An experiment was carried out at Embrapa Soja, in Londrina-PR, Brazil to determine the relationships between imbibition periods, water absorption levels and seed germination of the weed hairy beggartick (Bidens pilosa). Seeds were harvested from field plants in March 1997, and were set to imbibe for periods of 06, 12, 18, 24 and 48 hours. The water content of the seeds and the electric conductivity of their exudates were determined. Germination was also determined using a germinator set for cycles of 14/10 hours of diffuse fluorescent light and dark, respectively, at 30º/20 ºC respective temperatures, and 90±5% constant relative humididty (RH). A completely randomized design experiment, with four replications of 100 seeds each, was used. Average seed germination percentage was 87.5%. Water absorption had a significant increase with longer imbibition periods. No correlation was observed among germination, water imbibition periods and electric conductivity. Water absorption capacity and electric conductivity presented a medium degree of correlation. Germination started on the third day and the peak was reached on the fifth day. The highest germination velocity index was obtained with the highest periods of seed imbibition.
electric conductivity; water absorption; weed
