DROUGHT TOLERANCE BY LENTIL RHIZOBIA (RHIZOBIUM-LEGUMINOSARUM) FROM ARID AND SEMIARID AREAS OF PAKISTAN

Ten strains of lentil rhizobia (Rhizobium leguminosarum) were evaluate d for drought tolerance by exposing them to soil moisture potentials o f -0.03, -1.0 and -1.5 MPa. Water availability, rhizobial strain and t ime of exposure to drought had a significant (P less than or equal to 0.001) effect on the number of surviving rhizobia g(-1) of soil, Highe st cell counts were observed at -0.03 MPa, followed by soil maintained at -1.0 and -1.5 MPa. Five strains originating from saline areas show ed significantly (P less than or equal to 0.05) better survival under low water potential after 35 days. Two strains exhibited greatest surv ival under low water potential and produced viable cell counts of more than 10(7) rhizobia g(-1) of soil. These strains could probably be us ed successfully as inoculants for lentil production in arid and semi-a rid environments.