Interferência e nível de dano econômico de nabo em cultivares de cevada

Abstract

At the present time one of the main obstacles of the barley culture is the lack of registered herbicides for weed management. For this reason, the use of tools that minimize the losses caused by weed interference becomes important. The objective of this work was to evaluate the interference and level of economic damage (NDE) of the turnip in competition with barley, estimated as a function of variations in the competing populations and cultivars of the crop. The treatments consisted of barley cultivars (BRS Swabia, ANA 01, BRS Korbel, BRS Manduri, BRS Cauê and BRS Greta) and populations of turnip plants (0 to 948 plants m-2) for each cultivar tested, respectively. The variables plant population, leaf area, soil cover and dry mass of the turnip plants were evaluated for the calculation of yield losses of barley in the presence of weed. The control cost (herbicide and tratorized terrestrial application, in dollars ha-1), grain yield of barley (kg ha-1), barley price (kg-1 grains), herbicide efficiency) and the population of turnip plants were used to calculate the level of economic damage of the weed on the crop. The cover of the turnip soil presents better adjustment to the model of the rectangular hyperbola, and the grain yield losses, due to the interference of the weed satisfactorily estimated by this model. The cultivars BRS Greta, BRS Swabia, Ana 01 and BRS Manduri in the average of all the evaluated variables were the most competitive ones in the presence of the turnip and also those that increase the level of economic damage, justifying the use of management measures of turnip in the highest populations. The increase in grain yield, barley price, herbicide efficiency and reduction in control costs reduce the level of economic damage, justifying the adoption of control measures at low turnip densities. Turnip is shown to be competitive in the barley crop, requiring at least 0.83 m-2 plant for control to be justified.