Abstract :
Symbiotic nitrogen fixation (SNF) is a fundamental biological process that enhances legume productivity while reducing dependence on synthetic nitrogen fertilizers. However, its efficiency varies considerably across production systems because it is regulated by complex interactions among plant genetics, rhizobial compatibility, physiological processes, environmental conditions, and agronomic management. This review synthesizes current knowledge on the mechanisms regulating SNF and critically examines the biological, environmental, and management factors that determine its effectiveness. The review integrates evidence from the literature on the molecular basis of legume–rhizobium symbiosis, physiological regulation of nitrogen fixation, the influence of soil properties, nutrient availability, climatic stresses, and agronomic practices, and evaluates emerging technologies and future research directions. The synthesis demonstrates that SNF performance is inherently context-dependent and cannot be optimized through a single intervention. Instead, successful nitrogen fixation requires coordinated management of host genotype, rhizobial inoculants, soil fertility, water availability, and crop management while accounting for local environmental conditions. The review also identifies important knowledge gaps, including limited long-term field validation, insufficient integration of multidisciplinary approaches, and challenges in translating emerging genomic, microbial, and precision agriculture technologies into practical farming systems. Overall, this review emphasizes that integrated, site-specific management combined with continued advances in biofertilizer development and multidisciplinary research is essential for maximizing SNF efficiency, reducing reliance on synthetic nitrogen fertilizers, and supporting sustainable, climate-resilient agricultural production.
Keywords :
Biofertilizers, Biological nitrogen fixation, Integrated nutrient management, Legume–rhizobium symbiosis, Nitrogen fixation efficiencyReferences :
- Ayilara, M. S., Abberton, M., Oyatomi, O. A., Odeyemi, O., & Babalola, O. O. (2022). Potentials of underutilized legumes in food security. Frontiers in Soil Science, 2, 1020193. https://doi.org/10.3389/fsoil.2022.1020193
- Bacanamwo, M., & Purcell, L. C. (1999). Soybean dry matter and nitrogen accumulation responses to flooding stress, N sources and hypoxia. Journal of Experimental Botany, *50*(334), 689–696. https://doi.org/10.1093/jxb/50.334.689
- Burghardt, L. T., & diCenzo, G. C. (2023). The evolutionary ecology of rhizobia: Multiple facets of competition and cooperation. FEMS Microbiology Reviews, *47*(1), fuac044. https://doi.org/10.1093/femsre/fuac044
- Chianu, J. N., Nkonya, E. M., Mairura, F. S., Chianu, J. N., & Akinnifesi, F. K. (2011). Biological nitrogen fixation and socioeconomic factors for legume production in sub‑Saharan Africa: A review. Agronomy for Sustainable Development, *31*(1), 139–154. https://doi.org/10.1051/agro/2010004
- de Bruijn, F. J., & Hungria, M. (2022). Biological nitrogen fixation. In Good Microbes in Medicine, Food Production, Biotechnology, Bioremediation, and Agriculture. Wiley. https://doi.org/10.1002/9781119762621.ch37
- Deaker, R., Roughley, R. J., & Kennedy, I. R. (2004). Legume seed inoculation technology—a review. Soil Biology and Biochemistry, *36*(8), 1275–1288. https://doi.org/10.1016/j.soilbio.2004.04.009
- Dixon, R., & Kahn, D. (2004). Genetic regulation of biological nitrogen fixation. Nature Reviews Microbiology, *2*(8), 621–631. https://doi.org/10.1038/nrmicro954
- Erisman, J. W., Sutton, M. A., Galloway, J., Klimont, Z., & Winiwarter, W. (2008). How a century of ammonia synthesis changed the world. Nature Geoscience, 1(10), 636–639. https://doi.org/10.1038/ngeo325
- (2022). The State of Food and Agriculture 2022: Leveraging automation in agriculture for transforming agrifood systems. Food and Agriculture Organization of the United Nations. https://doi.org/10.4060/cb9479en
- Ferguson, B. J., Indrasumunar, A., Hayashi, S., Lin, M. H., Lin, Y. H., Reid, D. E., & Gresshoff, P. M. (2019). Molecular analysis of legume nodule development and autoregulation. Journal of Integrative Plant Biology, *61*(1), 60–77. https://doi.org/10.1111/jipb.12778
- Fowler, D., Coyle, M., Skiba, U., Sutton, M. A., Cape, J. N., Reis, S., Sheppard, L. J., Jenkins, A., Grizzetti, B., Galloway, J. N., Vitousek, P., Leach, A., Bouwman, A. F., Butterbach‑Bahl, K., Dentener, F., Stevenson, D., Amann, M., & Voss, M. (2013). The global nitrogen cycle in the twenty‑first century. Philosophical Transactions of the Royal Society B, *368*(1621), 20130164. https://doi.org/10.1098/rstb.2013.0164
- Gage, D. J. (2004). Infection and invasion of roots by symbiotic, nitrogen‑fixing rhizobia during nodulation of temperate legumes. Microbiology and Molecular Biology Reviews, *68*(2), 280–300. https://doi.org/10.1128/MMBR.68.2.280-300.2004
- Galloway, J. N., Dentener, F. J., Capone, D. G., Boyer, E. W., Howarth, R. W., Seitzinger, S. P., Asner, G. P., Cleveland, C. C., Green, P. A., Holland, E. A., Karl, D. M., Michaels, A. F., Porter, J. H., Townsend, A. R., & Vörösmarty, C. J. (2004). Nitrogen cycles: Past, present, and future. Biogeochemistry, *70*(2), 153–226. https://doi.org/10.1007/s10533-004-0370-0
- Galloway, J. N., Townsend, A. R., Erisman, J. W., et al. (2008). Transformation of the nitrogen cycle: Recent trends, questions, and potential solutions. Science, 320(5878), 889–892. https://doi.org/10.1126/science.1136674
- Gebbers, R., & Adamchuk, V. I. (2010). Precision agriculture and food security. Science, *327*(5967), 828–831. https://doi.org/10.1126/science.1183899
- Geddes, B. A., Ryu, M. H., & Mus, F. (2015). Use of synthetic biology tools to improve nitrogen fixation. Current Opinion in Biotechnology, *32*, 216–222. https://doi.org/10.1016/j.copbio.2015.01.003
- Giller, K. E. (2001). Nitrogen fixation in tropical cropping systems(2nd ed.). CABI Publishing.
- Graham, P. H., & Vance, C. P. (2003). Legumes: Importance and constraints to greater use. Plant Physiology, *131*(3), 872–877. https://doi.org/10.1104/pp.017004
- Haskett, T. L., Tkacz, A., & Poole, P. S. (2021). Engineering rhizobacteria for sustainable agriculture. The ISME Journal, *15*(4), 949–964. https://doi.org/10.1038/s41396-020-00835-4
- (2023). Climate Change 2023: Synthesis Report. Intergovernmental Panel on Climate Change. https://doi.org/10.59327/IPCC/AR6-9789291691647
- Jensen, E. S., Peoples, M. B., Boddey, R. M., Gresshoff, P. M., Hauggaard‑Nielsen, H., Alves, B. J. R., & Morrison, M. J. (2012). Legumes for mitigation of climate change and the provision of feedstock for biofuels and biorefineries. A review. Agronomy for Sustainable Development, *32*(2), 329–364. https://doi.org/10.1007/s13593-011-0056-7
- Kaiser, B. N., Gridley, K. L., Brady, J. N., Phillips, T., & Tyerman, S. D. (2005). The role of molybdenum in agricultural plant production. Annals of Botany, *96*(5), 745–754. https://doi.org/10.1093/aob/mci226
- Kebede, E. (2021). Contribution, utilization, and improvement of legumes-driven biological nitrogen fixation in agricultural systems. Frontiers in Sustainable Food Systems, 5, 767998. https://doi.org/10.3389/fsufs.2021.767998
- Lam, S. K., Chen, D., Norton, R., Armstrong, R., & Mosier, A. R. (2012). Nitrogen dynamics in grain crop and legume pasture systems under elevated atmospheric carbon dioxide concentration: A meta‑analysis. Global Change Biology, *18*(9), 2853–2859. https://doi.org/10.1111/j.1365-2486.2012.02758.x
- Larimer, A. L., Bever, J. D., & Clay, K. (2010). The interactive effects of plant microbial symbionts: A review and meta‑analysis. Symbiosis, *51*(2), 139–148. https://doi.org/10.1007/s13199-010-0083-1
- Lerouge, P., Roche, P., Faucher, C., Maillet, F., Truchet, G., Promé, J. C., & Dénarié, J. (1990). Symbiotic host‑specificity of Rhizobium melilotiis determined by a sulphated and acylated glucosamine oligosaccharide signal. Nature, *344*(6268), 781–784. https://doi.org/10.1038/344781a0
- Masson‑Boivin, C., & Sachs, J. L. (2018). Symbiotic nitrogen fixation by rhizobia — the roots of a success story. Current Opinion in Plant Biology, *44*, 7–15. https://doi.org/10.1016/j.pbi.2017.12.001
- Oldroyd, G. E. D. (2013). Speak, friend, and enter: Signalling systems that promote beneficial symbiotic associations in plants. Nature Reviews Microbiology, *11*(4), 252–263. https://doi.org/10.1038/nrmicro2990
- Ott, T., van Dongen, J. T., Günther, C., Krusell, L., Desbrosses, G., Vigeolas, H., Bock, V., Czechowski, T., Geigenberger, P., & Udvardi, M. K. (2005). Symbiotic leghemoglobins are crucial for nitrogen fixation in legume root nodules but not for general plant growth and development. Current Biology, *15*(6), 531–535. https://doi.org/10.1016/j.cub.2005.01.042
- Palmero, F., Fernandez, J. A., Garcia, F. O., Haro, R. J., Prasad, P. V. V., Salvagiotti, F., & Ciampitti, I. A. (2022). A quantitative review into the contributions of biological nitrogen fixation to agricultural systems by grain legumes. European Journal of Agronomy, 136, 126514. https://doi.org/10.1016/j.eja.2022.126514
- Peoples, M. B., Brockwell, J., Herridge, D. F., et al. (2009). The contributions of nitrogen-fixing crop legumes to the productivity of agricultural systems. Symbiosis, 48, 1–17. https://doi.org/10.1007/BF03179980
- Perret, X., Staehelin, C., & Broughton, W. J. (2000). Molecular basis of symbiotic promiscuity. Microbiology and Molecular Biology Reviews, *64*(1), 180–201. https://doi.org/10.1128/MMBR.64.1.180-201.2000
- Raliya, R., Saharan, V., Dimkpa, C., & Biswas, P. (2018). Nanofertilizer for precision and sustainable agriculture: Current state and future perspectives. Journal of Agricultural and Food Chemistry, *66*(26), 6487–6503. https://doi.org/10.1021/acs.jafc.7b02178
- Raun, W. R., & Johnson, G. V. (1999). Improving nitrogen use efficiency for cereal production. Agronomy Journal, 91(3), 357–363. https://doi.org/10.2134/agronj1999.00021962009100030001x
- Ravishankara, A. R., Daniel, J. S., & Portmann, R. W. (2009). Nitrous oxide (N₂O): The dominant ozone-depleting substance emitted in the 21st century. Science, 326(5949), 123–125. https://doi.org/10.1126/science.1176985
- Rocha, I., Ma, Y., Souza-Alonso, P., Vosátka, M., Freitas, H., & Oliveira, R. S. (2019). Seed coating: A tool for delivering beneficial microbes to agricultural crops. Frontiers in Plant Science, *10*, 1357. https://doi.org/10.3389/fpls.2019.01357
- Rogers, A., Ainsworth, E. A., & Leakey, A. D. B. (2009). Will elevated carbon dioxide concentration amplify the benefits of nitrogen fixation in legumes? Plant Physiology, *151*(3), 1009–1016. https://doi.org/10.1104/pp.109.144113
- Salvagiotti, F., Cassman, K. G., Specht, J. E., Walters, D. T., Weiss, A., & Dobermann, A. (2008). Nitrogen uptake, fixation and response to fertilizer N in soybeans: A review. Field Crops Research, *108*(1), 1–13. https://doi.org/10.1016/j.fcr.2008.03.001
- Santos, M. S., Nogueira, M. A., & Hungria, M. (2019). Microbial inoculants: Reviewing the past, discussing the present and previewing an outstanding future for the use of beneficial microorganisms in agriculture. AMB Express, *9*(1), 205. https://doi.org/10.1186/s13568-019-0932-0
- Seefeldt, L. C., Yang, Z.‑Y., Lukoyanov, D. A., Harris, D. F., Dean, D. R., Raugei, S., & Hoffman, B. M. (2020). Reduction of substrates by nitrogenases. Chemical Reviews, *120*(12), 5082–5106. https://doi.org/10.1021/acs.chemrev.9b00556
- Serraj, R., Sinclair, T. R., & Purcell, L. C. (1999). Symbiotic N₂ fixation response to drought. Journal of Experimental Botany, *50*(331), 143–155. https://doi.org/10.1093/jxb/50.331.143
- Streeter, J. G. (1988). Inhibition of legume nodule formation and N₂ fixation by nitrate. CRC Critical Reviews in Plant Sciences, *7*(1), 1–23. https://doi.org/10.1080/07352688809382257
- Sutton, M. A., Oenema, O., Erisman, J. W., Leip, A., van Grinsven, H., & Winiwarter, W. (2011). Too much of a good thing. Nature, 472(7342), 159–161. https://doi.org/10.1038/472159a
- Udvardi, M. K., & Poole, P. S. (2013). Transport and metabolism in legume–rhizobia symbioses. Annual Review of Plant Biology, *64*, 781–805. https://doi.org/10.1146/annurev-arplant-050312-120235
- Vacheron, J., Desbrosses, G., Bouffaud, M.‑L., Touraine, B., Moënne‑Loccoz, Y., Muller, D., Legendre, L., Wisniewski‑Dyé, F., & Prigent‑Combaret, C. (2013). Plant growth‑promoting rhizobacteria and root system functioning. Frontiers in Plant Science, *4*, 356. https://doi.org/10.3389/fpls.2013.00356
- Vance, C. P. (2001). Symbiotic nitrogen fixation and phosphorus acquisition. Plant nutrition in a world of declining renewable resources. Plant Physiology, *127*(2), 390–397. https://doi.org/10.1104/pp.010331
- Vurukonda, S. S. K. P., Vardharajula, S., Shrivastava, M., & SkZ, A. (2016). Enhancement of drought stress tolerance in crops by plant growth promoting rhizobacteria. Microbiological Research, *184*, 13–24. https://doi.org/10.1016/j.micres.2015.12.003
- Wang, D., Yang, S., Tang, F., & Zhu, H. (2012). Symbiosis specificity in the legume–rhizobial mutualism. Cellular Microbiology, *14*(3), 334–342. https://doi.org/10.1111/j.1462-5822.2011.01736.x
- Wolfert, S., Ge, L., Verdouw, C., & Bogaardt, M. J. (2017). Big data in smart farming – A review. Agricultural Systems, *153*, 69–80. https://doi.org/10.1016/j.agsy.2017.01.023
- Zahran, H. H. (1999). Rhizobium-legume symbiosis and nitrogen fixation under severe conditions and in an arid climate. Microbiology and Molecular Biology Reviews, *63*(4), 968–989. https://doi.org/10.1128/MMBR.63.4.968-989.1999
- Zhang, X., Davidson, E. A., Mauzerall, D. L., Searchinger, T. D., Dumas, P., & Shen, Y. (2015). Managing nitrogen for sustainable development. Nature, 528(7580), 51–59. https://doi.org/10.1038/nature15743
- Zhao, J., Chen, J., Beillouin, D., Lambers, H., Yang, Y., Smith, P., Zeng, Z., Olesen, J. E., & Zang, H. (2022). Global systematic review with meta-analysis reveals yield advantage of legume-based rotations and its drivers. Nature Communications, 13, 4926. https://doi.org/10.1038/s41467-022-32464-0

