Characterization of plant growth promoting bacteria from sugarcane (Saccharum officinarum L) rhizosphere of Wonji-Shoa sugar estate and farmers landraces of Ethiopia

Abstract

Application of chemical fertilizers apart from its low use efficiency, environmental impact and soil quality degradation, was not cost effective in the Ethiopian sugar sector. Thus, looking attractive opportunities which are environmentally friendly approaches and cost effective for the sustainability of the sector like use of biological fertilizers is of paramount importance. Therefore, the objective of this study was to preliminarily screen effective plant growth promoting bacteria from sugarcane fields. One hundred sixteen rhizosphere isolates was taken from sugarcane fields. The isolates were characterized and tested under laboratory condition for their phosphate solubilizing characteristics. Moreover, 23% and m ore than 60% of the isolates could produce indole acetic acid and ammonia, respectively. Isolate HWR27 showed significantly (p≤0.05) the highest solubilization index (3.32) on solid Pikovskaya media. The lowest solubilization index was recorded for the isolate HWR8 (2.33). Three different isolate s (HWR24, HWR27 and HWR48) having plant growth promoting characteristics were evaluated for their solubilization efficiency under three different liquid media (tricalcium phosphate, rock phosphate and bone meal). Among these isolates, HWR48 solubilized the highest amount of phosphate (88.41 mg L-1) from tricalcium phosphate and the same isolate solubilized 33.57 mg L-1 of phosphate from rock phosphate. The solubilization of phosphorus was complimented with reduction in pH. Further research to evaluate the effectiveness of the isolates on growth of sugarcane under greenhouse and field condition would be recommended.