The Determination of Normalizing Transformations for Nematode Count Data From Soil Samples and of Efficient Sampling Schemes

Marks, C. F.; Proctor, Jean R.

doi:10.1163/187529274x00023

Cited by 41 publications

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“…Count data were transformed by ln(x + c), where x is nematodes/kg soil and roots sampled, and c is constant. The value of c was optimised for each experiment using chi-squared principles to normalise the data (Proctor and Marks 1974;Berry 1987). Analysis of variance was performed using GENSTAT 6.1 (Payne et al 2002) and mean squares were used to estimate heritability of P. thornei resistance in the ITMI population (Hartl et al 1988).…”

Section: Phenotypic Assessment Of P Thornei Resistancementioning

confidence: 99%

Mapping quantitative trait loci for resistance to Pratylenchus thornei from synthetic hexaploid wheat in the International Triticeae Mapping Initiative (ITMI) population

Zwart¹,

Thompson²,

Sheedy³

et al. 2006

Aust. J. Agric. Res.

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Abstract. Root-lesion nematode (Pratylenchus thornei) is a serious pathogen of wheat in many countries. The International Triticeae Mapping Initiative (ITMI) population of recombinant inbred lines (RILs) was assessed for resistance to P. thornei to determine the chromosome locations of the resistance genes. The ITMI population is derived from a cross between the resistant synthetic hexaploid wheat W-7984 and a susceptible bread wheat cultivar Opata 85. Two years of phenotypic data for resistance to P. thornei were obtained in replicated glasshouse trials. Quantitative trait locus (QTL) analysis was performed using available segregation and map data for 114 RILs. A QTL on chromosome 6DS showed consistent effects for reduced nematode numbers (partial resistance) across years and accounted for 11% and 23% of the phenotypic variation. A second QTL for P. thornei resistance on chromosome 2BS accounted for an additional 19% and 5%. Restriction fragment length polymorphism (RFLP) and simple sequence repeat (SSR) markers associated with the QTLs are physically located in regions rich in major genes at the distal ends of the short chromosome arms of 6D and 2B. SSR markers with potential for marker-assisted selection of P. thornei resistance effective in different genetic backgrounds have been identified.

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Section: Phenotypic Assessment Of P Thornei Resistancementioning

confidence: 99%

Mapping quantitative trait loci for resistance to Pratylenchus thornei from synthetic hexaploid wheat in the International Triticeae Mapping Initiative (ITMI) population

Zwart¹,

Thompson²,

Sheedy³

et al. 2006

Aust. J. Agric. Res.

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“…Another difficulty is that détermina-tion of nematode counts is imprécise. Based on calculations by Proctor and Marks (1974) in Ontario, the sampling schemes used for diagnostic samples in the Maritime provinces provide estimâtes only to within about 50% of the true population mean. More data at various locations with différent soil and weather conditions, with other potato cultivars or différent crop rotations, with more précise knowledge of winter survival of nematodes, and improved sampling schemes, should provide better estimâtes of nematode density.…”

Section: Nematode Advisory Servicesmentioning

confidence: 99%

Plant parasitic nematodes and their management in the Maritime provinces of Canada

Kimpinski

Thompson

2005

phyto

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Cet article présente une revue des nematodes phytoparasites qui causent des problèmes au Nouveau-Brunswick, en Nouvelle-Ecosse et à l'île-du Prince-Édouard, ainsi que les approches de lutte utilisées. Le nématode des lésions des racines (Pratylenchus penetrans) est la seule espèce de nématode de la région qui provoque régulièrement des baisses de rendement. Le nématode des nodosités des racines (Meloidogyne hapla) cause occasionnellement des dommages aux carottes (Daucus carota) mais les niveaux de population de ce nématode sont généralement très faibles. Le nématode du kyste du trèfle (Heterodera trifolii) est répandu mais il n'a pas causé de dommages aux récoltes de la région. Les techniques de production utilisées afin de réduire l'impact des nematodes phytoparasites dans les Maritimes, à savoir la rotation des cultures, les traitements nématicides, le renforcement des règlements de quarantaine et les pratiques de labourage, sont discutées. Un service-conseil sur les nematodes est également considéré.This paper presents a review of the plant parasitic nematodes that are of concern in New Brunswick, Nova Scotia, and Prince-Edward-Island, and the approaches used to manage them. The root lesion nematode (Pratylenchus penetrans) is the only nematode species in the region that regularly reduces crop yields. The northern root-knot nematode (Meloidogyne hapla) occasionally causes damage to carrots (Daucus carota), but population levels of this nematode species usually are very low. The clover cyst nematode (Heterodera trifolii) is widespread, but has not caused any damage to crops in the region. Management procedures used to reduce the impact of plant parasitic nematodes in the Maritime provinces, e.g. crop rotations, nematicide treatments, enforcement of quarantine regulations, and tillage practices are discussed. A nematode advisory service is also considered

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“…and Marks (1974) tested the use of transformations for "normalizing" count data and also investigated the intensity of sampling of field populations of nematodes. While determining that a log (x + c) transformation was an acceptable normalizing transformation, these authors also found that in practical sampling, a set of five samples, each consisting of 40 soil cores, was required to estimate the population of lesion nematodes in a 0.01-ha plot, with a precision level such that 95% of the estimates of nematode density were within 20% of the true mean for the plot.…”

Section: Knowledge Of Distributionmentioning

confidence: 99%

“…The sampling to achieve this level of precision would require 7 h per 0.01-ha plot; hence, our earlier comment about the realism of sampling at finer scales. Proctor and Marks (1974) acknowledged that "The distribution of nematode counts is likely to change not only with sampling method and type of nematode but with plot size, soil type, and types of crop. "…”

Section: Knowledge Of Distributionmentioning

confidence: 99%

Nematode biodiversity in Canadian agricultural soils

Potter¹,

McKeown²

2003

Can. J. Soil. Sci.

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The biodiversity of soil-inhabiting nematodes in Canada is incompletely known, as large areas of Canada’s landmass have not been surveyed for nematode fauna. Nematodes considered as indigenous are generally well adapted to a variety of ecological niches and climatic zones. Much of the available information is based on agricultural ecosystems and agricultural species, and thus is biased toward conditions in disturbed ecosystems and away from “primeval” ecology. Introduced nematode species are frequently quite pathogenic, even to exotic host plants from the same geographic point of origin. Estimates of crop loss due to single species infestations of pathogenic nematodes and the costs of nematode control using chemicals are reasonably well known, averaging about 10% of crop value, but ranging to 100% depending on the situation; the cost of damage by multiple-species infestations is less defined. Nematode-suppressive mechanisms are understood in only a few plant species; sulfur appears to be important as a constituent of active compounds in suppressive plants of agricultural origin. Similarly, some native plants are equally adapted with allelopathic chemicals that suppress nematodes. Management of nematode populations in agricultural soils by integrated crop management methods is at an early stage, requiring research to quantify effects of nematode-suppressive plants and soil amendments containing nitrogen. An integrated program could include nematode-suppressive plants, appropriate soil amendments, and the promotion of microbial antagonists. Different mathematical methods may be required to analyze and explain multi-factor nematode control systems. Less-toxic management systems could benefit the soil-inhabiting nematodes that predate arthropod soil pests. Further research on soil-borne nematodes may demonstrate the value of nematodes as indicators of agroecosystem health and environmental pollutants. Key words: Biocontrol, biodiversity, nematode distribution, nematode management, soil ecology

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The Determination of Normalizing Transformations for Nematode Count Data From Soil Samples and of Efficient Sampling Schemes

Cited by 41 publications

References 0 publications

Mapping quantitative trait loci for resistance to Pratylenchus thornei from synthetic hexaploid wheat in the International Triticeae Mapping Initiative (ITMI) population

Mapping quantitative trait loci for resistance to Pratylenchus thornei from synthetic hexaploid wheat in the International Triticeae Mapping Initiative (ITMI) population

Plant parasitic nematodes and their management in the Maritime provinces of Canada

Nematode biodiversity in Canadian agricultural soils

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