Enhancement of Faba Bean (Vicia faba L.) Yield Using Elite Rhizobial Inoculants on Acidic Soils of the Central Highlands of Ethiopia

This study was intended to evaluate the inoculation response of faba bean to six indigenous rhizobial isolates, 100 kg ha-1 DAP as a positive control and non-inoculated negative control under acidic field conditions at Damotu (in 2019) and Chiri (in 2020) of Ejere district, Ethiopia. The experiments were laid out in a randomized complete block design (RCBD) with three replications and a plot size of 4 m x 3 m. The result confirmed the existence of a significant difference between treatments (p ≤ 0.05) in aboveground biomass, grain, and haulms yields. The highest grain yields (3378.3 kg ha-1 and 3286.7 kg ha-1) were obtained from inoculation of rhizobial isolate FB-EM-11 at both experimental sites. The second higher grain yields were obtained from inoculation of rhizobial isolates FB-NS-03 (3376.7 kg ha-1) at Damotu and FB-EM-07 (3269.5 kg ha-1) at Chiri. Based on the two successive years’ grain yield response, FB-EM-11(3332.6 kg ha-1) and FB-NS-03(3198 kg ha-1) were the first and the second most performing isolates at Ejere district. Moreover, from the partial budget analysis result, FB-EM-11, FB-NS-03, and FB-EM-07 were the most promising isolates that showed the higher marginal rate of return 8309%, 7344%, and 6865%, respectively. Thus, these rhizobial isolates are the best promising candidate for further verification over the farmers’ field at different agro-ecologies to identify candidates for the development of commercial faba bean rhizobial inoculants in acid-prone faba bean growing areas of Ethiopia.