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- Kurzbeschreibung<p>A survey was conducted to determine the occurrence and distribution of plant-parasitic<BR>nematodes and associated endophytic fungi and bacterial antagonists on coffee in<BR>Ethiopia. Soil and root samples were collected from 15 coffee growing agroecologies<BR>during the wet season in August 2004 and dry season in April 2006. The dominant<BR>plant-parasitic nematode genera found were Helicotylenchus, Scutellonema,<BR>Rotylenchus, Xiphinema, Heterodera, Tylenchorhynchus and Quinisulcius.<BR>Helicotylenchus predominated throughout the area (65-74%), followed by Xiphinema<BR>(29-40%). Nematode densities were generally higher in the wet season than in the dry<BR>season, however, relative abundance of nematode taxa was in the same order. For the<BR>major plant-parasitic nematode genera, specimens were identified to the following<BR>species: Helicotylenchus dihystera, H. multicinctus, H. californicus, H. gerti, Xiphinema<BR>insigne, X. basilgoodeyi, Scutellonema paralabiatum, Rotylenchus unisexus,<BR>Tylenchorhynchus agri and Quinisulcius capitatus. Nematodes considered to be of<BR>economic importance and involved in coffee decline were not detected in this survey.<BR>A total of 128 fungi growing endophytically were obtained from surface sterilized coffee<BR>roots. The most frequently detected genera were Fusarium and Trichoderma.<BR>Nematicidal effects of culture filtrates of these isolates on M. incognita juveniles were<BR>observed after 24 h of incubation. Juvenile inactivity ranged from 28% to 81% in which<BR>Trichoderma strain ET2 showed the highest level of inactivity up to 81%. Same isolates<BR>were tested for their pathogenicity towards M. incognita eggs. Isolates EF1, EF3, EF5,<BR>EF6, EF8, EF10, EF11, EU2 and EU4 showed the highest ability to infect eggs with<BR>values up to 89%. The percentage of egg pathogenicity was highest for Fusarium spp.<BR>Results of replicated greenhouse experiments demonstrated that isolates of Fusarium<BR>and Trichoderma reduced the number root-knot nematode egg masses up to 50%. Of<BR>all the tested isolates, the F. oxysporum isolate EF11 significantly reduced the number<BR>of egg masses in all sets of experiments. Reduction in nematode penetration ranging up<BR>to 30% was also recorded in the present study for isolates EF11 and EF10.<BR>Endophytic bacteria were isolated and identified by Fatty Acid Methyl Ester-Gas<BR>Chromatography (FAME-GC). A total of 201 and 114 endophytic bacteria were isolated<BR>and identified during the wet and dry seasons, respectively. The most abundant genera<BR>found were Pseudomonas, Bacillus, Agrobacterium, Stenotrophomonas and<BR>Enterobacter. Higher population size densities ranging from 5.2 x 103 to 2
- AutorTesfamariam Mekete
- VerlagCuvillier Verlag
- Seiten153 Seiten
- Gewicht230 g
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