Abstract
Productivity and persistence of white clover (Trifolium repens) in the southeastern United States are limited by a complex of pathogens and environmental stresses including peanut stunt virus (PSV), root-knot nematodes (Meloidogyne incognita), and drought. Determining the separate and combined effects of these factors has been hampered by the rapid natural spread of PSV to noninoculated plants. Half-sib white clover plants with and without hypersensitive resistance to PSV were used to overcome this problem. Effects of PSV, M. incognita, and drought on clover growth and persistence in the field were measured using a factorial arrangement of treatments in a split-plot design in which half of the plots were irrigated to eliminate drought stress. Data were collected in 2 consecutive years on dry weight herbage yield, stolon density, leaf area, petiole length, seed production, nematode population density, rainfall, and soil moisture. Virus infection reduced cumulative herbage yield 14% in the first year and 24% in the second year. In the first year, irrigation increased cumulative herbage yield 5 and 13% in the presence and absence of M. incognita, respectively, compared with nonirrigated control plots without M. incognita. Cumulative herbage yield in drought-stressed plots was reduced 9% in the presence of M. incognita compared with nonirrigated control plots without M. incognita. In the second year, cumulative herbage yield in the absence of M. incognita was 54% higher in irrigated plots than in nonirrigated plots, while yield in nonirrigated plots was 17% lower in the presence of M. incognita. Clover persistence, as measured by stolon density, was reduced by PSV, M. incognita, and drought, but no interactions occurred. Reductions in persistence were most severe in M. incognita treatments, resulting in nearly complete loss of stands by the end of the second year. Virus infection reduced leaf area and petiole length in all treatments, but reductions were proportionately greater in irrigated plots. Nematode infestation generally reduced leaf area and petiole length, but the effect was less than that of PSV. Mean seed yields from 100 seed heads per plot were lower in nematode-infested plots, but slightly higher in nonirrigated plots and PSV-treated plots. Drought stress, M. incognita, and PSV acted independently in reducing forage productivity and persistence.
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Claims 15
Claim · model-written summary
Virus infection reduced first-year herbage yield 14%.
- Taxon
- white clover (Trifolium repens)
Trifolium repenst0 - Treatment
- Virus infectione0
- Outcome
- cumulative herbage yielde0
- Direction
- reducede0
- Value
- 14%e0
- Qualifier
- first yeare0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Virus infection reduced cumulative herbage yield 14% in the first year”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Virus infection reduced second-year herbage yield 24%.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- Virus infectione0
- Outcome
- herbage yielde0
- Direction
- reducede0
- Value
- 24%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Virus infection reduced cumulative herbage yield 14% in the first year and 24% in the second year”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Irrigation increased first-year yield 5% with nematodes.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- irrigatione0
- Interactor
- M. incognita
_penetrates_a_tomato_root_-_USDA-ARS.jpg?width=60)
Meloidogyne incognitae0pathogen - Outcome
- cumulative herbage yielde0
- Direction
- increasede0
- Value
- 5e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_penetrates_a_tomato_root_-_USDA-ARS.jpg?width=500)
Verbatim
e0“irrigation increased cumulative herbage yield 5 and 13% in the presence and absence of M. incognita, respectively”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Irrigation increased first-year yield 13% without nematodes.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- irrigatione0
- Outcome
- cumulative herbage yielde0
- Direction
- increasede0
- Value
- 13%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“irrigation increased cumulative herbage yield 5 and 13% in the presence and absence of M. incognita, respectively”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Nematodes reduced drought-stressed herbage yield 9%.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- presence of M. incognitae0
- Interactor
- M. incognitaMeloidogyne incognitae0pathogen
- Outcome
- Cumulative herbage yielde0
- Direction
- reducede0
- Value
- 9%e0
- Comparator
- nonirrigated control plots without M. incognitae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cumulative herbage yield in drought-stressed plots was reduced 9% in the presence of M. incognita compared with nonirrigated control plots without M. incognita.”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Second-year irrigation increased herbage yield 54% without nematodes.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- irrigated plotse0
- Outcome
- cumulative herbage yielde0
- Direction
- highere0
- Value
- 54%e0
- Comparator
- nonirrigated plotse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“cumulative herbage yield in the absence of M. incognita was 54% higher in irrigated plots than in nonirrigated plots”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Nematodes lowered nonirrigated yield 17%.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- presence of M. incognitae0
- Interactor
- M. incognitaMeloidogyne incognitae0pathogen
- Outcome
- yielde0
- Direction
- lowere0
- Value
- 17%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“yield in nonirrigated plots was 17% lower in the presence of M. incognita”
t0“white clover (Trifolium repens)”
Claim · model-written summary
PSV reduced clover persistence.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- PSVe0
- Interactor
- PSVPeanut stunt viruse0pathogen
- Outcome
- Clover persistencee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Clover persistence, as measured by stolon density, was reduced by PSV, M. incognita, and drought”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Nematodes reduced clover persistence, nearly eliminating stands by year two.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- M. incognita treatmentse0
- Interactor
- M. incognitaMeloidogyne incognitae0pathogen
- Outcome
- persistencee0
- Direction
- Reductionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reductions in persistence were most severe in M. incognita treatments, resulting in nearly complete loss of stands by the end of the second year.”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Drought reduced clover persistence.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- droughte0
- Outcome
- Clover persistencee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Clover persistence, as measured by stolon density, was reduced by PSV, M. incognita, and drought”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Virus infection reduced leaf area and petiole length.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- Virus infectione0
- Outcome
- leaf area and petiole lengthe0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Virus infection reduced leaf area and petiole length in all treatments”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Nematode infestation generally reduced leaf area and petiole length.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- Nematode infestatione0
- Outcome
- leaf area and petiole lengthe0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nematode infestation generally reduced leaf area and petiole length”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Nematode infestation lowered mean seed yields.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- nematode-infested plotse0
- Outcome
- Mean seed yieldse0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mean seed yields from 100 seed heads per plot were lower in nematode-infested plots”
t0“white clover (Trifolium repens)”
Claim · model-written summary
Nonirrigated plots had slightly higher seed yields.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- nonirrigated plotse0
- Outcome
- seed yieldse0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mean seed yields from 100 seed heads per plot were lower in nematode-infested plots, but slightly higher in nonirrigated plots and PSV-treated plots.”
t0“white clover (Trifolium repens)”
Claim · model-written summary
PSV treated plots had slightly higher seed yields.
- Taxon
- white clover (Trifolium repens)Trifolium repenst0
- Treatment
- PSV-treated plotse0
- Outcome
- seed yieldse0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mean seed yields from 100 seed heads per plot were lower in nematode-infested plots, but slightly higher in nonirrigated plots and PSV-treated plots.”
t0“white clover (Trifolium repens)”
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See all 11 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.