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

Akbar Padash,Behrooz Esmailpour,Cristina Cruz,Ali Ashraf Soltani Toularoud,Rasoul Azarmi

doi:10.3390/agriculture12020251

Akbar Padash, Behrooz Esmailpour + Show 3 more

Open Access

https://doi.org/10.3390/agriculture12020251

Copy DOI

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.

Highlights

Nitrate is one of the most important forms of nitrogen in agricultural soils
Due to the economic relevance of lettuce, and due to its high consumption as a leafy salad, and the broad use of DCD, this study aimed to investigate the role of mycorrhizal and endophytic fungi (Glomus mosseae, Glomus etunicatum, and P. indica) as possible tools to reduce the phytotoxicity of DCD
Shi et al [25] found that nitrification inhibitor phosphate dimethylpyrazole phosphate (DMPP) inhibited nitrifier-induced denitrification, which is an important source of soil nitrous oxide

Summary

Introduction

The soil nitrate concentration is the balance between the inputs (mainly fertilizer) and the outputs (biological transformations, biological immobilization and transformation, and leaching) where nitrifying microorganisms play a key role. In the soil, these organisms convert ammonium to nitrite and nitrite to nitrate during the nitrification process [1]. Nitrification inhibitors are compounds that delay the bio-oxidation of ammonium to nitrite without affecting the oxidation of nitrite to nitrate [2] This is carried out by preventing or interfering with the metabolism of bacteria that are effective in nitrite generation (such as Nitrosomonas) [3]. The use of triazole compounds such as 1,2,4-Triazole (TZ), when applied in doses between 0.2 and 10 mg L−1, disrupts the nitrification process and can have a negative effect on other bacteria (aerobic and methane-oxidizing heterotrophic bacteria) [7]

Objectives

Methods

Results

Conclusion