Response of Microorganisms in Alfalfa Rhizosphere to Microbial Inoculation

Abstract

Background: Various microorganisms that can have a positive or negative effect on plant development are present in the rhizospheric soil of alfalfa. The research aimed to investigate the impact of two nitrogen-fixing bacteria and two species of the phytopathogen fungus Colletotrichum on the abundance of aminoheterotrophs, nitrifying and denitrifying bacteria in the rhizosphere of three cultivars of alfalfa.Methods: The experiment was carried in vegetation pots as three factorial, where the first factor was alfalfa cultivar (Affinity+Z, K-28 and Perry), the second was the isolate of phytopathogen fungus Colletotrichum: C. trifolii (isolate Coll 4) and C. destructivum (two isolates: Coll-11 and Coll 657); and the third was the variant of bacterial inoculation (Azotobacter chroococcum and Sinorhizobium meliloti). The number of microorganisms was determined by introducing a diluted soil suspension into proper media and counted per one gram of absolutely dry soil.Result: According to the Fisher test applied inoculation microbial inoculation with nitrogen-fixing bacteria and phytopathogen fungus had different effects on the abundance of examined microorganisms in rizospheric soil of different alfalfa cultivars.