The application of three nitrogen sources in five concentrations each were studied in the physiological quality and yield of snap-bean seeds, cv. Macarrão Trepador Hortivale, from September/2000 to February/2001, in the Centro de Ciências Agrárias of the Universidade Federal of Paraíba, in Areia. A randomized complete block design was used, with treatments distributed in factorial scheme of (3 x 5) + 1, corresponding to nitrogen sources (calcium nitrate, ammonium sulfate and urea) and the second the five N levels (0, 25, 50, 75 and 100 kg.ha-1), and an additional treatment (without fertilization), in four replications. At 100 kg.ha-1 of N, the sources nitrate of calcium and sulfate of ammonium and urea at 55 kg.ha-1 of N presented the highest snap-bean seed yields, 2.571, 3.219 and 2.221 kg.ha-1, respectively, which surpassed the national average by 1.517, 1.219 and 1.221 kg.ha-1. The N in all the sources influenced the germination and the vigor positively (germination speed index and field emergence) of snap-bean seeds. At 68,8 and 49kg.ha-1 of N, calcium nitrate and urea were responsible for the maximum values for germination percentage, 72% and 75%, respectively. For ammonium sulfate there was a linear increase in the germination percentage, as the levels of N increased and at 100 kg.ha-1 of 84% germination was obtained. The germination speed Index showed higher values, 6,0; 7,7 and 6,9 at 49; 71 and 53 kg.ha-1 N, calcium nitrate, urea and ammonium sulfate, respectively. The field emergence increased linearly with calcium nitrate concentrations reaching the maximum emergence (70%) obtained at the 100 kg ha-1 N concentration in each source. The ammonium sulfate should be recommended as a source of N, in snap-bean seed production programs.
Phaseolus vulgaris L.; seeds; fertilization; germination; vigour
