Agricultural and Biological Research

Screening of endogenous rhizobia strains associated to soybean (Glycine max (L.) Merrill) in Benin for their effectiveness in different types of soils

Mahougnon Charlotte Carmelle Zoundji*, Tobi Moriaque Akplo, Ibouraiman Balogoun, Felix Kouelo Alladassi, Appolinaire Adandonon and Pascal Houngnandan

Identification of elite native rhizobia adapted to local environmental conditions could offer the opportunity to improve symbiotic nitrogen fixation. This study aimed to evaluate the efficiency of endogenous rhizobia strains associated to soybean root in Benin. A total of 102 presumptive rhizobia strains were isolated from root nodules of soybean. Authentication test showed that the highest nodules scores were obtained with the isolates LMSEM 22 (4.8), LMSEM 101 (4.8), LMSEM 97 (3.2), LMSEM 46 (3.1) and LMSEM 25 (2.8). After authentication, 28 isolates and four reference strains (IRAT FA3, STM3043, STM3045 and USDA110) were tested in greenhouse for their symbiotic effectiveness. Results indicated that isolates LMSEM 101 and LMSEM 22 induced the highest nodules number (46 and 30 nodules plant^-1 respectively) and the best dry shoot (7.4 g and 7.1 g plant^-1) and outperformed all the reference strains. Afterwards, the five best performing isolates (LMSEM 22, LMSEM 25, LMSEM 53, LMSEM 97, LMSEM 101) were evaluated on three different soils (S1, S2 and S3) comparing them to reference strains IRAT FA3 and STM3043 in the greenhouse. The isolates LMSEM 22, LMSEM 101 and LMSEM 97 outperformed the two reference strains on the three soils but the highest values were obtained on soils S1 and S2. These results confirm the presence of effective endogenous rhizobia on soybean root in Benin.