Presence and Frequency of Occurence of Plant Parasitic Nematodes on Coffee (Coffea Arabica L, Rubiaceae) in Ethiopia and the Importance of Endophytic Microorganisms for Biocontrol (eBook, PDF)

• Format: PDF

Produktbeschreibung

A survey was conducted to determine the occurrence and distribution of plant-parasitic nematodes and associated endophytic fungi and bacterial antagonists on coffee in Ethiopia. Soil and root samples were collected from 15 coffee growing agroecologies during the wet season in August 2004 and dry season in April 2006. The dominant plant-parasitic nematode genera found were Helicotylenchus, Scutellonema, Rotylenchus, Xiphinema, Heterodera, Tylenchorhynchus and Quinisulcius. Helicotylenchus predominated throughout the area (65-74%), followed by Xiphinema (29-40%). Nematode densities were generally higher in the wet season than in the dry season, however, relative abundance of nematode taxa was in the same order. For the major plant-parasitic nematode genera, specimens were identified to the following species: Helicotylenchus dihystera, H. multicinctus, H. californicus, H. gerti, Xiphinema insigne, X. basilgoodeyi, Scutellonema paralabiatum, Rotylenchus unisexus, Tylenchorhynchus agri and Quinisulcius capitatus. Nematodes considered to be of economic importance and involved in coffee decline were not detected in this survey. A total of 128 fungi growing endophytically were obtained from surface sterilized coffee roots. The most frequently detected genera were Fusarium and Trichoderma. Nematicidal effects of culture filtrates of these isolates on M. incognita juveniles were observed after 24 h of incubation. Juvenile inactivity ranged from 28% to 81% in which Trichoderma strain ET2 showed the highest level of inactivity up to 81%. Same isolates were tested for their pathogenicity towards M. incognita eggs. Isolates EF1, EF3, EF5, EF6, EF8, EF10, EF11, EU2 and EU4 showed the highest ability to infect eggs with values up to 89%. The percentage of egg pathogenicity was highest for Fusarium spp. Results of replicated greenhouse experiments demonstrated that isolates of Fusarium and Trichoderma reduced the number root-knot nematode egg masses up to 50%. Of all the tested isolates, the F. oxysporum isolate EF11 significantly reduced the number of egg masses in all sets of experiments. Reduction in nematode penetration ranging up to 30% was also recorded in the present study for isolates EF11 and EF10. Endophytic bacteria were isolated and identified by Fatty Acid Methyl Ester-Gas Chromatography (FAME-GC). A total of 201 and 114 endophytic bacteria were isolated and identified during the wet and dry seasons, respectively. The most abundant genera found were Pseudomonas, Bacillus, Agrobacterium, Stenotrophomonas and Enterobacter. Higher population size densities ranging from 5.2 x 103 to 2.07 x 106 cfu g- 1 fresh root were observed during the wet season. Culture filtrates of the bacterial isolates showed nematicidal effects ranged between 38% and 98%. The active strains were: Agrobacterium radiobacter, Bacillus pumillus, B. brevis, B. megaterium, B. mycoides, B. licheniformis, Chryseobacterium balustinum, Cedecea davisae, Cytophaga johnsonae, Lactobacillus paracasei, Micrococcus luteus, M. halobius, Pseudomonas syringae and Stenotrophomonas maltophilia. Bacillus pumillus and B. mycoides were the most effective strains in reducing the number of egg masses and galls up to 39 and 33%, respectively.

---

Dieser Download kann aus rechtlichen Gründen nur mit Rechnungsadresse in A, B, BG, CY, CZ, D, DK, EW, E, FIN, F, GR, HR, H, IRL, I, LT, L, LR, M, NL, PL, P, R, S, SLO, SK ausgeliefert werden.

Produktdetails

• Verlag: Cuvillier Verlag
• Seitenzahl: 166
• Erscheinungstermin: 15. Januar 2008
• Englisch
• ISBN-13: 9783736924925
• Artikelnr.: 49150058