<I>Mesorhizobium ciceri</I> and <I>mesorhizobium prulifarium</I> are the dominant symbiotically effective strains on Natoli and Arerti chickpea host varieties

Abstract

It is established that effectiveness in biological nitrogen fixation is a combination of the compatibility of legume host varieties and their endosymbionts working together under their respective agro-ecologies (environments), In order to fully realize the potential of nitrogen fixation and improve production and soil fertility, it is important to pre-screen rhizobial strains that are symbiotically effective and ecologically competitive on their hosts under in vitro environmental conditions. To this end, a total of 24 genetically diverse indigenous Mesorhizobium spp. were screened for their potential to ecological adaptations using standard methods and their symbiotic effectiveness on two chickpea varieties under greenhouse conditions. The data clearly separated ecological tolerant groups; M. plurifarium and M. ciceri and sensitive groups; M. abyssinicae, M. gobiense, M. hawasiense, M. shonense and M. amorphae. They also showed significant difference (p<0.05) in their nodulation features and growth characters on Natoli and Arerti, chickpea varieties. In general, 70% of the Mesorhizobium spp. were highly effective/effective on Natoli and Arerti plants. However, all Mesorhizobium ciceri and Mesorhizobium plurifarium were effective on Natoli variety compared with 71% and 83% on Arerti variety. The strains from both M. hawasiense and M. gobiense were ineffective on both varieties. Four strains: M. ciceri CPR67, M. plurifarium CPR112, M. ciceri CPR40 and M. plurifarium CPR3 were highly effective on both chickpea varieties (SE values 80–100%), and resistant to different in vitro ecological conditions. These strains may potentially improve chickpea production as inoculants, provided they are validated under different field conditions.

Key words/phrases: Arerti variety, Eco-physiological characteristics, Natoli variety, Stress tolerance.