Use of Symbiotic Fungi to Reduce the Phytotoxic Effect of DCD Nitrification Inhibitors in Lettuce

Abstract

Nitrification inhibitors are commonly used to prevent nitrate leaching. However, the use of nitrification inhibitors is not free of side-effects. Some may be absorbed by the plant and cause phytotoxicity or even affect the food chain. Therefore, a solution that limits the absorption of nitrification inhibitors and its accumulation by the plant may mitigate health and environmental issues potentially associated with high levels of nitrification inhibitors. This solution may relay in the modulation of the plant’s metabolism through the interaction with specific fungal partners. This work tested the hypothesis that the symbiotic interaction between fungi and plant roots can reduce the destructive effects of the nitrification inhibitor Dicyandiamide (DCD) in plants by reducing the uptake of nitrification inhibitors. A greenhouse experiment was conducted, using a complete randomized block design, to test the effect of symbiotic fungi (plants inoculated with Piriformospora indica, Glomus etunicatum, and Glomus mosseae and noninoculated) on the phytotoxicity of DCD applied at four concentrations (0, 5, 50, and 100 mg kg−1 soil). Latuca sativa, cultivar Siyahoo, was selected for this experiment due to its economic value all over the world. The use of high DCD concentrations (100 mg kg−1 soil) affected the leaf chlorophyll content and plant growth in a manner that was significantly mitigated by the symbiosis of the plant with the fungal partner. These results highlight the benefits of using symbiotic fungal inoculants as plant protectors against the phytotoxic effects of DCD.