Mining Halophytes Rhizobacteria to Enhance Growth of Alfalfa Irrigated by Brackish Groundwater

Halophytes can survive in high salt conditions and are more suitable for recruiting halophytes bacteria. Reinforcing phytoremediation with halophytes rhizobacteria is one of the biological measures for salt-affected land improvement and reclamation. It is still in the infancy stage for lack of knowledge about indigenous strains and intensive trials in the salinized areas of Northwest China. 38 independent isolates were obtained from the rhizosphere of indigenous halophytes (Kalidium foliatum, Lycium ruthenicum and Tamarix chinensis). Isolates HL2-3 and HL2-5 had strongest capacity for solubilizing phosphorus(SP), and isolates HG1-1 and HG2-1 have the best potential for Nitrogenase activity(NA). Moreover, the 4 strains, except for HG2-1 also can secrete indole-3 acetic acid(IAA). HL2-3, HL2-5, HG2-1, HG2-3 were identified as Priestia filamentosus, Bacillus atrophaeus, Paenibacillus peoriae, and Bacillus halotolerans by 16Sr DNA gene sequencing. Non-culturable bacterial species were analyzed by Illumina DNA sequencing. Proteobacteria, Actinobacteria, Bacteroidetes, and Gemmatimonadetes were the most dominant phyla in the rhizosphere of three halophytes. In hydroponic trials, 4 Isolates were analyzed for their potential to stimulate alfalfa growth. B. atrophaeus and B.halotolerans significantly stimulate germination, seedling length and fresh weight in Alfalfa in the presence of brackish water. In pot experiments, we further studied the growth promoting effect of B. atrophaeus, B.halotolerans and their mixed inoculum PGPR on Alfalfa when irrigated by Brackish Groundwater.