ASSESSMENT OF MICROBIAL ANTAGONISM IN THE RHIZOSPHEREAND NON-RHIZOSPHERE OF POTATO (Solanum tuberosum L.) AT GADAB HASSASA DISTRICT, WEST ARSI ZONE, OROMIA REGIONAL STATE, ETHIOPIA

Abstract

Potato is one of the most staple food sources for many people worldwide. The inoculation of antagonism with potatoes plays a very important role in the worled due to its contribution for human consumption. The rhizosphere is an important source of microbial antagonistic against soilborne fungal pathogens Rhizoctonia solani.This study focuse on the assessment of microbial antagonism in rhizosphere and non-rhizosphere of potato through investigation of potential microbial antagonism against pathogenic rhizoctonia solani. Soil samples were collected from study area by pupesivel and simple random method. Experiments were arranged in Completed Randomized Design with three replications and two control plates. Isolation, identification and determination of antagonisim were take place based on the reducing radial growth of pathogen by fungal antagonist and formation of zone of inhibition by bacterial antagonists. The data of soil weight, colony diameter, zone of inhibition and physicochemical properties of soil were statistically analyzed. The isolates were show antagonism to potato patogenic Rhizoctonia solani and grow on PDA medium for fungal antagonist and NA medium for bacterial antagonists.The test antagonisms inhibited radial colony growth of pathogens at varying degrees. The grow faster occuping more space and producinghigher inhibition zone to showing dominance over the pathogen in dual culture plate there by limiting growth in most of the plates. The colony diameter ranges 10.6mm-27mm for fungalantagonism and the formation of inhibition zone ranges from 11.3mm- 27.9mm for bacterial antagonism at250C and 280C for seven days respectively.The percentage inhibition of fungal antagonists was ranged from 15.6%- 66.9% .Both fungal and bacterialantagonism inoculants had significant (p<0.05) different on percent inhibition and formation of zone of inhibition when compared to the control plate.The antagonistic activity of tested isolates of fungi and bacteria was measured by the radial growth and formation of zone of inhibition on culture media. All antagonists’ isolates were competent to inhibit the growth of pathogens eventhough they show different capacity. This study encourages further isolation of potential microbial antagonists up to species level and beyond.