Improvement of Acacia modesta Growth and Phytochemical Constituents by Phosphate Solubilizing and Siderophore Producing Bacteria

In arid areas, Acacia modesta (Wall) is considered as key forage species for regional communities. Four plant growth promoting rhizobacteria bacteria (PGPR); Enterobacter cancerogenus, Acinetobacter lwoffii, Brevundimonas vesicularis were isolated from the rhizosphere of A. modesta, and Aeromonas caviae was isolated from roots. All the isolates were capable to solubilize phosphorus and produce indole acetic acid (IAA). B. vesicularis had highest P-solubilization and IAA production potential. E. cancerogenus exhibited highest siderophore production. All bacterial isolates were applied alone and in the form of consortium on A. modesta by seed soaking. After 60 days of sowing, higher contents of phosphorus were recorded in inoculated soil. Secondary metabolites phenol, tannin, glycoside, lignin, saponin and flavonoid were spotted in treated plants. Higher Phenol, tannin, saponin, flavonoid and antioxidants (superoxide dismutase and peroxidase) in the leaves were recorded in single and consortium inoculation. Inoculation of PGPR alone and in consortium showed higher plant height, collar diameter, branches number, branches length, number of leaflets, and length of leaflets of A. modesta. The findings reveals that the B. vesicularis had better inoculation effects on phytochemical constituents and growth indices of A. modesta, while consortium had best results.