MORPHOLOGICAL BIOCHEMICAL AND PLANT GROWTH PROMOTING CHARACTERIZATION OF RHIZOBIA ISOLATED FROM ROOT NODULE OF CICER ARIETINUM
Qudratullah Oryakhil, Mohammad Arif Irfan
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Nutrient paucity in the soil poses confront to global production of food. To boost the crop yield and food production, farmers use synthetic nitrogen fertilizers which has unfavorable effects and hazardous to environment and human population. Therefore, there is an urgent need to find alternative strategies that can ensure competitive crop yields, provide environmental safety, and protection while maintain long term ecological balance in agro-ecosystem. Rhizobium, symbiotic bacterium, forms nodules in leguminous plants and fixes nitrogen and plays an important role in improving soil fertility. Hence, screening and selection of proper rhizobial strains is important for biological nitrogen fixation. In the present study, a total 7 rhizobia-like bacteria isolated from root nodules of Cicer arietinum (Chickpea) were characterized for morphological, biochemical and plant growth promoting ability. All the 7 bacterial isolates were identified as rhizobia on the basis of confirmatory test. On the basis of morphological properties, rhizobial colonies on yeast extract mannitol agar (YEMA) medium were round mucoid and white with convex elevation and smooth surface. Under microscopic examination, all the bacterial isolates appeared as Gram negative, rod shaped and motile. Biochemical characterization of rhizobium isolates showed positive reaction with catalase, oxidase, starch hydrolysis, nitrate reduction and urease while most of the rhizobium isolates have negative reaction with citrate utilization and gelatinase enzyme. All the isolates produced plant growth-promoting traits including indole acetic acid, hydrocyanic acid, phosphate solubilization (except AIQ-1 and AIQ-6) ammonia and siderophore (except AIQ-6 and AIQ-7). Out of seven isolates, only 2 isolates exhibited inhibition potential against soil borne plant phytopathogen viz., Rhizoctonia solani under in vitro conditions. This study is a prerequisite to the selection of suitable chickpea rhizobia to develop bio-inoculants for sustainable crop production in Afghanistan.