The use of biofertilizers is important for sustainable agriculture, and the use of nodule bacteria and endophytic actinomycetes is an attractive way to enhance plant growth and yield. This study tested the effects of a biofertilizer produced from Bradyrhizobium strains and Streptomyces griseoflavus on leguminous, cereal, and vegetable crops. Nitrogen fixation was measured using the acetylene reduction assay. Under N-limited or N-supplemented conditions, the biofertilizer significantly promoted the shoot and root growth of mung bean, cowpea, and soybean compared with the control. Therefore, the biofertilizer used in this study was effective in mung bean, cowpea, and soybean regardless of N application. In this study, significant increments in plant growth, nodulation, nitrogen fixation, nitrogen, phosphorus, and potassium (NPK) uptake, and seed yield were found in mung beans and soybeans. Therefore, Bradyrhizobium japonicum SAY3-7 plus Bradyrhizobium elkanii BLY3-8 and Streptomyces griseoflavus are effective bacteria that can be used together as biofertilizer for the production of economically important leguminous crops, especially soybean and mung bean. The biofertilizer produced from Bradyrhizobium and S. griseoflavus P4 will be useful for both soybean and mung bean production.

Effects of endophytic actinomycetes and two Bradyrhizobium japonicum (Kirchner 1896) Jordan 1982 strains on growth, nodulation, nitrogen (N) fixation and seed weight of different soybean (Glycine max L. Merr.) varieties from Myanmar (Hinthada), Thailand (SJ5) and Cambodia (DT84) were studied in pot experiments in Thailand. The six treatments consisted of an uninoculated control (T1), a single inoculation with endophytic actinomycetes (Streptomyces sp. strain, P4) (T2), a single inoculation with Bradyrhizobium japonicum strains, USDA110 (T3) or THA7 (T4) and a dual inoculation of P4 with USDA110 (T5) or THA7 (T6). Sterile soil was used for cultivation of all treatments under open field conditions, using tap water for irrigation. N₂ fixation activity of soybean was evaluated by the relative ureide method using xylem solute from the root bleeding sap at the early pod-fill stage. It was found that the single inoculation of P4 did not show significant effects on nodulation, N₂ fixation, shoot dry weight and seed weight at harvest of all soybeans compared with the uninoculated control. In the Hinthada soybean, single inoculation of USDA110 or THA7 increased seed weight while USDA110 improved N₂ fixation (P < 0.05). Dual inoculation of USDA110 and P4 showed the highest shoot N accumulation and seed weight among treatments. In the SJ5 soybean, similar trends to Hinthada were shown, although the THA7 and P4 combination showed the highest shoot N accumulation and seed weight. On the other hand, in the DT84 soybean, there were no significant differences of N₂ fixation and seed weight between USDA110 and THA7 (both single and dual inoculation). In conclusion, dual inoculation of endophytic actinomycetes strain P4 may increase the nodulation and nitrogen fixation in some varieties; however, it is not effective for other varieties.

In order to substitute the use of chemical fertilizers in legume production, there is a need for the production of rhizobial inoculants which are capable of being used as biofertilizers. To achieve this, an effective symbiotic nitrogen (N) fixation between legumes and root nodule bacteria will be essential. Evaluation of effective Myanmar Bradyrhizobium (Jordan 1982) strains isolated from Myanmar soybean (Glycine max L. Merr.) and effects of coinoculation with Streptomyces griseoflavus Krainsky 1914 P4 for N fixation were studied in pot experiments using sterilized vermiculite and Hoagland solution in the Phytotron (25°C and 70% relative humidity) with completely randomized design and three replicates. N fixation ability of soybean was evaluated by acetylene reduction activity (ARA) by gas chromatography. It was found that MAS23 showed a relatively high degree of stability and a high level of ARA per plant on both Yezin-3 and Yezin-6 soybean varieties. In the symbiotic relationship between Bradyrhizobium strains and P4 experiments, the treatments consisted of six Bradyrhizobium strains (MAS23, MAS33, MAS34, MAS43, MAS48 and USDA110) and Streptomyces griseoflavus P4 were evaluated with four Myanmar soybean varieties (Yezin-3, Yezin-6, Hinthada and Shan Sein). In the Yezin-3 soybean variety, the best treatment for ARA per plant was found in the dual inoculation of P4 and MAS34. In the Yezin-6 soybean variety, the highest nodule dry weight was found in dual inoculation of P4 with MAS34 but the highest ARA per plant was observed in the dual inoculation of P4 and MAS23. On the other hand, single inoculation of MAS43 and coinoculation of P4 with MAS48 were significantly higher in N fixation of Hinthada, and coinoculation of P4 with MAS33 was significant improvement of ARA per plant (P < 0.05) in Shan Sein soybean.

Chickpea (Cicer arietinum L.) is one of the world’s main leguminous crops that provide chief source of food for humans. In the present study, we characterized thirty isolates of indigenous chickpea rhizobia from Myanmar based on the sequence analysis of the bacterial 16S rRNA gene. The sequence analysis confirmed that all isolates were categorized and identified as the genus Mesorhizobium and they were conspecific with M. plurifarium, M. muliense, M. tianshanense, and M. sp. This is the first report describing M. muliense, M. tianshanense, and M. plurifurium from different geographical distribution of indigenous mesorhizobia of chickpea in Myanmar. In order to substitute the use of chemical fertilizers in legume production, there is a need for the production of Biofertilizers with rhizobial inoculants. The effectiveness of Myanmar Mesorhizobim strains isolated from soil samples of major chickpea growing areas of Myanmar for plant growth and nitrogen fixation were studied in pot experiments. The nodule dry weight and acetylene reduction activity of the plant inoculated with Mesorhizobium tianshanense SalCP19 was significantly higher than the other tested isolates in Yezin-4 chickpea variety. But, Mesorhizobium sp. SalCP17 was showed high level of acetylene reduction activity per plant in Yezin-6 chickpea variety.