Biological activity of metribuzin and linuron on two units of a red latosol originally under cerrado vegetation

Abstract

Aiming to study the biological activity of the metribuzin and linuron a bioassay was carried out under laboratory conditions using a 2 x 2 x 7 factorial. The factors were: two soil units (Dark-red Latosol-heavy clay and Red-Yellow Latosol-sandy loam texture), two herbicides (metribuzin and linuron) and seven rates of the herbicides (0, 72, 144, 216, 288, 360 and 432 g/ha of metribuzin and 0, 200, 400, 600, 800, 1,000 and 1,200 g/ha of linuron). The Dark-Red and Red-Yellow soils contained 65% and 17% of clay, 12% and 3% of silt, 23% and 80% of sand, 2,07% and 2,06% of organic matter and pH of 5,5 and 5,4, respectively. The experimental design was in randomized blocks with 28 treatments and five replications. Cucumis sativus L. cv. Aodai, was the test plant and the experimental plot was a plastic cup with 260 ml of soil with two seedlings in each cup. In the obtained data, no effect from the two soil materials was observed in the biological activity of herbicides. Linuron had low biological activity, possibly duo to the low solubility. There were increasing effects of doses only to metribuzin in the dry biomass, assessed by linear equation; and by cubic equation, in the green biomass and moisture of plants, in both soil materials.