Diversity and Plant Growth Promoting Properties of Rhizobacteria Isolated from tef

Abstract

The purpose of this study was to evaluate and assess the plant growth promoting characteristics and diversity of major tef rhizosphere isolates from central Ethiopia. A total of 162 bacteria were isolated from rhizosphere of tef [Eragrostis tef (Zucc.) Trotter] and characterized. While screening using some plant growth promoting characteristics, only about sixty six of the isolates were found to show some characteristics of plant growth promoting rhizobacteria (PGPR) and hence selected for further study. The sixty six isolates were further characterized by several morphological, physiological and biochemical tests and identified to species level using API kit method. Numerical analysis of phenotypic data by a computer cluster analysis using UPGMA (NTSYSpc software version 2.1) was done based on carbohydrate fermentation profile. The isolates displayed diverse morphological, physiological, biochemical and PGPR characteristics [(Phosphate solubilization (52%), antmicrobial property (41%) and HCN production (17%)] in addition to tolerance to a wide range of pH by most of the isolates. The 66 isolates were found to belong to 7 genera and 15 species; two species with each of two sub-species. Analysis of phenotypic data revealed that at boundary levels of 50% average similarity, two major clusters were formed by both Gram-negative and positive isolates while the respective groups form six and seven clusters at about 75% and 78.4% average similarity. The fact that the tef rhizosphere bacteria to be positive for various PGPR characteristics suggests that the isolates have better potential for greenhouse and field testing and application in improving yield of tef.