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Identity and diversity of migratory plant-parasitic nematodes on coffee and their sustainable management via crop resistance in Vietnam

(2010)
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Abstract
The thesis is a study into plant-parasitic nematodes on coffee in Vietnam with special focus on migratory endoparasitic nematodes of the Pratylenchidae considering their diversity in morphology, morphometrics and molecular features, as well as their pathogenicity on coffee and their suitable management. The survey done at the start of the study considered major coffee producing areas in Vietnam. Twenty-one plant-parasitic nematodes species were recovered from rhizosphere soil. Distribution and importance of plant-parasitic nematodes were recorded and discussed. Undescribed species belonging to the Pratylenchidae were also detected and described as Apratylenchus vietnamensis and A. binhi, both classified within a new subfamily Apratylenchinae. Seven isolates of P. coffeae were used to study the intraspecific variability. Quite high diversity was observed in morphology and morphometrics. Some main characters such as tail shape and pharyngeal lobe length were found to overlap with those of P. pseudocoffeae, P. loosi and P. jaehni. D2D3 and ITS rDNA sequences of the seven isolates showed a low divergence. The isolates from Vietnam were classified inside a big clade of P. coffeae populations of which the sequences are available in Genbank. The degree of variability of morphometrics and morphological characters amongst Radopholus species on coffee in Vietnam was also documented. One Radopholus population from the Western Highland was described as a new species (Radopholus sp. 1). The CDA (Canonical discriminant analysis) separated R. duriophilus, R. arabocoffeae, Radopholus sp. 1 and R. similis by some morphological characters of the female. Phylogenetic analysis of ITS-rDNA sequences and sequences from the D2/D3 expansion region of the 28S rRNA gene classified R. duriophilus, R. arabocoffeae and Radopholus sp. 1 from Vietnam as a separate group from R. similis. The effect of initial population densities (Pi = 0, 1, 2, 4, 8, 16, 32, 64, 128 and 256 nematodes per cm3 soil) on plant growth and nematode multiplication was studied for P. coffeae and R. arabocoffeae at different days after inoculation (dai). The data were fitted to the Seinhorst damage model Y = m + (1-m).z (Pi-T). Tolerance limit (T) for P. coffeae was zero for the height and the diameter of the coffee plants at all observations. The growth of coffee was reduced at all inoculation levels for both species. It was observed that P. coffeae mainly destroyed lateral roots rather than tap roots, whereas R. arabocoffeae reduced tap root length rather than the lateral roots. Isolates of P. coffeae and R. arabocoffeae differ in their reproductive fitness, which is linked to their pathogenicity. Pratylenchus coffeae and R. arabocoffeae are highly pathogenic and able to multiply on Arabica coffee cv. Catimor both in the field and greenhouse. The population density of R. arabocoffeae and P. coffeae was studied after the dead and removal of severely damaged coffee plants (Coffea arabica cv. Catimor) in a field naturally infested with both nematodes. Both species were found up to 70 cm depth. Densities of R. arabocoffeae and P. coffeae populations declined exponentially (y=ae-bt) over time in all soil layers. No nematodes were found in soil and root fragments 10 and 11 months after the removal of the infected coffee plants for R. arabocoffeae and P. coffeae, respectively. Selection of imported varieties and high yield varieties of Arabica coffee in Vietnam were evaluated for resistance to both plant-parasitic nematode species in the Northern area of Vietnam. The same experiments were carried out with hybrid arabica coffee; three selected clones of Robusta coffee and one clone of C. excelsa were screened in The Western Highland.
Keywords
tolerance, population dynamic, management, resistance, coffee, Apratylenchus, Pratylenchus, Radopholus, Vietnam

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Please use this url to cite or link to this publication:

Chicago
Trinh Quang, Phap. 2010. “Identity and Diversity of Migratory Plant-parasitic Nematodes on Coffee and Their Sustainable Management via Crop Resistance in Vietnam”. Ghent, Belgium: Ghent University. Faculty of Bioscience Engineering.
APA
Trinh Quang, P. (2010). Identity and diversity of migratory plant-parasitic nematodes on coffee and their sustainable management via crop resistance in Vietnam. Ghent University. Faculty of Bioscience Engineering, Ghent, Belgium.
Vancouver
1.
Trinh Quang P. Identity and diversity of migratory plant-parasitic nematodes on coffee and their sustainable management via crop resistance in Vietnam. [Ghent, Belgium]: Ghent University. Faculty of Bioscience Engineering; 2010.
MLA
Trinh Quang, Phap. “Identity and Diversity of Migratory Plant-parasitic Nematodes on Coffee and Their Sustainable Management via Crop Resistance in Vietnam.” 2010 : n. pag. Print.
@phdthesis{1077724,
  abstract     = {The thesis is a study into plant-parasitic nematodes on coffee in Vietnam with special focus on migratory endoparasitic nematodes of the Pratylenchidae considering their diversity in morphology, morphometrics and molecular features, as well as their pathogenicity on coffee and their suitable management.
The survey done at the start of the study considered major coffee producing areas in Vietnam. Twenty-one plant-parasitic nematodes species were recovered from rhizosphere soil. Distribution and importance of plant-parasitic nematodes were recorded and discussed. Undescribed species belonging to the Pratylenchidae were also detected and described as Apratylenchus vietnamensis and A. binhi, both classified within a new subfamily Apratylenchinae. 
Seven isolates of P. coffeae were used to study the intraspecific variability. Quite high diversity was observed in morphology and morphometrics. Some main characters such as tail shape and pharyngeal lobe length were found to overlap with those of P. pseudocoffeae, P. loosi and P. jaehni. D2D3 and ITS rDNA sequences of the seven isolates showed a low divergence. The isolates from Vietnam were classified inside a big clade of P. coffeae populations of which the sequences are available in Genbank. 
The degree of variability of morphometrics and morphological characters amongst Radopholus species on coffee in Vietnam was also documented. One Radopholus population from the Western Highland was described as a new species (Radopholus sp. 1). The CDA (Canonical discriminant analysis) separated R. duriophilus, R. arabocoffeae, Radopholus sp. 1 and R. similis by some morphological characters of the female. Phylogenetic analysis of ITS-rDNA sequences and sequences from the D2/D3 expansion region of the 28S rRNA gene classified R. duriophilus, R. arabocoffeae and Radopholus sp. 1 from Vietnam as a separate group from R. similis. 
The effect of initial population densities (Pi = 0, 1, 2, 4, 8, 16, 32, 64, 128 and 256 nematodes per cm3 soil) on plant growth and nematode multiplication was studied for P. coffeae and R. arabocoffeae at different days after inoculation (dai). The data were fitted to the Seinhorst damage model Y = m + (1-m).z (Pi-T). Tolerance limit (T) for P. coffeae was zero for the height and the diameter of the coffee plants at all observations. The growth of coffee was reduced at all inoculation levels for both species. It was observed that P. coffeae mainly destroyed lateral roots rather than tap roots, whereas R. arabocoffeae reduced tap root length rather than the lateral roots. 
Isolates of P. coffeae and R. arabocoffeae differ in their reproductive fitness, which is linked to their pathogenicity. Pratylenchus coffeae and R. arabocoffeae are highly pathogenic and able to multiply on Arabica coffee cv. Catimor both in the field and greenhouse. 
The population density of R. arabocoffeae and P. coffeae was studied after the dead and removal of severely damaged coffee plants (Coffea arabica cv. Catimor) in a field naturally infested with both nematodes. Both species were found up to 70 cm depth. Densities of R. arabocoffeae and P. coffeae populations declined exponentially (y=ae-bt) over time in all soil layers. No nematodes were found in soil and root fragments 10 and 11 months after the removal of the infected coffee plants for R. arabocoffeae and P. coffeae, respectively. 
Selection of imported varieties and high yield varieties of Arabica coffee in Vietnam were evaluated for resistance to both plant-parasitic nematode species in the Northern area of Vietnam. The same experiments were carried out with hybrid arabica coffee; three selected clones of Robusta coffee and one clone of C. excelsa were screened in The Western Highland.},
  author       = {Trinh Quang, Phap},
  isbn         = {9789059894075},
  keyword      = {tolerance,population dynamic,management,resistance,coffee,Apratylenchus,Pratylenchus,Radopholus,Vietnam},
  language     = {eng},
  pages        = {X, 171},
  publisher    = {Ghent University. Faculty of Bioscience Engineering},
  school       = {Ghent University},
  title        = {Identity and diversity of migratory plant-parasitic nematodes on coffee and their sustainable management via crop resistance in Vietnam},
  year         = {2010},
}