Abstract
Abstract Accurate simulation of the impact of weeds on crops requires adequate quantification of weed effects on crop biomass and on the partitioning of crop biomass into grain. The first objective of this study was to determine whether radiation‐use efficiency (RUE) values of maize ( Zea mays L.) and johnsongrass [ Sorghum halepense (L.) Pers.] grown in monoculture could be applied to these species grown in mixed plantings. The second objective was to investigate how maize yield and harvest index (HI) respond to johnsongrass competition. Monoculture plots of maize and johnsongrass and plots with the two species competing were established on Houston black clay (fine, montmorillonitic, thermic Udic Pellustert) in the field at Temple, TX, in 1991 and 1992. Sequential measurements of light interception (IPAR) and of biomass were used to calculate values for RUE prior to anthesis. Yield and HI of maize were measured after physiological maturity. Johnsongrass reduced grain yield of maize by 5% in 1991 and by 33 to 49% in 1992. The greater competition in the second year also reduced maize HI from 0.55 in the first year to 0.43 in the second. Values of RUE of maize and johnsongrass growing together were similar to weighted means of monoculture RUE values. The weights were the relative fraction of each species in the mixture. The measured values of maize‐johnsongrass mixtures differed from weighted means by 3 to 11% in both years.
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Claims 5
Claim · model-written summary
Johnsongrass reduced maize grain yield by 5% in 1991.
- Treatment
- Johnsongrasse0
- Interactor
- Johnsongrass
.jpg?width=60)
Sorghum halepensee0weed - Outcome
- grain yield of maizee0
- Direction
- reducede0
- Value
- 5%e0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Johnsongrass reduced grain yield of maize by 5% in 1991”
Claim · model-written summary
Johnsongrass reduced maize grain yield by 33 to 49% in 1992.
- Treatment
- Johnsongrasse0
- Interactor
- JohnsongrassSorghum halepensee0weed
- Outcome
- grain yield of maizee0
- Direction
- reducede0
- Value
- 33 to 49%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Johnsongrass reduced grain yield of maize by 5% in 1991 and by 33 to 49% in 1992”
Claim · model-written summary
Greater competition reduced maize harvest index from 0.55 in the first year to 0.43 in the second.
- Treatment
- greater competitione0
- Outcome
- maize HIe0
- Direction
- reducede0
- Value
- 0.43e0
- Qualifier
- 0.55 in the first yeare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The greater competition in the second year also reduced maize HI from 0.55 in the first year to 0.43 in the second”
Claim · model-written summary
Radiation-use efficiency of maize and johnsongrass in mixtures resembled weighted means of monoculture values.
- Interactor
- johnsongrassSorghum halepensee0weed
- Outcome
- Values of RUE of maize and johnsongrass growing togethere0
- Direction
- similare0
- Comparator
- weighted means of monoculture RUE valuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Values of RUE of maize and johnsongrass growing together were similar to weighted means of monoculture RUE values”
Claim · model-written summary
Measured RUE values of maize–johnsongrass mixtures differed from weighted means by 3 to 11% in both years.
- Interactor
- johnsongrassSorghum halepensee0weed
- Outcome
- measured values of maize‐johnsongrass mixturese0
- Direction
- differede0
- Value
- 3 to 11%e0
- Comparator
- weighted meanse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The measured values of maize‐johnsongrass mixtures differed from weighted means by 3 to 11% in both years”
The same questions in other papers
Sorghum halepense · yield · Zea mays (maize)Positive and negative results
2 papers in the same direction as this paper · 3 in the opposite direction
- positive
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