Effect of rhizobia inoculation on growth and yield traits of soybean varieties in Uganda
Asabaawebwa, Grace Mugabi
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Soybean is an important food and cash crop with approximately 40% protein and 20% oil content. A beneficial feature of soybean is its ability to associate with rhizobia bacteria in its root nodules to fix atmospheric nitrogen through symbiotic association. The soybean production trend in Uganda has increased over the years though yields are still below the potential which is attributed to poor agronomic practices especially lack of use of rhizobia inoculants. This field experiment was conducted during the 2019B season at MUARIK in Wakiso district to evaluate the response of ten soybean varieties (Maksoy 1N, 2N, 3N, 4N, 5N, 6N, Namsoy 4M, NAM1, NAM2, KAB1) to Rhizobia inoculation (Mak-Bio-Fixer). A Split plot design composed of three replications with the main plot having rhizobia and without rhizobia while Sub plots had the soybean varieties. Data was recorded on plant height, total number of root nodules, number of effective root nodules, number of pods per plant and seed yield. Genstat 14th edition was used as the analysis tool to determine the level of significance of the studied traits using ANOVA. Rhizobia inoculation showed a significant influence on plant height, total number of root nodules, number of effective root nodules, number of pods per plant, and seed yield. There was a 17% increase in seed yield with rhizobia inoculation and Namsoy 4M had the highest yield of 1282 kgha-1 followed by Maksoy 6N (1277kgha-1) and NAM1 had the lowest yield (527 kgha-1). There was a 31% increase in number of effective root nodules with Rhizobia inoculation and Maksoy 6N had the highest number of effective root nodules (73) while NAM1 had the lowest (18). These results demonstrate the potential benefits of using Rhizobia inoculation to achieve plant growth promotion, increased nodulation and seed yield of the soybean varieties in the study. However, further studies on these rhizobia inoculation trials should be done in increased locations, increased seasons and on farmers’ fields to validate the results.