Uso de fluxofenim como protetor ao herbicida S-metolachlor em capim Massai

Abstract

The seed treatments with safeners have been presented promissor potential in the selectivity of some herbicides, representing a viable alternative to use the graminicide herbicides in pasture areas. However, exist only few studies about efficacy of safeners involving forage grasses. Thus, tow studies were conduted in order to evaluate the selectitivy and protector effect of fluxofenim when used in the coating of massai grass seeds. The first trial was installed in laboratory conditions, being conduced with four reps of 50 seeds by plastic transparent boxes in six treatments, as following: seed without coating (untreated); fluxofenim at 20, 40 80, 160 and 320 mL, all rates referent to 100 kg-1 of seed. The protector effect os rates was evaluated by percentage germinated seeds (G), index of speed gemination (IVG), initial time (TI), medium time (TM) and final time (TF) of germination, synchrony of gemination (S) and relative frequency of germination during a period of 13 days in wich endured the geminations. The values os G, IVG, TI, TM, TF, and S were submitted to variance analysis by Test F and when significant, the meas compared by Scott-Knott test at 5% of probability. The relative frequency of germinations results was analyzed according to unimodality or polymodality of each polygon graphically plotted by Origin 8.5.1 SR1 program. The second trial was installed in the complet randon blocks, with four reps, and the treatments located at 6 x 6 factorial squeme, being six rates of fluxofenim (0, 20, 40, 80, 160 and 320 mL, all rates referent to 100 kg-1 of seed and six rates of S-metolachlor herbicide (0, 750, 1250, 1500, 1750 and 2000 mL ha-1 ), all applied at pre-emergence. The effects of association between fluxofenim and S-metolachlor were evaluated by plant height and dry matter production at 42 days after seedling emergence, variables that submitted to variance analysis by Test F and when significant, the meas compared by Scott-Knott test at 5% of probability. According to obtained results, it is possível to affirm that fluxofenim used at 20, 40, 80, 160 and 320 mL 100 kg-1 of seeds provide increases in plant height of massai forage. The rates of 20, 40, 80, 160 and 320 mL 100 kg-1 of fluxofenim provide increases in the dry matter production of Massai plants. The 20, 40, 80, 160 and 320 mL 100 kg-1 of safener fluxofenim provide protection to Massai forage whe submitted to rates of 750, 1250, 1500, 1750 and 2000 mL ha-1 of S-metolachlor applied at pre-emergence.