Evaluation of effective MyanmarBradyrhizobiumstrains isolated from Myanmar soybean and effects of coinoculation withStreptomyces griseoflavusP4 for nitrogen fixation

Abstract

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.

Low-Density Co-Inoculation of Myanmar &lt;i&gt;Bradyrhizobium yuanmingense&lt;/i&gt; MAS34 and &lt;i&gt;Streptomyces griseoflavus&lt;/i&gt; P4 to Enhance Symbiosis and Seed Yield in Soybean Varieties

“…In this study, Yezin-3 (Rj 4 ) responded significantly to the single inoculation of B. yuanmingense MAS34. The MAS34 was isolated from a Rj 4 -genotype host [15]. These findings support the results of previous studies [26][27][28].…”

“…Soe et al [15] stated that S. griseoflavus P4 alone could improve the shoot dry weight of Myanmar soybean varieties. In the present study, the co-inoculation of MAS34 with P4 significantly improved nodule dry weight, plant biomass, N 2 fixation, and seed yield in Yezin-6 but not in Yezin-3.…”

“…Our previous laboratory study revealed that the dual inoculation of S. griseoflavus P4 with Myanmar B. yuanmingense MAS34 significantly influenced the nodule dry weight in Yezin-6 (non-Rj) soybean and the nodule dry weight and N 2 fixation in Yezin-3 (Rj 4 ) soybean [15]. The experimental data suggested the usefulness of further field investigations of selected S. griseoflavus P4 and indigenous B. yuanmingense MAS34 with Yezin-3 (Rj 4 ) and Yezin-6 (non-Rj) soybean varieties.…”

“…Significant stimulation effects were observed following the dual inoculation of P4 and the Bradyrhizobium strain on N uptake in adzuki bean, Thai sweet pea [14], and soybean [15] compared to a bradyrhizobial single inoculation.…”

Plant growth-promoting actinobacteria: a new strategy for enhancing sustainable production and protection of grain legumes

“…The combination of Streptomyces kanamyceticus and Bradyrhizobium japonicum increased nodulation and shoot N composition of soybean by up to 55 and 41%, respectively (Gregor et al 2003). Soe and Yamakawa (2013) examined the effect of co-inoculation of Bradyrhizobium yuanmingense MAS34 and Streptomyces griseoflavus P4 in enhancing nodulation, N 2 fixation, and seed yield in different soybean varieties. The results of these researchers clearly demonstrated the importance of actinobacterial inoculants in growth promotion of leguminous and non-leguminous plants.…”