Phosphate solubilization capacity, salinity and drought tolerance of rhizobia nodulating chickpea (Cicer arietinum L.)

Abstract

This study aims to select efficient rhizobia strains nodulating chickpea (Cicer arietinum L.) cultivars from the semi-arid zone in Southern Morocco, and evaluated their performance in order to ameliorate the N₂ fixing symbioses of this crop. 68 isolates were obtained from the chickpea nodules, where only 12 strains were selected for their strong potential for nodulation. Many abiotic stress tolerance were assessed for the studied rhizobia such as salinity (0 to 1711 mM), acidity (pH 6.8 to 3.5) and drought (0 to -0.23 MPa PEG₆₀₀₀). Bacterial phosphate-solubilizing ability in NBRIP medium has demonstrated the ability of the studied strains to mobilize significant amounts of P from tricalcium phosphate (TCP),especially the MRP6 strain with a solubilizing index (PSI) of 4.1 and which has also showed high tolerance to salinity (1711 mM), and drought (-0.23 MPa). According to the obtained results, P solubilizing ability was directly correlated to the pH decrease in the medium. The maximum level of orthophosphate was released by MRP13 strains with a value of 1195 mg of P L^-1 after 5 days of incubation.