Luciel Rauni Dezordi

Controle de Brachiaria decumbens Stapf com adição de ureia à calda do glifosato

The addition of nitrogen sources to herbicide spray solution s has been related to improvements in phytosanitary treatments. This study aimed at evaluating the control of Brachiaria decumbens with urea added to the glyphosate spray solution. Treatments consisted of a combination of glyphosate (0.0 g ha -1 , 360.0 g ha -1 , 720.0 g ha -1 and 1,080.0 g ha -1 of the a.i.) and urea doses (0.0 g L -1 , 7.5 g L -1 , 15.0 g L -1 and 25.0 g L -1 of the spray solution), and a control with no application, in a randomized blocks design, in a 4x4 factorial scheme, with three replications. Applications were carried out with the aid of a CO 2 constant pressure sprayer, equipped with a bar for two flat jet nozzles, operating at the pressure of 300.0 kPa. Densities and coverage percentages of plants leaves, provided by the jet nozzles drops, were evaluated, as well as the instantaneous gas exchanges, at 12 a.m., at 2, 4, 6 and 11 days after application (DAA), by using a portable infrared gas analyzer. Visual evaluations of control percentage were carried out at 7, 14, 21 and 28 DAA. No difference was observed in the density and coverage of leaves, for the different urea concentrations. The addition of urea to the glyphosate spray solution improved the B. decumbens control, regardless the herbicide dose, up to the 25.0 g L -1 spray solution concentration. The gas exchange of B. decumbens was lower after 6 DAA, in treatments with higher concentrations of urea in the herbicide spray solution, resulting in a higher control level for these treatments.

Early foliar diagnosis of carrot by univariate methods

ABSTRACT Foliar diagnosis enables early identification of nutritional needs. Objectives of this study were to determine diagnostic indexes by univariate methods: critical level (CL), sufficiency range (SR) and Kenworth Balanced Indexes (IBK) in three phenological stages of carrot in order to interpret results of foliar analysis and verify if limitations of end cycle can be diagnosed at the beginning of the cycle. A database was obtained from leaf sampling, root productivity, and leaf contents of macronutrients and boron (B), copper (Cu), manganese (Mn), and zinc (Zn). Critical levels were determined by linear mathematical models. Order of limitation was generated according to the optimum range of the foliar contents in the SR and IBK. The most limiting nutrients in the region for carrot were Mg, Mn, and N by SR and Cu, Mn, and Zn by IBK. There was no concordance between methods; however, it is possible to anticipate foliar diagnosis for the most limiting nutrients within each method.