Etude de la symbiose

Abstract

Some strains of rhizobia were isolated from Hedysarum coronarium L. nodules, which was grown at the University campus of Constantine. The strains were selected after a cultural study.. The authentification of these strains allowed the identification of six isolates as Rhizobium hedysari high specific to Sulla nodulation. The development of the 6 strains, in the presence of the ones sp, on selective media classed those rhizobia as fast growing Rhizobium. ThePhysiological characterisation has shown that the optimal temperature is 30°C, the optimum pH is 6,8 and the development of the strains is possible up to 10% NaCl concentration. The numbers of rhizobiums per pelleted seeds, with the sterile peat-based inoculum, goes up to 106 rhizobiums par gram inoculants. The used techniques for bacteria identification (Intrinsic antibiotic resistance and phage sensitivity) permit identification of cultured isolates in Biskra region, due to the absence of specific strain in soil after the estimation of the number of rhizobia in soil (NPP test). The present study permitted the selection of resistance strains to saline stress and temperature ( maximum growth temperature is 40°C and salinity tolerance is inferior to 10%), also the possibility to extend the culture of Sulla in semi-arid area.