Coating Seeds With Probiotics
Unlock the potential of your plants with probiotics
Inoculating seeds with helpful microorganisms before planting is an agricultural practice with enormous potential for enhancing plant growth, soil health, and crop yields. Selecting the right microbial symbionts with seeds can set plants up for better stress tolerance, nutrition, and disease resistance.
Choosing Beneficial Microbes
Many microbes form cooperative symbioses with plants, making them perfect for seed inoculants. (This is in addition to adding microbes into the furrow or seeder water.) Rhizobium bacteria fix nitrogen for legumes, providing ammonia and amino acids that satisfy nitrogen demands. Mycorrhizal fungi like Glomus increase nutrient absorption through root partnerships. Plant growth-promoting rhizobacteria (PGPRs) stimulate growth via hormonal signaling. Protective bacteria such as Bacillus, Lactobacillus, and Pseudomonas generate antifungal metabolites that guard seedlings against pathogens.
Production and Application
Microbial strains are mass-produced through fermentation and then formulated as a seed coating. Polymeric adhesives (polymers?!?) are often applied as they ensure microbes stick to the seed surface before planting. (FYI, I have used calcium lignosulfonate instead of polymers for years!) Inoculants are applied as a liquid drench, powder coating, or integrated into seed pellets. The inoculated seeds then carry their microbial partners into the field or greenhouse.
Early Benefits
When seeds germinate, the microbes immediately colonize the emerging roots and surrounding soil. PGPRs boost seedling vigor and help young plants establish. They are also part of the Rhyzophagy Cycle, so you want them right near the root tips right from when those seeds pop! Mycorrhizae extend the root zone for better access to water and minerals. Nitrogen fixers, such as Azobacter and Rhodopseudomonas palustris, provide nutrients to support growth. Protective microbes also shield against soilborne diseases that commonly infect seedlings.
Long-Term Advantages
Early inoculation fosters lifelong microbial associations. Mycorrhizal relationships initiated during germination persist throughout the plant’s lifecycle, enhancing long-term nutrition. PGPRs multiply along growing roots, continually promoting growth and feeding the plant. Biopesticide bacteria colonize the rhizosphere, guarding against pathogens. These lasting benefits culminate in increased biomass and crop yields.
Field Results
Microbial seed treatments improved yield in trials across various crops over non-inoculated plants. Maize yields increased up to 15% with Azospirillum inoculations. (Galindo et al., 2020) Chickpeas treated with Rhizobium showed 13% higher productivity. (Yadav & Verna, 2014) Rice inoculated with Cyanobacteria (which we covered last Friday) gained up to 14.75% higher yield. (Purwani, 2021) Such enhancements make seed inoculation a promising sustainable tool for meeting global food security challenges. These studies also showed increased uptake of several nutrients, increasing the nutrients inside the plants (our food).
Conclusion
Pre-sowing seed inoculation imbues plants with beneficial microbial partners from day one. Early establishment and lifelong colonization help the symbionts deliver enhanced nutrition, stress resilience, and plant protection – culminating in superior plant performance. Further optimizing and adopting microbial seed technologies can reduce reliance on agricultural chemicals while boosting food production.
Sources:
Galindo, F. S., Pagliari, P. H., Buzetti, S., Rodrigues, W. L., Kondo Santini, J. M., Marcandalli Boleta, E. H., Leonel Rosa, P. A., Rodrigues Nogueira, T. A., Lazarini, E., & Minhoto Teixeira Filho, M. C. (2020). Can silicon applied to correct soil acidity in combination with Azospirillum brasilense inoculation improve nitrogen use efficiency in maize? PLOS ONE, 15(4), e0230954. https://doi.org/10.1371/journal.pone.0230954
J Purwani et al 2021 IOP Conf. Ser.: Earth Environ. Sci. 648 012196
Yadav, J., & Verma, J. P. (2014). Effect of seed inoculation with indigenous Rhizobium and plant growth promoting rhizobacteria on nutrients uptake and yields of chickpea (Cicer arietinum L.). European Journal of Soil Biology, 63, 70-77. https://doi.org/10.1016/j.ejsobi.2014.05.001