Lotes de azevém submetidos à doses e épocas de aplicação de glifosato

Abstract

Ryegrass is a forage grass in southern Brazil, but is considered a weed in annual crops. For its desiccation is used on a large scale or the active ingredient glyphosate, continuous use has caused problems of resistance of biotypes to molecules. Thus, the objective was to verify the response of several annual lots (Lolium multiflorum Lam.) Collected in properties of the municipalities of Itaqui, Maçambara and São Borja - RS regarding the susceptibility of glyphosate doses and application times. Ten seed samples were collected and sown in circular containers, where when reaching the 3-4 leaf stage, a recommended dose of glyphosate was applied. After 15 days from the application, select three batches to evaluate the effect of different doses and times. These lots were sown in 250 ml plastic cups filled with commercial Tecnomax® substrate and applied at doses of 180, 360, 720, 1140 and 2280 g e.a.ha-¹ at 40 and 50 days after seedling discontinuation. An evaluation was made by the water loss index (%) applied by the difference in green matter and dry weight, 30 days after each application of the product. The obtained data allow to conclude that the time of application of the product is determinant in the control of the plants, as well as a dose to be applied. Because these factors depend on the biotype and which product will be applied, each biotype has a different product tolerance level.