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| Titel |
Stimulative effect of the fungal biocontrol agent Fusarium oxysporum f.sp. Striga on abundance of nitrifying prokaryotes in a maize rhizosphere |
| VerfasserIn |
Mary Musyoki, Esther Enowashu, Judith Zimmermann, Esther Muema, Henry Wainright, Bernard Vanlauwe, Georg Cadisch, Frank Rasche |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089400
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| Publikation (Nr.) |
 EGU/EGU2014-3601.pdf |
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| Zusammenfassung |
| The integration of resistant crop varieties and Fusarium oxysporum f.sp. strigae (Foxy-2)
strains as biological control agent (BCA) has shown to be an effective control of the weed
Striga hermonthica which is parasitic to several cereals (e.g., maize) cultivated in
Sub-Saharan Africa. Most studies have examined the efficacy of the BCA and its interactions
with host crops, while overlooking the interplay among key microorganisms in the soil
nitrogen (N) cycle. Hence, we postulated that both Foxy-2 and Striga pose threats to the
indigenous plant root-associated microbial communities involved in N cycling through direct
or indirect competition for nutrients and that the application of high quality organic
residues would compensate these effects. The primary objective of this study was thus
to assess the potential impact of Foxy-2 on indigenous nitrifying prokaryotes in
maize rhizosphere cultivated on two distinct soils (sandy Ferric Alisol versus clayey
Humic Nitisol) obtained from Machanga and Embu, respectively, in central Kenya.
These soils were treated with or without Foxy-2 and Striga; and in combination
with high quality (i.e. CN ratio; 13, lignins, 8.9 % and polyphenols, 1.7 %) organic
residues (i.e., Tithonia diversifolia) as N source. Using quantitative polymerase
chain reaction (qPCR), we followed at three pre-defined sampling dates (14, 28
and 42 days after planting) the responses of ammonia-oxidizing archaea (AOA)
and bacteria (AOB), total bacteria and archaea in four treatments of a rhizobox
experiment: (i) Foxy-2 plus Striga (F+S), (ii) Striga only (C+S), (iii) Foxy-2 plus Striga
plus Tithonia diversifolia residues (F+S+T), and (iv) a non-treated control (C).
Overall, the treatment effects on soil microbial populations were, in comparison to
the clayey Embu soil, more pronounced in the sandy Machanga soil. Contrary to
our expectations, we observed a distinct stimulative, but no resource competition
effect of Foxy-2 on the abundance of AOA, as well as total archaeal and bacterial
communities. AOB only showed significant increases in the Machanga soil when
organic residues were added. Furthermore, there were transient detectable significant
increases in total archaea and AOA due to Striga inoculation which also varied with the
soil. The variation in treatment effects in the two soils was highly linked to the
differences in soil properties such as dissolved organic carbon and soil pH which
showed significant (P |
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