Phenotypic characteristics of rhizobia isolates nodulating Acacia species in the arid and Saharan regions of Morocco

The phenotypic characteristics of 48 isolates obtained from root nodules of four Acacia species (Acacia cyanophylla, A. gummifera, A. horrida and A. r addiana) growing in soils collected from the arid and Saharan regions of Mo rocco were studied. The rhizobia were very diverse with respect to their cr oss-nodulation patterns, as well as their physiological and biochemical pro perties. Dendrograms obtained through computer numerical analysis of 52 phe notypic characteristics showed that isolates could fit into four clusters b elow the boundary level of 0.85 average distance and that they were very di stinct from the reference strains. Some interesting isolates for inoculatio n trials have been identified. They were able to grow at pH ranging from 4 to 9, tolerate a high salt concentration (3% NaCl) and grew at a maximum te mperature between 35 and 40 degrees C.