Multiplication and survival of chickpea and bean rhizobia in dry soils: The influence of strains, matric potential and soil texture

Multiplication and survival of two strains of chickpea rhizobia and two strains of bean rhizobia was studied in soils varying in texture under different constant soil matric potentials (−0.03, −0.1, −1.5 and −5.0 MPa). A selective medium containing two antibiotics was employed for the recovery and enumeration of rhizobia cells introduced into soil. Rhizobia populations significantly increased in all soils at the four matric potentials used 5 days after inoculation except those in acid washed sand and that of strain Ch184strspc in Katumani soil. During the following incubation period of 65 days, populations decreased at various rates. The results showed that there were very significant differences in multiplication and survival in response to the effect of matric potential, rhizobia strain, soil type and the interactions between these factors. However, the effects of soil type and strain were much greater than that of matric potential over the range of potentials used.