Interferência do nabo e efeitos de doses de nitrogênio no crescimento e desenvolvimento da cultura da cevada

Abstract

The competition with weeds, mainly turnip (Raphanus raphanistrum L.), results in high losses of productivity in barley (Hordeum vulgare L.), besides the reduction of the quality of the product harvested, considering that nitrogen is one of the most important nutrients for the crop and can compete with weeds. The objective of this study was to evaluate the effects of nitrogen levels applied on barley culture in different populations of turnip. The experiment was conducted in a greenhouse, with a completely randomized experimental design, with four replications. The cultivar of barley used was a BRS Brau, and the experimental units were composed of polyethylene pots with a capacity of 12 dm³, filled with soil as substrate. The treatments were allocated in a 5 x 4 factorial scheme, in which the first factor was composed of different doses of nitrogen (0, 50, 100, 150 and 200 kg ha-1), and the second factor was composed of turnip (0, 4, 8 and 16 plants per pot). The evaluations were; plant height and number of stems per plant at 30, 45, 60 and 75 DAE (days after emergence); total number of stalks per pot, number of stalks / number of spikes, number of stems with spikes and number of stalks without spikes at 90 DAE (time of harvest). After harvesting, the leaf area, length, volume and dry mass of the roots and dry mass of the shoot were measured. Nitrogen favored the growth in height of the barley plants in all the evaluation dates. The increase of the dose of nitrogen applied and the decrease of the density of turnip plants lead to the increase of the number of stems per plant and the greater root development of the barley. The increase of turnip density reduces the development of the aerial part and root of the barley, however, the increase of the dose of nitrogen contributes to the greater development of the crop