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The objective of this study was to evaluate the effectiveness of synthetic auxins in the control of Conyza sumatrensis in mixtures for use in the first application, and the effectiveness of burndown herbicides alone or in mixtures for use in the second application, in soybean pre-sowing. Experiment 1 consisted of auxin herbicides (fluroxypyr or dicamba) in mixtures with herbicides (glyphosate, glufosinate, saflufenacil, carfentrazone, and chlorimuron) used for the first application in pre-sowing. Experiment 2 consisted of burndown herbicides (diquat, glufosinate, glyphosate, chlorimuron, saflufenacil, and carfentrazone), alone or at mixtures, used for sequential application in pre-sowing. For the first application, the effectiveness of glyphosate + dicamba or fluroxypyr was low and must be complemented by the addition of a PPO-inhibiting herbicide, mainly saflufenacil. The mixture of glufosinate, instead of glyphosate, with synthetic auxin was more effective, even increasing with the addition of saflufenacil. For the second application, with burndown herbicides, glufosinate was superior and effective when mixed with saflufenacil. For the first application in soybean pre-sowing, glyphosate or glufosinate + synthetic auxin + saflufenacil are effective for the control of C. sumatrensis. For the second application, glufosinate at mixtures is effective in controlling C. sumatrensis. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the production components of soybean and the physiological quality of seeds according to the application of subdoses of herbicides at the reproductive stage of healthy plants. The treatments consisted of the application of glyphosate (122.5 g acid equivalent [ae] ha-1), chlorimuron (1.75 g active ingredient [ai] ha-1), 2,4-D (134 g ae ha-1), fomesafen (60 g ai ha-1), glufosinate (55 g ai ha-1), paraquat (35 g ai ha-1), and control (no application). The chlorophyll index, agronomic performance, and physiological quality of seeds were evaluated. Glyphosate, chlorimuron, fomesafen, or glufosinate resulted in an increase in soybean plant height. Chlorimuron increased yield compared to the control. Paraquat or glufosinate, despite the injury, did not reduce yield, but the application of these herbicides is not recommended to stimulate plant development, given the potential for injury. The 2,4-D was the only one that caused a reduction in the physiological quality of soybean seeds. [ABSTRACT FROM AUTHOR]

The production of soybean seeds is increasingly becoming a growing and demanding market. And quality is a crucial factor to be considered, which will depend on the crop and physiological maturity of the seed. The objective of this study was to determine the best phenological stage at the end of the soybean crop cycle to perform the desiccation so as to improve the physiological quality of seeds without affecting grain yields. The experiment was conducted under field conditions in the 2016/2017 harvest. Two drying agents - diquat and glufosinate (ammonium salt) - were applied at the R6 and R6.5 and R7.2 growth stages, in addition to R9. An experimental design was used with completely randomized blocks, subdivided in plots (4 x 2). The phenological stages (R6 and R6.5, R7.2 and R9 - control) were assigned to the main plot and the drying agents to the subplots. Germination, vigor, weight of 1000 grains, grain yield and harvest anticipation were evaluated. The use of the drying agents in conjunction with the phenological stages of implementation allowed for the anticipation of harvest by 4 to 13 days, reduced yield and weight of 1000 grains, when applied in R6 and R6.5. Both drying agents had a negative influence on both the germination and vigor of seeds, with glufosinate being the drying agent with the worst germination and vigor indicators. Its use for desiccation is therefore not recommended so as not to affect the physiological quality of soybean seeds. [ABSTRACT FROM AUTHOR]