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.

The decline in rice yields as a result of excessive chemical fertilizer (CF) inputs is a matter of great concern in rice-growing regions of Asia. In two-year’s field experiments, the nitrogen, phosphorus, and potassium (NPK) status, growth characteristics and yield of rice were examined by application of poultry manure (PM), cow manure (CM) and compost (CP). Organic fertilizers were applied as EMN (estimated mineralizable N) based on their total N content. Six treatments were assigned in a randomized complete block design: (1) no-N fertilizer (N₀); (2) 50% CF (CF₅₀), (3) 100% CF (CF₁₀₀); 50% CF + 50% EMN from (4) PM or (5) CM or (6) CP. Compared with CF₁₀₀, the CF₅₀PM₅₀ (total N ≥ 4%) accumulated higher N, P and K content in leaf, sheath, panicle and seeds, resulting in greater growth and yield. The CF₅₀PM₅₀ increased yield by 8.69% and 9.70%, dry matter by 4.76% and 5.27% over CF₁₀₀ in both years. The continuous application of CF₅₀CM₅₀ (total N < 4%) and CF₅₀CP₅₀ (total N < 4%) treatments led to similar NPK contents but higher yields than those of CF₁₀₀ treatment in 2018. In conclusion, the organic fertilizer (total N ≥ 4%) with the EMN method enhances higher N availability in each year. Continuous application of organic fertilizer (total N < 4%) over two years effectively increased N availability in the second year. The 50% organic fertilizer (total N ≥ 4%) and 50% CF led to increased NPK availability and rice yields over the 100% CF treatment, reducing CF usage and leading for sustainable agriculture.

This study was conducted to evaluate the effects of Bradyrhizobium japonicum SAY3-7, Bradyrhizobium elkanii BLY3-8, and Streptomyces griseoflavus P4 on the symbiotic effectiveness of soybeans before biofertilizer production, to produce biofertilizer containing the studied three strains (SAY3-7, BLY3-8, and P4), to test the effectiveness of the biofertilizer on soybean varieties, and to assess the varietal effects and interaction effects between variety and biofertilizer on plant growth, nodulation, nitrogen fixation, nutrient absorption, and seed yield. Nitrogen fixation was measured using the acetylene reduction assay and ureide methods. Contents of nutrients (N, P, K, Ca, and Mg) were also measured to calculate their uptakes. In this study, synergistic effects of nitrogen fixation were induced by combined inoculation with SAY3-7, BLY3-8 and P4 in all tested soybean varieties. Therefore, we assumed that an effective biofertilizer could be produced using these effective bacteria (SAY3-7, BLY3-8, and P4). After making biofertilizer using these effective bacteria, packages were stored at 30 °C. The populations of the bacteria in the biofertilizer were maintained at a density of 1 × 10⁸ colony forming units (cfu) g⁻¹ for P4 and 7 × 10⁹ cells g⁻¹ for Bradyrhizobium. Diluting biofertilizer by 10⁻³ proved more effective for nodulation and nitrogen fixation than other dilution treatments. Moreover, this biofertilizer significantly promoted plant growth, nodulation, nitrogen fixation, nutrient uptakes, and seed yield in Yezin-3 and Yezin-6 soybean varieties. Yezin-6 is a more efficient variety than Yezin-3 for improved plant growth, nodulation, nitrogen fixation, nutrient absorption, and seed yield. Taken together, the application of an effective biofertilizer and the use of an efficient soybean variety can play important roles in promoting plant growth, nodulation, nitrogen fixation, and higher seed yield.

Nitrate-tolerant mutants of soybean (Glycine max L. Merr.) cv. Bragg, nts1116 and nts1007, were cultured hydroponically to study the effects of nitrate on plant growth, nodulation, and nitrogen fixation compared to the parent cultivar Bragg. The vegetative growth of nts1116 was the most active. Absorption rate of nitrate increased with the duration of the treatment. The absorption rate was slightly higher in nts1116 compared to ntsl007 and Bragg. Nitrogen accumulation of the nitrate-treated plants through biological nitrogen fixation was larger in the order of ntsl007, nts1116, and Bragg. However, N accumulation from nitrate did not differ among the 3 lines. Nitrate reductase activities in the nodules were the highest in Bragg followed by nts1116 and nts1007, regardless of the nitrate treatment and assay time, and were negatively correlated with the nodule masses. Ureide concentration was the highest in nts1007 followed by nts1116 and Bragg, and was positively correlated with the nodule masses and negatively with the sugar concentration in the leaves in the 3 lines. Total-N concentration was higher in nts1007 than in nts1116 in the. presence of nitrate, while plant growth was more active in nts1116 than in nts1007. The above results indicated that the repression of plant growth in nts1007 was related to the high ureide production of plant associated with the super-abundant nodulation.

Owing to its origin in tropical and subtropical areas, rice is susceptible to cold stress. Low temperatures at the germination and seedling stages can result in seed loss, a delayed transplanting period, and lower final yield. In this study, 181 rice varieties from around the world were investigated for cold tolerance at the germination and seedling stages. At the germination stage, the responses of different rice varieties were examined based on the germination index, coleoptile length, and radicle length at low (13 °C) and control temperatures (25 °C). Significant variations in the germination index, coleoptile length, and radicle length were observed among varieties. Low temperature significantly decreased germination ability, and coleoptile and radicle growth in the studied varieties. At the seedling stage, cold tolerance of the rice varieties was evaluated based on the leaf color score under natural low temperature. Similar to the germination stage, at the seedling stage, significant variation in root and shoot growth was observed in the response of rice varieties to low temperature conditions. Based on the results from both the germination and seedling stages, two varieties (Hei-Chiao-Chui-Li-Hsiang and Ta-Mao-Tao) were selected as the best cold-tolerant varieties. Our results also indicate the benefits of warming treatments to protect rice seedlings from low temperature conditions.

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.