Rhizobacteria from Root Nodules of Brazilian Native Legumes Promote-Growth Sorghum bicolor L. Under Drought Conditions

Plant growth-promoting bacteria (PGPB) are bacteria that can enhance protect native plants from abiotic stresses including drought. The inoculation of these PGPB into crop forage plants may increase productivity helping to suppress its growing demand in semiarid regions. The present paper aims to evaluate the Sorghum bicolor L. morphogenic characteristics and growth inoculated with native bacterial isolates from the Brazilian semiarid region under drought conditions. The endophytic bacteria isolated from root nodules of native leguminous plants named Mimosa tenuiflora (isolates - MTBV77, MTP78, MTBV12), Desmanthus pernambucanus (isolates - DPP1) and Mimosa caesalpiniifolia (isolate - MCLR34) were all presumably identified as rhizobia by performing the Polymerase Chain Reaction duplex amplification technique using primers that amplify the nifH and nodC genes. The seeds and roots of sorghum seedlings were inoculated with bacterial isolates. The plants were cultivated in pots under favorable water conditions (80% of the available water) and dry conditions (40% of the available water). The inoculation with bacterial isolates increased emission, elongation and length of the S. bicolor leaves, as well as increased its stem elongation, height, and shoot dry-matter content. However, the magnitude of the effects varied according to the imposed water regime. Thus, rhizobacteria from root nodules of Brazilian native legumes have the potential to promote plant growth. The bacterial isolates DPP1 and MTBV77 attenuate the effects of water stress and promote S. bicolor growth under drought conditions and are therefore promising for the use as an inoculant for S. bicolor sustainable cultivation to forage purposes.