During two years, it was evaluated the effects of side-dressing application of nitrogen after weeding made at different growth periods of the bean crop (Phaseolus vulgaris L.) during the winter season. Three cultivars were used in the first year [Novo Jalo (type I), Ouro (type II) and Ouro Negro (type III)] and two in the second year (Ouro and Ouro Negro). Each cultivar constituted one experiment. The treatments consisted of six weeding periods, two side-dressing applications of nitrogen (0 and 30/ha), with ammonium sulphate as source, and two additional treatments. Treatments were arranged in a (6 x 2 ) + 2 factorial randomized block experimental design, with four replications. In The control treatments plus weeding and control treatment without weeding, the nitrogen fertilizer was distributed at V3 stage. Competition against weeds throughout the whole cycle of the cultivars caused a reduction in all primary components of ‘Ouro Negro’ and only for the number grains per pod of ‘Novo Jalo’ and for the weight of 100 grains of ‘Ouro’. Side-dressing application of nitron fertilizer increased grain yield for all three cultivars as well as the number of pods per hectare but the weight of 100 grains did not increase for ‘Novo Jalo’. When side-dressing nitrogen application was done immediately after delaing weeding for 10 days, in relation to the total period of interference prevention, was not able to provide crop yield recovery capacity.
Phaseolus vulgaris; weed; nitrogen
