment, all relative to the CK.”
Claim · model-written summary
SH redstem reduced rice dry weight at 141 days by 98% versus CK.
- Taxon
- riceOryza sativae0
- Treatment
- SH treatmente0
- Outcome
- dry weight of ricee0
- Direction
- reducede0
- Value
- 98%e0
- Comparator
- CKe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The dry weight of rice at 141 DAS was reduced by 73% in the SL treatment, 98% in the SH treatment, 51% in the RL treatment, and 82% in the RH treatment, all relative to the CK.”
Claim · model-written summary
RL redstem reduced rice dry weight at 141 days by 51% versus CK.
- Taxon
- riceOryza sativae0
- Treatment
- RL treatmente0
- Outcome
- dry weight of ricee0
- Direction
- reducede0
- Value
- 51%e0
- Comparator
- CKe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The dry weight of rice at 141 DAS was reduced by 73% in the SL treatment, 98% in the SH treatment, 51% in the RL treatment, and 82% in the RH treatment, all relative to the CK.”
Claim · model-written summary
RH redstem reduced rice dry weight at 141 days by 82% versus CK.
- Taxon
- riceOryza sativae0
- Treatment
- RH treatmente0
- Outcome
- dry weight of ricee0
- Direction
- reducede0
- Value
- 82%e0
- Comparator
- CKe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The dry weight of rice at 141 DAS was reduced by 73% in the SL treatment, 98% in the SH treatment, 51% in the RL treatment, and 82% in the RH treatment, all relative to the CK.”
Claim · model-written summary
Resistant redstem plants were smaller than susceptible plants at 141 days.
Verbatim
e0“At 141 DAS, BSM-resistant plants were smaller than BSM-susceptible plants”
Claim · model-written summary
Five eared redstem plants per square metre reduced rice yield by 22% in the field.
- Taxon
- riceOryza sativae0
- Treatment
- eared redstem densities as low as 5 plants m−2e0
- Interactor
- eared redsteme0weed
- Outcome
- rice yielde0
- Direction
- reducede0
- Value
- 22%e0
- Setting
- field studye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the field study, eared redstem densities as low as 5 plants m−2 reduced the rice yield by 22%.”
Claim · model-written summary
Fifty eared redstem plants per square metre reduced rice yield by 70% in the field.
- Taxon
- riceOryza sativae0
- Treatment
- 50 eared redstem plants m−2e0
- Interactor
- eared redsteme0weed
- Outcome
- rice yielde0
- Direction
- reducede0
- Value
- 70%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“A density of 50 eared redstem plants m−2 reduced the rice yield by 70%.”
Claim · model-written summary
The authors call for integrated management of eared redstem.
- Taxon
- riceOryza sativae0
- Interactor
- weede0weed
- Outcome
- integrated management programse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There is an urgent need to develop integrated management programs for this aggressive weed, which may include tactics to shift competitive dynamics in favor of rice.”
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