Effects of a S-metolachlor based herbicide on two plant models: Zea mays L. and Lactuca sativa L

ABSTRACT

Corn is the second most cultivated crop in Brazil, the number-one country in pesticide consumption. Chemical control of weeds is performed using herbicides such as S-metolachlor with pre- and post-emergence action and thus the toxicity of herbicides constitutes a matter of great concern. The present investigation aimed to examine the effects of an S-metolachlor-based herbicide on Lactuca sativa L. (lettuce) and Zea mays L. (maize) utilizing various bioassays. The test solutions were prepared from commercial products containing the active ingredient. Seeds from the plant models were exposed in petri dishes and maintained under biochemical oxygen demand (BOD) at 24°C. Distilled water was negative and aluminium positive control. Macroscopic analyses (germination and growth) were conducted for both plant species, and microscopic analysis (cell cycle and chromosomal alterations) were performed for L. sativa root tip cells. Detrimental interference of S-metolachlor-based herbicide was noted with lettuce for all parameters tested reducing plant germination by over 50% and the germination speed by over 45% and showing a significant decrease in mitotic index, from 16.25% to 9,28% even on the lowest concentration tested. In maize, there was no significant interference in plant germination; however, speed of germination was significantly hampered, reaching a 51.22% reduction for the highest concentration tested. Data demonstrated that the herbicide was toxic as evidenced by its phyto- and cytotoxicity in L. sativa L. and Z. mays L.

GRAPHICAL ABSTRACT

Macroscopic germination bioassay, root and aerial growth was assessed in Lactuca sativa and Zea mays. Cytogenetic assay through cell cycle analysis performed in L. sativa

KEYWORDS:

• Phytotoxicity
• cytogenetics
• micronuclei
• seedling development
• germination
• S-metolachlor
• Lactuca sativa L. (lettuce) and Zea mays L. (maize)

Acknowledgments

To the Coordination for the Improvement of Higher Education Personnel (CAPES) for granting a Doctoral scholarship and to the Federal University of Lavras (UFLA) for granting the Scientific Initiation scholarship to the authors. To Professor João Cândido de Souza, from the Department of Biology (DBI) of the Federal University of Lavras (UFLA), for donating the maize seeds that were used in this research. To professor Adriano Teodoro Brusi, from the Department of Agriculture (DAG) for giving away the herbicides.

Disclosure statement

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

Additional information

Larissa Fonseca Andrade Vieira is a researcher with ten years of experience in phyto-geno-toxic studies and all the experimental designs applied here were derived from a wide range of experiments to find optimal test conditions for studies in this field.

Authors Contribution

A.L.F. concepted and design the work; S.Q.M. organized the experiments, collected the data and drafted the article; P.M.J. analyzed and interpreted the data collected and edited and revised the writing; A.L.F. reviewed and approved the final version of the article.

Data availability statement

The data that support the findings of this study are available from the corresponding author, L.F. Andrade-Vieira, upon reasonable request.

Additional information

Funding

This study was funded by Brazilian funding agency “Coordination for the Improvement of Higher Education Personnel” (CAPES – Coordenação de Aperfeiçoamento de Pessoal de Nível Superior)” as doctoral fellowship.