Residual effect of herbicides on soya, peanuts and crotalaria and its toxicity in non-target organisms

• Grant number: 21/05328-0
• Support Opportunities: Scholarships in Brazil - Master
• Start date: March 01, 2022
• End date: December 31, 2023
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Patrícia Andrea Monquero
• Grantee: Bruna Ferrari Schedenffeldt
• Host Institution: Centro de Ciências Agrárias (CCA). Universidade Federal de São Carlos (UFSCAR). Araras , SP, Brazil

Abstract

The use of herbicides with a long residual can influence the productivity of agricultural crops and terrestrial and aquatic ecosystems. Thus, the objective of the work is to evaluate the residual effect of the dose-response of the herbicides indaziflam, sulfentrazone and clomazone on the growth and development of soybeans, peanuts and crotalaria and their acute (CL50) and chronic (CENO and CEO) effects in Lemna minor and Eisenia fetida. The experiment will be divided into three parts, in which the first part will be carried out in a greenhouse following a completely randomized experimental design (DIC) for each crop (soybean, peanut and crotalaria) and herbicide (indaziflam, sulfentrazone and clomazone) in 6 x 5 factorial scheme, with five replications, with 5 doses of the herbicides (0, 1 / 16D, 1 / 8D, 1 / 4D, 1 / 2D and 1D) and 5 sowing periods of the crops (0, 10, 20, 40 and 60 days after application). The plants will be evaluated for phytotoxicity, height, number of leaves and chlorophyll content in the leaves (chlorofiLOG) at 7, 14, 21, 28, 35.42 and 49 days after the germination of the control. At 49 days the plants will be cut close to the ground to obtain the dry biomass of the aerial part. In the end, the data obtained for each herbicide will be subjected to analysis of variance by the F test, and the means will be compared using the Scott-Knott test at 5% significance and for the data referring to biomass, the reduction of the dry biomass in percentage (%) in relation to the control (without herbicide application). For the second part of the work, laboratory tests will be conducted, according to the OECD (2002) standards, of chronic toxicity (CL50; 7d; CENO and CEO) to analyze the effect of the same herbicides in different concentrations, according to the ecotoxicological table of USEPA (2017), in the cultivation of Lemna minor, and thus assess mortality, plant size (cm), leaf size (cm), root size (cm) and fresh weight (g) for a period of 7 days . And the last part of the work will also be conducted in the laboratory, according to the ABNT standards (2014), to evaluate the acute (CL50) and chronic effects of different concentrations of the herbicides in Eisenia fetida. This part will last for 14 days (acute) and 56 days (chronic). At the end of the work carried out in the laboratory, the data obtained regarding the acute tests will be evaluated the concentration that caused mortality (E. fetida and L. minor) to 50% of the organisms, which corresponds to the average lethal concentration (LC50), for later calculate and compare with the average value presented in the laboratory control chart (ABNT 2016). The LC50 will be calculated using the statistical method of Trimmed Spearman-Karber (p <0.05), with the aid of the computer program Trimmed Spearman-Karber Method Version 1.5. And the data from the chronic toxicity tests (CEO and CENO) will be submitted to the analysis of normality (Chi-Square test) and homogeneity of variances (Bartlett test) and then the analysis of variance, with the Dunnett test for check for differences between treatments. (AU)