IMPACT OF RHIZOSPHERIC, NODULATION AND SOIL MICROBIOME ON SOYBEAN AND RICE GROWTH FOR SUSTAINABLE AGRICULTURE

Abstract

Microorganisms are critical for the survival of life on Earth, but we know very little about the vast majority ofmicrobes. We studied the culturable soybean root, soil, and nodules microbiome here. Thirty bacterial sampleswere isolated from different localities of soybean crops, including soil, root, and nodules, to assess their abilityfor plant growth promotion. To evaluate the richness and diversity in the root and soil, we performed the mostprobable number (MPN) test. Seven of the bacterial isolates were able to produce cellulase, in which JSW1 andJSW6 were most efficient with 2.56 and 2.05 cellulolytic index. All isolates were able to grow and utilizedpectin, in which JSW2 and JSW3 were most efficient with 0.8 and 0.66 pectinolytic index. Pikovskaya mediamodified with TCP JSW1 and JSW2 showed a 3.0 and 2.33 solubility index, and on CaCO 3 media, the JSW1strain produced a 1.58 solubilization index. All bacterial isolates were phylogenetically identified by sequencingand analyzing the 16S rRNA gene. Under controlled conditions, consortia, Pantoea dispersa, and Rhizobiumsp. isolates considerably improved rice root dry weight by 53%, 75%, and 69% and shoot dry weight by 85%,71%, and 76%. Based on in vitro characterization, the potential bacteria Pantoea dispersa, Pseudomonaskoreensis, and Rhizobium sp. were selected to be evaluated for plant growth, nodulation, and grain yield underfield experiment. Under field conditions, Rhizobium sp and Pseudomonas koreensis were found best as singleinoculation by improving 53% and 49% grain yield, respectively. These potential bacteria could be used asbiofertilizers for soybean crop productivity.