University of Khartoum

Ability of Four Bacterial Isolates to Solubilize Phosphate, Produce Indole Acetic Acid and Promote Growth of Abu 70 (Sorghum bicolor L.) In vitro

Ability of Four Bacterial Isolates to Solubilize Phosphate, Produce Indole Acetic Acid and Promote Growth of Abu 70 (Sorghum bicolor L.) In vitro

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Title: Ability of Four Bacterial Isolates to Solubilize Phosphate, Produce Indole Acetic Acid and Promote Growth of Abu 70 (Sorghum bicolor L.) In vitro
Author: Osman, Osman Mustafa Ahmed
Abstract: Phosphate solubilizing bacteria are used as plant growth promoters. Therefore in this study, the ability of four bacterial isolates belong to three genera, namely Bacillus, Paenibacillus, and Rhizobium (Sh) isolated from Demonstrative Farm, Faculty of Agriculture, University of Khartoum (Shambat soil), Khartoum state and Rhizobium (Ns) isolated from Demonstrative Farm of Research Station, Authority of Merowe Dam Area for Agricultural Development, Northern state, to solubilize phosphate and produce indole acetic acid (IAA) and their effect on sorghum seedlings were evaluated. The isolates were grown on ammonium yeast extract glucose (AYG) broth, in batch culture to analyze the concentration of soluble phosphate, with simultaneous measurement of the changes in pH. The activity of alkaline Phosphatase (EC3.1.3.1) was determined using para-nitro phenyl phosphate as substrate. IAA production was measured in broth batch culture (YEM for rhizobia and Nutrients broth for Bacillus and Paenibacillus). Pots trial arranged in a factorial complete randomized design was conducted with five treatments and four replicates to determine the effect of isolates on growth and phosphate content of sorghum seedlings in sterile and non-sterile soils. Results showed that the highest concentration of soluble phosphate was obtained by Bacillus (170 mg L-1) followed by Paenibacillus (155 mg L-1), Rhizobium Sh (147.27 mg L-1) and Rhizobium Ns (140 mg L-1). The pH was reduced from the initial values 7 to 4.25, 4.38, 4.38 and 4.45 by Paenibacillus, Rhizobium Sh, Rhizobium Ns and Bacillus sp., respectively. Alkaline phosphatase activity ranged between 1.5 µmol min-1 for Rhizobium Ns to 0.55 µmol min-1 for Bacillus. While in IAA production, Rhizobium Ns produced the highest amount and Paenibacillus represented the lowest amount. The phosphate content of sorghum seedlings was increased significantly with bacterial inoculation. However, shoot length and dry weight were not affected significantly except for Rhizobium Sh and Bacillus in shoot length and Rhizobium Sh and Paenibacillus in dry weight compared to uninoculated treatments in both non-sterile and sterile soils. The phosphate content of sorghum seedlings in non-sterile soil was significantly higher compared to sterile soil. Nevertheless, the Rhizobium Ns achieved the highest seedlings phosphate content (approximately double the uninoculated) among other inocula. It concludes that the four bacterial isolates have the potentiality to serve as inoculants for phosphate solubilization and plant growth promoting bacteria. Response of different crops to the inoculation with these bacterial isolates is crucial to be further studied
Description: 111 Pages
URI: http://khartoumspace.uofk.edu/123456789/26337


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