Isolation and Characterization of Phosphate Solubliizingbacteria from Some Ethiopian Soils And Their Effect on the Growth of Faba Bean (Vida Faba L.)
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Date
1999-04
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Addis Ababa University
Abstract
Three phosphate solubilizing bacteria coded as Jim41, GimlO and Hagl2 were
isolated from Jimma, Gimbi and Hageremariam soils, respectively. They were
characterized to generic level and found to belong to pseudomonas spp.
Tricalcium phosphate (TCP), rock phosphate (PR) and old bone (OB)
solubilization efficiency of these isolates and one reference commercial
strain (Psellndomon([s striata), introduced from India was studied in the
laboratory at 5, 10, IS and 20 days of incubation. At the end of the specified
incubation date, samples were taken and filtered to remove insoluble
material. The filtrate was then centrifuged and analysed for soluble P using
colorimeter. The result revealed that all PSB isolates solubilized
significantly (P~O.Ol) greater amount of tricalcium phosphate and rock
phosphate over the un inoculated control. The highest amount of
solubilization was achieved with Jim41 followed by GimlO, Hag12 and
Pseudomonas striat([ in that order. Isolate GimlO, Hag12 and P. striata
solubilized significantly (P:'O. 0.01) greater amount of old bone than the
control and isolate Jim41. This suggests that isolate Jim41 cannot be used as
PSB inoculant where old bone is required as insoluble p fertilizer.
Greenhouse pot experiments with regard to the effect of inoculation of PSB
isolates on the growth of faba bean were conducted. The treatments included
two PSB isolates coded as Jim41 and GimlO, and two P-sources (rock
phosphate and triple super phosphate) in various combinations, with and
without Rhizobium. The result showed that following inoculation, the two
PSB inoculants established well in the rhizosphere of faba bean and
displayed the highest population during i h week. Inoculation of PSB
isolates along with the application of rock phosphate significantly (P:'O. 0.01)
improved the dry matter yield of faba bean compared to the control with and
without inoculation of RhizobiulIl. Isolate Jim41 and GimlO inoculated with rock phosp ha te were found to increase the dry matter yield of faba bean by
34 and 39% over the uninoculated control without inoculation of Rhizobium,
and by 33 and 31 % with the inoculation of Rhizobium respectively. The dry
matter yield increment obtained from inoculation of both PSB isolates along
with PR was comparable to that obtained with the application of triple super
phosphate (TSP). This implies that there may be a possibility to use the less
expensive PR together with PSB than the more expensive TSP. Analysis of
plant tissue P content revealed that the PSB inoculants improved the Puptake
of faba bean where PR was applied as p-sources. Inoculation of PSB
has also improved the nitrogen accumulation of faba bean. In the light of the
present finding many of the conclusions are subject to verification. Thus,
future research directions are discussed.
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Biology