Abstract
SUMMARY Crop canopy characteristics and management factors that affect the canopy structure can influence crop competitive ability against weeds. The goal of the current study was to understand the interaction between nitrogen (N) fertilizer rate and redroot pigweed ( Amaranthus retroflexus ) density on common bean ( Phaseolus vulgaris L.) canopy characteristics and N assimilation. Experiments were conducted to determine the growth responses of two bean genotypes with contrasting growth habits to different N fertilizer rates under no, low and high redroot pigweed pressure. Nitrogen was applied at rates of 0, 50, 100 and 200 kg/ha for a semi-erect variety and 0, 35, 70 and 140 kg/ha for an erect bean variety. Leaf area index (LAI), leaf area duration (LAD), leaf chlorophyll, N assimilation and N assimilation rate for both bean growth habits increased with N application rate at no and low weed density. The negative effect of redroot pigweed competition on LAI, LAD, N assimilation and N assimilation rate increased with redroot pigweed density, and with N application rate for the high weed density. Stepwise multiple regression analysis showed that N assimilation and chlorophyll concentration accounted for 0·73–0·87, overall, of the variation in yield loss due to weed competition. It is concluded that greater N assimilation in the semi-erect growth habit compared with the erect growth habit is the cause of its higher competitive ability against the weed, as it improves the effective canopy traits that confer potential for resource pre-emption.
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Claims 6
Claim · model-written summary
Nitrogen rate increased leaf area index and duration at no and low weed density.
- Taxon
- common bean
Phaseolus vulgarise1 - Treatment
- N application ratee0
- Interactor
- redroot pigweede1weed
- Outcome
- Leaf area index (LAI), leaf area duration (LAD)e0
- Direction
- increasede0
- Qualifier
- no and low weed densitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area index (LAI), leaf area duration (LAD), leaf chlorophyll, N assimilation and N assimilation rate for both bean growth habits increased with N application rate at no and low weed density”
e1“redroot pigweed ( Amaranthus retroflexus ) density on common bean ( Phaseolus vulgaris L.)”
Claim · model-written summary
Nitrogen rate increased leaf chlorophyll and N assimilation at no and low weed density.
- Taxon
- common beanPhaseolus vulgarise1
- Treatment
- N application ratee0
- Interactor
- redroot pigweede1weed
- Outcome
- leaf chlorophyll, N assimilation and N assimilation ratee0
- Direction
- increasede0
- Qualifier
- no and low weed densitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf area index (LAI), leaf area duration (LAD), leaf chlorophyll, N assimilation and N assimilation rate for both bean growth habits increased with N application rate at no and low weed density”
e1“redroot pigweed ( Amaranthus retroflexus ) density on common bean ( Phaseolus vulgaris L.)”
Claim · model-written summary
Pigweed density intensified negative effects on bean canopy and nitrogen assimilation.
- Taxon
- common beanPhaseolus vulgarise1
- Interactor
- redroot pigweede0weed
- Outcome
- negative effect of redroot pigweed competition on LAI, LAD, N assimilation and N assimilation ratee0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“negative effect of redroot pigweed competition on LAI, LAD, N assimilation and N assimilation rate increased with redroot pigweed density”
e1“common bean ( Phaseolus vulgaris L.)”
Claim · model-written summary
Higher nitrogen intensified pigweed competition effects at high weed density.
- Taxon
- common beanPhaseolus vulgarise1
- Treatment
- N application ratee0
- Interactor
- redroot pigweede0weed
- Outcome
- negative effect of redroot pigweed competitione0
- Direction
- increasede0
- Qualifier
- high weed densitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“negative effect of redroot pigweed competition on LAI, LAD, N assimilation and N assimilation rate increased with redroot pigweed density, and with N application rate for the high weed density”
e1“common bean ( Phaseolus vulgaris L.)”
Claim · model-written summary
N assimilation and chlorophyll explained 0·73–0·87 of yield loss variation from weed competition.
- Taxon
- common beanPhaseolus vulgarise1
- Interactor
- redroot pigweede2weed
- Outcome
- variation in yield loss due to weed competitione0
- Value
- 0·73–0·87e0
- Qualifier
- N assimilation and chlorophyll concentratione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N assimilation and chlorophyll concentration accounted for 0·73–0·87, overall, of the variation in yield loss due to weed competition”
e1“common bean ( Phaseolus vulgaris L.)”
e2“nitrogen (N) fertilizer rate and redroot pigweed”
Claim · model-written summary
Authors attributed semi-erect bean competitive ability to greater nitrogen assimilation and effective canopy traits.
- Taxon
- common beanPhaseolus vulgarise1
- Material
- semi-erect growth habite0
- Interactor
- redroot pigweede2weed
- Outcome
- competitive ability against the weede0
- Direction
- highere0
- Qualifier
- greater N assimilatione0
- Comparator
- erect growth habite0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“greater N assimilation in the semi-erect growth habit compared with the erect growth habit is the cause of its higher competitive ability against the weed, as it improves the effective canopy traits that confer potential for resource pre-emption”
e1“common bean ( Phaseolus vulgaris L.)”
e2“nitrogen (N) fertilizer rate and redroot pigweed”
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See all 60 papers →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.