Assessing the Tolerance of Lentil - Rhizobial Strains to Salinity and Drought in vitro Conditions

In this research 220 rhizobial bacteria were isolated from two lentil dryland farming flat plains of Moghan and Koohin. They were then tested in vivo as well as in vitro to make assurance of 184 purified strains of rhizobium leguminosarum biovar vicial (lentil). BTB +YMA culture media with different levels of salinity through NaCl (10, 20,30,40,50dS/m) application were used in salinity tolerance test of lentil rhizobial symbiosis strains. Among the 189 rhizobial strains, 101 were found out to be completely sensitive (EC=10 dS/m), 25 were very tolerant while 10 were classified as super strains, because of their being completely tolerant to salinity. The numbers of Koohin flat plain nurtured rhizobial strains in five salinity levels (in the range of 10 to 50) were respectively 55, 51, 50, 27, 37 while for Moghan flat plain, these numbers were recorded 46,42, 21, 8 and 8, Altogether Koohin flat plain rhizobacteria were more highly salinity tolerant than Moghan flat plain rhizobacteria. Drought tolerance test of rhizobial strains was performed in PEG 6000 +YMA culture media. The drought levels were evaluated as based on optical density of bacterial suspensions prepared for the test. Drought tolerance of rhizobacteria were grouped in 4 levels of completely tolerant, tolerant, sensitive and completely sensitive by as judged through respective optical densities of OD<0.3, OD=0.3-0.4 OD=0.4-0.5, OD>0.5. From among the 10 super strains(completely tolerant) identified, 6 from Moghan flat plain, and 2 super strains from Koohin flat plain were selected. At last it is hoped that the super strains (salinity and drought) identified in this phase of research can be effectively used in later greenhouse studies.