Herbicides effects on symbiotic nitrogen-fixing bacteria

Rhizobia are an important component of sustainable agricultural production. In symbiosis with legumes, they provide adequate amounts of nitrogen for their growth and leave nitrogen in the soil for crops that follow in the rotation. One of the major threats to symbiotic nitrogen fixation are herbicides. The effect of herbicides on symbiotic nitrogen fixation can be positive or negative. The positive effect is manifested in the stimulation of growth and development of rhizobia. When symbiosis is negatively affected, the efficiency of nitrogen fixation is reduced, resulting in lower legume growth and yield. Herbicides can contact rhizobia immediately after application or, in the case of persistent herbicides, later in the growing season. Herbicides may affect the rhizobia, the host plant, or the establishment and development of the symbiosis. This paper reviews previous research on the effects of herbicides on rhizobia.