Reducing an imidazolinone-resistant weedy rice soil seedbank with soybean and Provisia rice system rotations

Background: Provisia rice and glyphosate-resistant soybean can control imidazolinone(IMI)-resistant weedy rice (WR-R) and reduce the soil seedbank. Objective: We evaluated different systems to reduce the WR-R soil seedbank under analysis when adopting soybean and Provisia rice (PV). Methods: From 2017 to 2022, a field experiment in randomized block design with four repetitions was performed. In 2017-2018, WR-R and Clearfield® rice (CL) were sown in the area. From 2018 to 2022, twelve systems [including CL, Provisia (PV), non-CL rice (NCL) and Soy] were used: S1) PV-PV-PV-PV, S2) CL-CL-CL-CL, S3) PV-CL-PV-CL, S4) PV-PV-Soy-CL, S5) PV-PV-CL-CL, S6) PV-Soy-PV-Soy, S7) Soy-PV-PV-Soy, S8) Soy-PV-PV-NCL, S9) PV-PV-PV-NCL, S10) Soy-PV-PV-CL, S11) Soy-Soy-PV-PV, and S12) PV-Soy-PV-CL. The WR-R management were CL – imazapyr + imazapic, PV – quizalofop-p-ethyl, NCL – no specific treatment, and Soy – glyphosate. WR-R plant density and soil seedbank were evaluated during the experiment. The systems were analyzed by year and each system over the years and the means were compared (LSD, p