INFLUÊNCIA DO USO DE HERBICIDAS NO RENDIMENTO E NA QUALIDADE DE SEMENTES DA CULTURA DO ARROZ-VERMELHO

Abstract

Red rice is one of the main dishes of Brazilian Northeastern cuisine, predominantly in the states of Paraíba and Ceará. One of the major factors that influence growth and rice crop productivity are weeds because these unwanted plants compete for light, nutrients and water. This study aims to evaluate the influence of use of herbicides for weed control on yield and quality of red rice seeds. Two herbicides were used, they were DMA and Herbadox, with their respective active ingredients: 2,4-D acid and pendimethalin. The research was conducted on field conditions at Department of Phytotechnology and Environmental Sciences, from Agricultural Science Center, Campus II, from the Federal University of Paraíba (UFPB), located in Areia City – Paraíba. The experiment was divided into 4 blocks with spacing of 1 meter between each one; every block was formed by 10 plots (10 treatments) measuring 4 x 4 m. One hundred fifty seeds were planted per meter with the spacing of 0.5 m. The treatments were arranged in applications of different single dosages of each herbicide described above, associated dosages of the herbicides and treatment without chemical control (control). The factors evaluate were herbicide efficiency on weed control, phytotoxicity, productivity, emergency speed index, emergence speed and weight of a thousand seeds. The red rice of that experiment was grown in a non-irrigated area (rainfed agricultural conditions) and was not used any type of fertilization. The results were submitted to analysis of variance and compared by Dunnett test at 5% of probability, using SAS statistical software program. It was concluded that the weed control, productivity and the emergence speed were influenced by the dosages of the herbicides tested in this experiment; the emergence speed rates linearly decreased with the increase in the herbicide dosages, whether isolated or in associated dosages; phytotoxicity, the emergence speed index and the thousand seeds weighted were not affected by the dosages of the herbicides.