Abstract
Soybean cyst nematode (SCN; Heterodera glycines Ichinohe) is a major pathogen of soybean [Glycine max (L.) Merr.] in the United States. The spatial distribution of SCN in 10 naturally infested research sites in North Dakota was examined between 2006 and 2009. Egg densities were measured in plots and expressed as arithmetic means or grouped into classes using two categorical scales based on the effect of SCN on yield. Data were used to determine spatial distribution, egg cluster sizes, minimum plot sizes, and replications in field experiments. SCN populations varied among plots from undetected to 25,800 eggs/100 cm 3 of soil, and differences between adjacent plots were as high as sixfold. Mean to median ratios and Lloyd’s index of patchiness suggested an aggregated distribution in nine of the 10 sites. SCN cluster sizes varied in five of the 10 sites and optimum plot size over all sites varied depending on calculation methods. The minimum number of replications needed to detect specific differences among plots varied between field sites. Grouping data into either of the two categories generally increased the ability to detect differences between plots. The spatial distribution of SCN can be a critical factor affecting design and outcomes of field experiments.
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Claims 7
Claim · model-written summary
SCN egg populations ranged from undetected to 25,800 eggs per soil volume.
- Taxon
- Soybean
Glycine maxt0 - Interactor
- SCNe0pathogen
- Outcome
- SCN populationse0
- Value
- 25,800 eggs/100 cm 3 of soile0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“SCN populations varied among plots from undetected to 25,800 eggs/100 cm 3 of soil”
t0“Soybean”
Claim · model-written summary
Adjacent plots differed in SCN egg populations by as much as sixfold.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- differences between adjacent plotse0
- Value
- sixfolde0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“differences between adjacent plots were as high as sixfold”
Claim · model-written summary
SCN distribution was aggregated at nine of ten sites.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- aggregated distributione0
- Value
- nine of the 10 sitese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“an aggregated distribution in nine of the 10 sites”
Claim · model-written summary
SCN cluster sizes varied across five of ten sites.
- Taxon
- SoybeanGlycine maxt0
- Interactor
- SCNe0pathogen
- Outcome
- SCN cluster sizese0
- Direction
- variede0
- Value
- five of the 10 sitese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“SCN cluster sizes varied in five of the 10 sites”
Claim · model-written summary
Optimal plot size varied by calculation method.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- optimum plot sizee0
- Direction
- variede0
- Comparator
- calculation methodse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“optimum plot size over all sites varied depending on calculation methods”
Claim · model-written summary
Required replication count varied between field sites.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- minimum number of replicationse0
- Direction
- variede0
- Comparator
- field sitese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“The minimum number of replications needed to detect specific differences among plots varied between field sites”
Claim · model-written summary
Categorical grouping improved detection of differences between plots.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- ability to detect differences between plotse0
- Direction
- increasede0
- Comparator
- either of the two categoriese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Soybean”
e0“Grouping data into either of the two categories generally increased the ability to detect differences between plots”