Experiment 4: chickpea symbiotic rhizobia identification
To identify any naturalised Mesorhizobium able to nodulate chickpea from the soil, the same three chickpea genotypes were grown in the pots (20 cm diameter × 20 cm tall) filled with the same 5 soils used in Experiment 1 with 4 replicates. The growing environment and management were same to Experiment 1. Nodules were harvested at 6 weeks after sowing, and washed by sonicator, as described above. DNA was extracted from the clean nodules, amplified and sequenced using the same process as the 16S rRNA gene amplicon sequencing.