Levels of urea fertilizer on germination and vigor of urochloa brizantha cv piatã seeds

The use of high-quality seeds is a premise for the implantation of pasture under sustainable farming systems to livestock production. The usual practice is to mix Urochloa seeds with nitrogenous to use these inputs. The objective of this study was to evaluate the effect of contact time (0, 3, 6, 12, 24, 48, and 72 hours) and amounts (50, 100, and 150 kg N-1) of urea on Urochloa brizantha seeds physiological quality. A completely randomized experimental design was used, with three replicates. Seedling emergence, germination of normal and abnormal seedlings, and dead seeds were evaluated. It was found that after 3 hours of contact, all seeds lose quality. The number of dead seeds presented a significant (p <0.001) and negative correlation (91.7%) for the number of normal seedlings. The mix ratio between urea and seed affects the seed deterioration index, expressing lower seedlings emerged, concerning control treatment. The highest level of urea (150 kg N-1) decreased the emergence index by 23.3% related to the use lowest dose (50 kg N-1). It is concluded that the reduction in viability and vigor begins after 3 hours of contact with fertilizers, so the number of unviable seeds highly increases after 48-hours of contact.