Determinação da tolerância em espécies daninhas rubiáceas ao glyphosate e quantificação de ceras epicuticulares em função da disponibilidade de água no solo

Abstract

Weed species tolerant to herbicides are widely disseminated in all regions of Brazil. The objective of this research was to expand the information about species / weeds biotypes of Rubiaceae family to allow for better understanding of the variation of its tolerance to glyphosate. Populations of weeds rubiaceae (Borreria latifolia and Richardia brasiliensis) were collected in southwestern Paraná and Northern of Santa Catarina. The first study evaluated the response to glyphosate doses in these species / biotypes. The treatments were arranged in a completely randomized design (CRD), in a factorial scheme, where the first factor represented the populations of each species (B. latifolia and R. brasiliensis), and the second factor glyphosate levels (0, 74, 163, 360, 792 and 1742 g e a ha -1). The variables were visual control response at 14 and 28 DAA and mass of green shoots and dried at 28 DAA. The second study was conducted in a greenhouse in DIC for quantification of epicuticular waxes present on the surface of the leaves of the same species. The experiment was arranged in a factorial 6 x 2 with six biotypes, three B. latifolia R. brasiliensis and three who underwent two different irrigation regimes, near the soil field capacity (FC) and near the point permanent wilting (PMP). Was preceded extraction of waxes with solvents and quantification was made by weighing. The data obtained in the experiment were submitted to F test at 5% probability. Variations were found in the control of rubiáceas species. Biotypes that showed greater tolerance factor were 283 and 300. These same biotypes were the most increased deposition of epicuticular waxes under water stress conditions, however, when in field capacity, the quantities of deposited wax showed no differences. Biotypes of R. brasiliensis showed increased tolerance to glyphosate compared to biotypes of B. latifolia.