It was evaluated 100 breeding lines of common bean in the presence and absence of N in cover in four conditions aiming at identifing the lines of beans which would be tolerant to nitrogen (N) stress and/or also responsive to this nutrient. In each condition there were two distinct experiments with and without N, in a 10 x 10 triple lattice design, being the plot constituted by a line with three meters of length. It was estimated the index of efficiency of nitrogen utilization, through the average grains yield. The obtained yield with N was 12% above the one without N, in the average of the four conditions. By decomposing the effect of levels for each line, in 77% of them there was no answer to the nitrogen fertilization in cover. This, only 22 lines positively responded to nitrogen fertilization and among them the efficiency of N utilization ranged from 11.3 to 18.3kg of grains per kg of applied N.
nitrogen use efficiency; improvement; genetic; Phaseolus vulgaris L.
