Symbiotic Effectiveness and Phenotypic Characterization of Native Rhizobia Nodulating Lentil (Lens culinaris Medik) Collected from Highlands of Shewa, Ethiopia

Abstract

Screening of symbiotically efficient rhizobial strains is the prerequisite in developing rhizobial inoculants for enhanced productivity of legumes. In this  study, composite soil samples were collected from different lentil growing areas of Shewa. Sixty three lentil (Lens Culinaris Medik) nodulating rhizobial  isolates were characterized for morphological and physiological properties under laboratory condition and evaluated for symbiotic effectiveness under  greenhouse condition. In sand culture, the isolates showed significant (p=0.05) differences for shoot dry weight, nodule number, nodule dry weight,  percentage of symbiotic effectiveness and percentage of total nitrogen and were superior to the negative control. The highest shoot dry weight (0.447 g  per plant) was recorded from plants inoculated with the isolate NSLR-17 and the lowest (0.129 g per plant) from plants inoculated with isolate NSLR-31.  The plants inoculated with the isolate NSLR-2 and NSLR-60 showed the highest (167) and the lowest (46) nodule number per plant, respectively. The  maximum and minimum nodule dry weight per plant was obtained from the isolate NSLR-69 (38.4 mg) and isolate NSLR-66 (15.4 mg), respectively. A few  (5%) of the isolates were highly effective while 59% were effective. The low effective and ineffective isolates accounted for 33% and 1%, respectively. The  isolates showed diversity in tolerance to salinity, different pH, temperature, antibiotics, heavy metals as well as utilization of carbon and nitrogen sources.  Hence, some isolates are competent enough to colonize the rhizosphere under different edaphic and environmental conditions.