Rhizobium is a genus of aerobic, gram-negative bacteria that establish a symbiotic relationship with leguminous plants. These bacteria enter the root hairs of legumes and form nodules within the roots, where they fix atmospheric nitrogen into a usable form for the plant. This process, known as symbiotic nitrogen fixation, provides essential nutrients to both the plant and the bacteria, making it a crucial ecological and agricultural process.
Each species of Rhizobium typically has a specific host plant, showing a high degree of host specificity. However, this specificity is not absolute, as cross-infection between different rhizobia and even non-legume plants can occur under certain conditions. This flexibility is important for the application of rhizobia in agriculture, especially in areas where legumes are not traditionally grown.
Currently, Rhizobium-based inoculants are widely used as biofertilizers, particularly in legume cultivation. In some regions where legumes were never previously grown, inoculation failed to produce nodules, resulting in very low yields of green manure. However, in fields where legumes have been cultivated before, inoculation with effective rhizobial strains significantly improved crop yields. For example, data from Zhejiang, Jiangxi, and Hunan provinces show that nodule inoculation can increase green manure yields by 10–100% and legume seed production by 10–20%.
In China, commercial rhizobial fertilizers require at least 300 million live bacteria per gram, with less than 1% contamination by other microorganisms. A standard application rate is 6–10 acres per kilogram of seeds. When planting under shaded conditions, the seed coating should be done on the same day. The method includes direct seed coating or mixing with fertilizer during sowing. For instance, peanut rhizobium inoculant can be mixed with cold water (100 grams of bacteria with water), then sown immediately. If used with wolfberry, seeds can be soaked for 6–12 hours, dried, and coated with the bacterial paste before sowing. Alternatively, the paste can be sprayed onto the seeds using a clean sprayer and then sown. Another method involves applying the bacterial agent directly to the soil as a cover fertilizer after watering.
To enhance rhizobial effectiveness, several key practices should be followed:
1. Select highly efficient rhizobial strains that have strong symbiotic compatibility and good nodulation ability.
2. Ensure the quality of the microbial fertilizer, including sufficient viable cell count, low impurity levels, and moisture content below 30%. Store at room temperature, as potency decreases within three months.
3. Master proper inoculation techniques. According to American standards, about 10³–10âµ cells per seed and 10â¶â€“10⸠per grain are recommended. In areas where legumes have been grown before, additional doses may be needed to ensure better results. Adding calcium, magnesium phosphate, lime, boron, or molybdenum can improve bacterial survival and seed germination.
4. Maintain optimal soil moisture, ideally between 40% and 80% of field capacity, especially during the first 10 days after planting when root development is critical.
5. Implement proper field management to support the symbiotic relationship between legumes and Rhizobium throughout the growing season.
By following these practices, farmers can maximize the benefits of biological nitrogen fixation, reduce chemical fertilizer use, and promote sustainable agricultural systems.
Laboratory Equipment,Laboratory Autoclave Class,Moisture Analyzer,Laboratory Analytical Instruments
CHANGZHOU RICHGENIUS MEDLAB CO.,LTD , https://www.rich-gen.com