THE ORIGIN OF VARIATION IN SEED DENSITY IN CELERY (APIUM-GRAVEOLENS L)

Seeds were harvested separately from the sequentially formed umbels to obtain information about the origin of variation in seed density in c elery. The study involved seeds from the lowest order (primary) to the highest order (quarternary) umbels from the cvs Mars, Monarch, Selfir a and Tall Utah. With increasing umbel order the percentage germinatio n decreased and the mean germination time increased. Seed density incr eased with increasing umbel order, but was more highly correlated with the length of the seed ripening period which differed for each umbel order due to simultaneous harvesting. The decrease in seed density dur ing seed development was correlated with an increase, in air volume in the seeds. It is concluded that the variation in seed density in cele ry seed lots originated from differences in seed maturity.