Response of soybean cultivars with different maturation times to pre-emergence herbicides

Herbicide selectivity is the basis for chemical control of weeds; however, it depends on the interactions between herbicide, crop, and edaphoclimatic conditions. The objective of this work was to evaluate the selectivity of herbicides applied at the pre-emergence stage of soybean cultivars with different maturation times grown in different locations. The experiment was conducted under field conditions, in two crop seasons (2019/2020 and 2020/2021), in Lages and Curitibanos, state of Santa Catarina, Brazil. A randomized block experimental design was used, with treatments organized in 4×3 (2019/2020) and 4×4 (2020/2021) factorial arrangements, with four replications. The treatments consisted of interactions between four soybean cultivars: BMX Raio IPRO® (Raio), BMX Zeus IPRO® (Zeus), MONSOY 5947 IPRO® (Monsoy), and BMX Fibra IPRO® (Fibra) and three or four herbicide treatments: control with no herbicides, sulfentrazone + diuron, and diclosulam in 2019/2020; and control with no herbicide, sulfentrazone + diuron, diclosulam, and pyroxasulfone + flumioxazin in 2020/2021. The plots were evaluated for phytotoxicity of herbicides, canopy closure, plant height, stand of plants, number of pods per plant, one-thousand grain weight, and grain yield. The phytotoxicity of herbicides on the soybean plants was mild, under 11%, regardless of the cultivar and growth location. The soybean plants fully recovered from the injuries at 14 days after herbicide application. In Curitibanos, the cultivar Zeus presented higher grain yield in both crop seasons. The herbicide factor showed that sulfentrazone + diuron and diclosulam decreased the grain yield of the cultivars Raio and Zeus in 2019/2020. In the following crop season, only the cultivar Raio presented decreases in grain yield due to the application of diclosulam and pyroxasulfone + flumioxazin. In Lages, the soybean cultivar factor affected the grain yield; the cultivars Monsoy and Fibra were the most productive.