The Potential of Cold Plasma-Based Seed Treatments in Legume–Rhizobia Symbiotic Nitrogen Fixation: A Review

The use of cold plasma (CP) seed treatment is an emerging agricultural technology that exhibits the potential to enhance nodulation and symbiotic nitrogen fixation (SNF) in legumes. CP is composed of a diverse mixture of excited atoms, molecules, ions, and radicals that have the potential to affect the physical properties of the seed and influence gene expressions that could have a lasting impact on the nodulation, SNF, growth, and yield of legumes. The direct participation of the CP in the nodulation process and its correlation with the escalation of nodules and SNF is still not fully understood. This review discussed four areas in the nodulation and SNF process that can directly or indirectly affect CP seed treatments: root–rhizobia signal exchange pathways, root/shoot growth and development, phytohormone production, and the nitrogen fixation process. We also discuss the potential challenges and future research requirements associated with plasma technology to enhance SNF in legumes.