Phytotoxicity of 2,4-D and fipronil mixtures to three green manure species

Abstract

Sugarcane expansion has been associated with soil contamination by agrochemicals. Pesticides can affect plant growth, and their mixture might have potentiated effects on exposed species. This research aimed to evaluate the influence of fipronil on the phytotoxicity of 2,4-D on three green manure plant species: Canavalia ensiformis, Dolichos lablab, and Lupinus albus. Plants were exposed (for 21 days, at 25 °C) to a control soil and five concentrations of each pesticide and their combinations (36 treatments, considering a full-factorial approach). Effect concentrations of 50% growth inhibition (EC₅₀) were estimated. No phytotoxicity effects were identified when plants were exposed to different fipronil concentrations (up to 0.12 mg kg⁻¹). All species exposed to 2,4-D showed a decrease in shoot and root length and fresh/dry biomass. L. albus and D. lablab roots showed the highest sensitivity when exposed to 2,4-D among the endpoints (EC₅₀ = 0.02 and 0.05 mg kg⁻¹, respectively), while C. ensiformis roots were the most tolerant (EC₅₀ = 0.98 mg kg⁻¹). However, the interference of fipronil on the toxicity of 2,4-D was not detected in different mixture proportions, indicating no interaction between pesticides. Residues of 2,4-D might also impair other crops’ growth, compromise productivity, and limit phytotechnologies for soil recovery.

Keywords:

• Ecotoxicology
• growth inhibition
• pesticides
• soil contamination
• sugarcane cultivation

Author contributions

Allan Pretti Ogura: Conceptualization, Methodology, Formal analysis, Investigation, Writing – Original draft, Supervision, Resources, Project administration; Jacqueline Zanin Lima: Methodology; Investigation; Writing – Reviewing and Editing; Laís Conceição Menezes da Silva: Investigation; Writing – Reviewing and Editing; Mariana Amaral Dias: Investigation, Writing – Reviewing and Editing; Valéria Guimarães Silvestre Rodrigues: Writing – Reviewing and Editing, Resources; Cassiana Carolina Montagner: Methodology, Resources, Funding acquisition; Evaldo Luiz Gaeta Espíndola: Writing – Reviewing and Editing, Supervision, Resources, Funding acquisition.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author, A.P.O., upon reasonable request.

Additional information

Funding

This work was supported by the São Paulo Research Foundation (FAPESP) Process 2015/18790-3; A.P.O. has a postdoctoral scholarship from FAPESP [Process 2021/14789-1] and had a Ph.D. scholarship from the National Council for Scientific and Technological Development (CNPq) Process 140411/2018-6; J.Z.L. had a FAPESP scholarship [Process 2017/16961–0]; L.C.M.S. had a Ph.D. scholarship from CNPq, and M.A.D. has a Ph.D. scholarship from the Coordination of Superior Level Staff Improvement (CAPES).