Weed Control J 2021; 20: e202100723

Research Article

Detection of bioavailable residue of S-metolachlor in the soil by bioassay method

DOI: 10.7824/wcj.2021;20:00723

Abstract

Background

The selection of bioindicator plants can help in the determination of herbicide residues in the soil.

Objective

To analyze the levels of injuries and biomass reduction in bioindicator plants in the presence of S-metolachlor residue in the soil.

Methods

Four potential bioindicator species were evaluated: cucumber (Cucumis sativus), radish (Raphanus sativus), sorghum (Sorghum bicolor) and zucchini (Cucurbita pepo), in six doses of S-metolachlor (0, 180.5, 360, 720, 1440, and 2880 g ha-1). The plants were evaluated, 21 days after emergence (DAE), regarding the levels of injury and percentage of shoot dry matter biomass in relation to the control treatment, without herbicide application.

Results

C. sativus behaved as an extremely sensitive species, with a 100% reduction in dry matter from recommended half dose (1440 g ha-1) of herbicide, and it was the only species that had >80% control compared to other bioindicator plants. S. bicolor was the species that presented the lowest dose value to reduce its growth, needing only 5% of the recommended dose to reduce its growth by 80% and reaching 50% of control with a dose of approximately 14% of recommended dose. The species R. sativus and C. pepo, do not present potential as bioindicator plants due to the high tolerance to herbicide.

Conclusions

C. sativus and S. bicolor showed higher potential for use as bioindicator plants in behavioral studies in soil contaminated with bioavailable residue of S-metolachlor and/or for producers to perform rapid tests with bioassays analyzing the carryover of this herbicide in the soil.