Effect of microorganism on behaviour of two commonly used herbicides in wheat/soil system

Abstract Herbicides constitute one of the major problems in the environment mainly because of their ability to entering into plant and microorganisms metabolic pathways. The aim of the study was to give an insight into behaviour of selected herbicides: MCPA and sulfosulfuron in soil/plants after Bacillus cereus and Pseudomonas fluorescens application. The single first-order degradation model (SFO) was used to simulate the decrease of residual mass of herbicides in the soil/wheat system with/without bacteria using LC-MS/MS. The greatest loss of MCPA concentration was noticed in soil enriched with B. cereus (99.7%) on 31st day from application, while the highest decrease of sulfosulfuron was determined in soil enriched with P. fluorescens (97%) on 46th day from application. In wheat, the greatest pesticides loss (98%–99.8%) was noticed on 31st day from application, without bacteria addition. The study presents the influence of pesticides on enzyme in soil, where the higher average dehydrogenase activity was observed for combination with B. cereus approx. 150% as compared to the control. Moreover, pesticides impact on catalase, superoxide dismutase and NADH peroxidase activity, level of lipid peroxidation, thiol content in plants was determined. Increased reactive oxygen species production caused an oxidation of thiol groups and lipid peroxidation. The obtained results indicated that the use of B. cereus and P. fluorescens may reduce harmful effects of stress caused by herbicides. The presented study is the first step in the analysis of chemical and biological properties changes in the soil/wheat system after the application of herbicides and microorganisms.