Abstract: 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<0.05). Results: Over the years, no WR-R plant escapes (100% control) were observed in the systems using soybean or PV. However, even after three years of using alternative systems, the return of CL rice allowed seedbank replenishment. Thus, our results suggest that it takes more than four years to deplete the seedbank. The systems in which soybean (S6, S7, and S11) were used for two years were more efficient for soil seedbank reduction. Conclusions: Systems alternating soybean and Provisia rice for more than four years are a strategy to reduce imidazolinone-resistant weedy rice soil seedbanks. Abstract Background glyphosateresistant glyphosate resistant imidazolinoneIMIresistant imidazolinone IMI WRR WR R (WR-R Objective . (PV) Methods 201 2022 performed 20172018, 20172018 2018, 2017-2018 Clearfield (CL area including PV, , nonCL non (NCL S1 S PVPVPVPV, PVPVPVPV PV-PV-PV-PV S2 CLCLCLCL, CLCLCLCL CL-CL-CL-CL S3 PVCLPVCL, PVCLPVCL PV-CL-PV-CL S4 PVPVSoyCL, PVPVSoyCL PV-PV-Soy-CL S5 PVPVCLCL, PVPVCLCL PV-PV-CL-CL S6 PVSoyPVSoy, PVSoyPVSoy Soy, PV-Soy-PV-Soy S7 SoyPVPVSoy, SoyPVPVSoy Soy-PV-PV-Soy S8 SoyPVPVNCL, SoyPVPVNCL NCL, Soy-PV-PV-NCL S9 PVPVPVNCL, PVPVPVNCL PV-PV-PV-NCL S10 SoyPVPVCL, SoyPVPVCL Soy-PV-PV-CL S11 SoySoyPVPV, SoySoyPVPV Soy-Soy-PV-PV S12 PVSoyPVCL. PVSoyPVCL CL. PV-Soy-PV-CL imazapic quizalofoppethyl, quizalofoppethyl quizalofop p ethyl, ethyl quizalofop-p-ethyl treatment LSD, LSD (LSD p<0.05. p005 p<0.05 0 05 p<0.05) Results 100% 100 (100 However replenishment Thus S6, (S6 reduction Conclusions imidazolinoneresistant seedbanks (PV 20 202 2017201 2017-201 p00 p<0.0 10 (10 (S 2 201720 2017-20 p0 p<0. 1 (1 20172 2017-2 p<0 ( 2017- p<

RESUMO: A produtividade do arroz no Sul do Brasil aumentou linearmente ao longo dos anos. A semeadura no início da janela é o principal contribuinte para o aumento da produtividade do arroz no sul do Brasil. No entanto, essa prática pode expor as plântulas de arroz ao estresse por baixa temperatura, aumentando os danos do herbicida e reduzindo a produtividade do arroz. Este trabalho teve como objetivo avaliar o efeito de épocas de semeadura na seletividade de herbicidas em caracteres agronômicos do arroz. Conduzimos experimentos de campo durante as safras 2010/11 e 2011/12 em Capão do Leão, RS, Brasil. O delineamento experimental foi em blocos casualizados completos com arranjo fatorial. O fator A foram a semeadura-precoce (em setembro) e a semeadura-tardia (em novembro); o fator B foram os tratamentos com herbicidas (bispyribac-sodium, cyhalofop-butyl, penoxsulam, metsulfuron-methyl e controle - sem herbicida). A resposta do arroz aos tratamentos com herbicidas diferiu entre os anos. Em 2010/11, o bispyribac-sodium, o penoxsulam e o metsulfuron-methyl prejudicaram o arroz apenas na semeadura-precoce. Em ambos os anos, a semeadura precoce do arroz promoveu maior potencial de rendimento, apesar dos danos dos herbicidas. As injúrias causadas pelos herbicidas bispyribac-sodium, penoxsulam e metsulfuron-methyl foram transitórias, não acarretando em perdas de produtividade. A temperatura fria próxima a aplicação aumenta a injúria dos herbicidas ALS.

ABSTRACT: Rice yield in Southern Brazil has increased linearly over the years. Early season sowing is the primary contributor to rice yield increase in Southern Brazil. However, that practice might expose rice seedlings to the risk of low-temperature stress, which can enhance herbicide injury and reduce rice yield. This research evaluated the effect of sowing dates on herbicide selectivity and agronomical rice traits. We conducted field experiments during the 2010/11 and 2011/12 growing seasons in Capão do Leão, RS, Brazil. The experimental design was a complete randomized block with a factorial arrangement. Factor A was early-sowed (in September) and late-sowed (in November); factor B was herbicide treatment (bispyribac-sodium, cyhalofop-butyl penoxsulam, metsulfuron-methyl, and nontreated check). Rice response to herbicide treatments differed between years. In 2010/11, bispyribac-sodium, penoxsulam, and metsulfuron-methyl injured rice only on early-sowed. In both years, early sowing rice promoted higher yield potential despite herbicide injury. The injury caused by the herbicides bispyribac-sodium, penoxsulam and metsulfurom-methyl was transient did not lead to yield losses. Cold temperature close the application increases the injury of ALS herbicides.

Abstract Background: Soybean cultivation has been an option used to diversify the production system and perform herbicide rotation in irrigated rice crops in the lowland soils of the Rio Grande do Sul State, southern Brazil. However, elevated salinity levels have been detected in these soils that can inhibit plant growth due to the reduction of the osmotic potential of the soil solution and can causes toxicity. The combination of stress factors in the plantation areas can intensify deleterious effects, such as changes in salinity associated with herbicides that trigger oxidative stress in crops. Objective: This study aimed to evaluate osmotic potential, cell damage, and enzyme activities of the antioxidant metabolism on soybean after treatment with herbicides and salinity stress conditions. Methods: For this purpose, completely randomized design was used in a factorial scheme with three replicates. The A factor included four herbicide treatments, as follows: control (no herbicide), sulfentrazone, S-metolachlor, and sulfentrazone + S-metolachlor. The B factor was represented by the following three salinity levels: 0 (control), 60, and 120 mM NaCl, which were applied 24 hours after soybean sowing. Results: The results showed a significant alteration in the osmotic potential of soybean plants, mainly at higher salt concentrations. Although an increase in the lipid peroxidation has been detected in some treatments, antioxidant enzyme action combined with osmotic adjustment to reduce oxidative damage were mechanisms found to be employed by plants to reduce hydrogen peroxide levels. Conclusions: We concluded that herbicide treatment, in combination with saline stress, can alter physiological and biochemical processes of soybean plants.