Characterization and screening of Native Arbuscular Mycorrhizal Fungi Isolates from Maize (Zea Mays L.) Agro Ecosystems in South Kivu, Democratic Republic of Congo
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Date
2020Author
Malembaka, Reussite, B
Type
ThesisLanguage
enMetadata
Show full item recordAbstract
Maize (Zea mays) is a staple food playing a crucial role in food security and income
generation for many farmers but its productions is constrained by low soils fertility and poor
crops husbandry in DRC. Phosphorus (P) is a critical macronutrient required for maize
production and yet most deficient in the agricultural soils of South Kivu which are inherently
low in P content coupled by high fixation capacity. Maize is a highly mycorrhizal plant but
little is known about its mycorrhization in its cropping system in different agroecologies in
South Kivu. The objectives of this study were to characterize the occurrence and diversity of
native AMF and natural mycorrhizal infectivity potential of soils from maize cropping
systems of South Kivu, DR Congo, and to screen and evaluate the influence of AMF isolates
on maize growth, P and Zn nutrients uptake, and root colonization in dominant acidic soils of
South Kivu namely Ferralsol and Nitisol, under controlled conditions. Soil samples were
collected from maize rhizosphere in 12 villages spread across four territories representative of
the 3 AEZs in South Kivu. A trap culture was initiated and AMF spores were extracted from
field and trap culture soils and species identified using the morphotypes criteria. AMF
diversity, frequency of occurrence and species richness were examined. Roots colonization
was assessed after bio infectivity assay for soils mycorrhizal potential determination. Soil
monospecies inoculums were produced and after screening, five native AMF strains named
AMF1 (Gigaspora gigantea). AMF2 (Gigaspora sp.), AMF3 (Gigaspora margarita), AMF4
(Rhizophagus intraradices) and AMF5 (Acaulospora. reducta) were selected as probable
good AMF biofertilizers. A greenhouse experiment was conducted using single specie
inoculation and these inoculums, applied in a Ferralsol and a Nitisol, were compared to the
inorganic P application, the commercial biofertilizer Rhizatech and the control. Plant height,
chlorophyll content, shoot biomass, shoot P and Zn content, hyphal P contribution and root
colonization were observed. Data were subjected to analysis of variance and means separated
by the Fisher‘s least significant difference. A total of 45 strains of AMF distributed in 11
genera were obtained with the majority being from Gigasporaceae, Acaulosporaceae and
Glomeraceae. Acaulospopra excavata, Acaulospopra bireticulata, Dentiscutata erythropa,
Funneliformis mosseae and Scutellospora pellucida were ubiquitous in all the agroecologies.
Species distribution was mostly influenced by the soil pH and exchangeable Al. At least 22%
of the soils had a mycorrhizal infectivity potential as good as the Rhizatech. The soil AMF
inoculum produced had low spore densities (0 - 2.85 spores g-1) compared to the density of
Rhizatech (4 spores g-1). In the Ferralsol, there was no difference for the P content (p= 0.195),
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but for the Zn content, AMF2 was the highest followed by AMF1. The roots were colonized
equally (p = 0.252) in all the treatments. In the Nitisol, AMF4 equalized with the Pi
application for the shoot biomass, followed by AMF1. The highest root colonization was
observed in AMF4 (31%) and Rhizatech (28%). This is the first report on the study of native
AMF species in South Kivu and there is probably a species that was found for the first time.
The high number of ubiquitous species indicates adaptation to a wide range of
physicochemical environments and could also reduce the cost of production of inoculants.
Other methods of AMF inoculum production like the mass production using in-vitro
techniques or the stimulation of naturally occurring AMF species in the fields should be
tested. Furthermore, there is a need to screen for efficient AMF strains that could improve
nutrients acquisition and maximize plants benefits from the symbiosis. Further studies
assessing the performance of these selected efficient AMF Gipaspora gigantea, Gigaspora
sp., Rhizophagus intraradices and Acaulospora reducta with high spores densities are
recommended.
Publisher
University of Nairobi
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Attribution-NonCommercial-NoDerivs 3.0 United StatesUsage Rights
http://creativecommons.org/licenses/by-nc-nd/3.0/us/Collections
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