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Comparative rhizosphere microbiological and physicochemical properties of Arachis Hypogeae (Groundnut) and Hibiscus Esculentus (Okro)

O.A.Oyewole, I.N.Okoliegbe, E.E.Akwu

The rhizosphere microbiological and physicochemical properties of Hibiscus esculentus (okro) and Arachis hypogeae (groundnut) were examined for eight weeks. Samples from rhizosphere and non-rhizosphere soil (control) were collected and analyzed using standard microbiological and physicochemical methods. The mean total aerobic bacterial count (cfu/g) of rhizosphere and non-rhizosphere soil for weeks 4, 6 and 8 ranged from 8x109 - 2x1010 and 4x109 - 3x1010 in rhizosphere of okro and groundnut respectively while non-rhizosphere soil had count of 3x108 cfu/g. The mean total anaerobic bacteria count (cfu/g) of rhizosphere and non-rhizosphere soil for weeks 4, 6 and 8 ranged from 1x109-1x1010 and 4x108- 2x1010 in rhizosphere of okro and groundnut respectively while non-rhizosphere soil had a count of 2x108 cfu/g. The mean total fungal count (cfu/g) of rhizosphere and non-rhizosphere soil for weeks 4, 6 and 8 ranges from 1x107 and 2x107- 3x107 in rhizosphere of okro and groundnut respectively while the non-rhizosphere soil had a count 4x106 cfu/g and the mean total actinomycetes count (cfu/g) of rhizosphere and non-rhizosphere soil for weeks 4, 6 and 8 ranged from6x109 - 8x109 and 1x109 - 7x1010 in rhizosphere of okro and groundnut respectively while the non-rhizosphere soil a count of had 2x108 cfu/g. Microorganisms isolated from rhizosphere soils were species of Bacillus, Micrococcus, Streptococcus, Alternaria, Aspergillus, Mucor, Penicillium, Fusarium, Actinomyces, Streptomyces and Norcardia while the microorganisms isolated from the non-rhizosphere soil were species of Bacillus, Micrococcus, Aspergillus, Mucor and Actinomyces. The results of the physicochemical analysis revealed that there were significant differences (P<0.05) in the mean electrical conductivity, potassium, phosphorus, nitrogen, organic carbon (%), organic matter (%), moisture (%) and sulphur between weeks 4, 6 and 8 but there was no significant difference (P>0.05) in their mean pH and sodium. There was also a significant difference (P<0.05) between the microbiological and physicochemical properties of rhizosphere compared with non-rhizosphere soil. The result of this study revealed the presence of several microorganisms in the rhizosphere of okro and groundnut that can serve economic importance.