Effect of calcium salts on growth and plant growth promoting activities of salt tolerant Azotobacterchroococcum
Nivetha N, Vikram KV, Asha AD, Md Aslam Khan, Sangeeta Paul
Effects of chloride and sulphate salts of calcium on the growth and plant growth promoting activities of salt tolerant Azotobacterchroococcum strain H12 were studied. A.chroococcum strain H12 was assessed for tolerance to various concentrations of chloride and sulphate salts of calcium. With increase in the concentration of calcium chloride, there was a decrease in the growth, while calcium sulphate had a beneficial effect of the growth of the microbe. Additionally, salts had no effect on osmolytes proline accumulation in the cells while there was an increase in amino acid content at lower concentration of both the salts. Plant growth promoting activities of these cultures under salt stress were also determined. Nitrogen-fixing ability was not influenced by sulphate salt and enhanced in the presence of chloride salt of calcium. Similarly, IAA production was not affected by sulphate salt and was considerably reduced by supplementation with CaCl2. In contrast, there was beneficial effect of low concentration of chloride salt and negative effect of sulphate salts of calcium on P-solubilization ability. The A. chroococcum culture was observed to be positive for siderophore production and negative for HCN production. Wherefore, the present study confirmed that strain H12 could survive and carry out plant growth promotion activities under saline condition. This culture has the potential to be developed into bioinoculant for saline soils.