Abstract
The impact of Meloidogyne hapla on alfalfa (Medicago sativa) yield was described by a multiple point damage model as a function of current plant status, cumulative pest stress, and crop history. Nematode-degree days (NDD(female symbol)), calculated on a physiologic time scale as total area under the adult female population density curve, were used to express M. hapla parasitism as cumulative nematode dosage. NDD(female symbol) increased exponentially over physiological time at rates relative to M. hapla initial population density of eggs and second-stage juveniles (Pi). Dosage accumulation rates, varying from 213 to 272 NDD(female symbol) per degree day, did not differ (P = 0.05) among six Pi levels. Cumulative yield reductions, increasing linearly with NDD(female symbol) over time to 50% of the M. hapla-free controls, were well correlated for the six initial Pi levels (r(2) = 0.93). Progressive reductions in alfalfa yields to 65% of the nematode-free controls, reflective of the prolonged exposure of the crop to M. hapla, were adequately described by NDD model estimates of either combined population densities of eggs and juveniles or adult females. Cumulative area under the combined eggs (e) and juvenile (J) population curve (NDD(e+J)) and NDD(female symbol) were linearly related (r(2) = 0.97).
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Claims 6
Claim · model-written summary
NDD(female symbol) increased exponentially over physiological time at rates relative to the initial M. hapla population density.
- Taxon
- alfalfa
Medicago sativae0 - Interactor
- M. hapla
Meloidogyne haplae1pest - Outcome
- NDD(female symbol)e1
- Direction
- increased exponentiallye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The impact of Meloidogyne hapla on alfalfa (Medicago sativa) yield was described by a multiple point damage model”
e1“NDD(female symbol) increased exponentially over physiological time at rates relative to M. hapla initial population density of eggs and second-stage juveniles (Pi)”
Claim · model-written summary
Dosage accumulation rates of 213 to 272 NDD(female symbol) per degree day did not differ among six initial population levels.
- Taxon
- alfalfaMedicago sativae0
- Outcome
- Dosage accumulation ratese2
- Direction
- did not differe2
- Value
- 213 to 272 NDD(female symbol) per degree daye2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The impact of Meloidogyne hapla on alfalfa (Medicago sativa) yield was described by a multiple point damage model”
e2“Dosage accumulation rates, varying from 213 to 272 NDD(female symbol) per degree day, did not differ (P = 0.05) among six Pi levels”
Claim · model-written summary
Cumulative yield reductions increased linearly with NDD to 50% of M. hapla-free controls and were well correlated for the six initial population levels.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- M. haplaMeloidogyne haplae3pest
- Outcome
- Cumulative yield reductionse3
- Direction
- increasing linearlye3
- Value
- 50%e3
- Qualifier
- well correlated for the six initial Pi levels (r(2) = 0.93)e3
- Comparator
- M. hapla-free controlse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The impact of Meloidogyne hapla on alfalfa (Medicago sativa) yield was described by a multiple point damage model”
e3“Cumulative yield reductions, increasing linearly with NDD(female symbol) over time to 50% of the M. hapla-free controls, were well correlated for the six initial Pi levels (r(2) = 0.93)”
Claim · model-written summary
Alfalfa yields were reduced to 65% of nematode-free controls under prolonged exposure to M. hapla.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- prolonged exposure of the crop to M. haplae4
- Interactor
- M. haplaMeloidogyne haplae4pest
- Outcome
- alfalfa yieldse4
- Direction
- Progressive reductionse4
- Value
- 65%e4
- Comparator
- nematode-free controlse4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The impact of Meloidogyne hapla on alfalfa (Medicago sativa) yield was described by a multiple point damage model”
e4“Progressive reductions in alfalfa yields to 65% of the nematode-free controls, reflective of the prolonged exposure of the crop to M. hapla, were adequately described by NDD model estimates of either combined population densities of eggs and juveniles or adult females”
Claim · model-written summary
Alfalfa yield reductions were adequately described by NDD model estimates of eggs and juveniles or of adult females.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- M. haplaMeloidogyne haplae4pest
- Outcome
- NDD model estimatese4
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The impact of Meloidogyne hapla on alfalfa (Medicago sativa) yield was described by a multiple point damage model”
e4“Progressive reductions in alfalfa yields to 65% of the nematode-free controls, reflective of the prolonged exposure of the crop to M. hapla, were adequately described by NDD model estimates of either combined population densities of eggs and juveniles or adult females”
Claim · model-written summary
NDD(female symbol) and NDD(e+J) were linearly related, r(2) = 0.97.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- Meloidogyne haplaMeloidogyne haplae0pest
- Outcome
- NDD(female symbol)e5
- Qualifier
- r(2) = 0.97e5
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The impact of Meloidogyne hapla on alfalfa (Medicago sativa) yield was described by a multiple point damage model”
e5“Cumulative area under the combined eggs (e) and juvenile (J) population curve (NDD(e+J)) and NDD(female symbol) were linearly related (r(2) = 0.97)”
The same questions in other papers
Meloidogyne hapla · yield · Medicago sativa (alfalfa)Results agree
1 paper in the same direction as this paper
- negative
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.