Isolation and biochemical characterization of Indigenous rhizobia from root nodules of field pea (Pisum sativum L.) and assessment of their bio-inoculants potential on the growth of Bursa variety in Tigray, Ethiopia

Indigenous rhizobia are a suitable alternative bioinoculant to the excessive use and misuse of synthetic fertilizers in agricultural practices to avoid adaptability issues and undesirable effects. This study aimed to identify and characterize indigenous rhizobia from field pea roots, evaluate their plant growth-promoting properties, and assess their inoculation effect on the growth parameters of the newly released Bursa variety. Rhizobia were isolated using Yeast Mannitol agar medium and confirmed through biochemical tests. Plant growth-promoting features of the isolates were assessed in-vitro, while effects of the isolates were tested on Bursa variety using pot experiment. Seven isolates were selected from the total of 21 isolates based on in-vitro and colony-forming unit’s tests for pot experiments under greenhouse. The cross inoculated of the rhizobial isolates was nodulated to the roots of Bursa. Inoculation with these isolates significantly (P < 0.05) increased the shoot /root length, shoot fresh/dry weight, and number of nodules of Bursa compared to the control. All the inoculated plants showed a better performance in their growth parameters than the control. The highest shoot length (33.55 ± 1.37 cm), root length (18.08 ± 0.38 cm), chlorophyll content (3.19 ± 0.3 mg), and dry shoot weight (1.32 ± 0.02 mg) was recorded in Rhizobia-RS4. This study shows that, the isolates can be used as bioinoculants for Bursa variety growing as alternative to chemical fertilizers. Future research should focus on molecular characterization, field trials on another legume species, and packaging of these rhizobia into commercial biofertilizers to use as alternative fertilizers by farmers.