Uso de fluxofenim e metcamifen como protetores ao herbicida S-metolachlor em capim Llanero

Abstract

The seed treatment with safeners have been showed a promisor potential to selectivity of some herbicides, representing a viable alternative to be used as graminicide at pastures areas. However, there are few studies showing the safeners efficacy in forage grasses. By this way, the present study, aimed to evaluate the protector effect of fluxofenim and metcamifen to S-metolachlor herbicide in Llanero grass. The experiment was installed at complete random block, four reps and with the treatments adjusted at 2 x 6 x 6 factorial scheme, as following, two safeners (fluxofenim and metcamifen), six doses of safener (0; 20, 40, 80, 160 and 320 mL), all doses referring to 100 kg of seeds, and six doses of S-metolachlor herbicide (0, 750, 1250, 1500, 1750 and 2000 mL ha-1 ), applied at preemergence. The effect of association among different safeners, doses of safener and doses of S-metolachlor was evaluated by visual injury on Llanero grass plants at 7, 14, 21 28, 32 e 42 days after emergency (DAE); by plant height, number of tillers and dry matter accumulated at 42 DAE. The visual injury results were submitted to regression analysis and the freedom degrees of factor evaluated unfold in the polynomial effect. The values of plant height, number of tiller and dry matter accumulation were submitted to analysis of variance and, when significative, the of treatments compared by Scoot-Knott test at 5% of probability. With the obtained results it is possible to affirm that fluxofenim and metcamifen used at seed treatment protect plants of Llanero grass from S-metolachlor herbicide phytotoxic action. The use of fluxofenim or metcamifen both at 320 mL kg-1 of seeds provided higher safener effect to Llanero plants. The metcamifen provided higher safener effect to S-metolachlor herbicide phytotoxic action when comparing with fluxofenim. The use of fluxofenim or metcamifen in the seed treatment provided higher number of tiller production and higher dry matter accumulation of Llanero plants.