SEED BANK AND OTHER DEMOGRAPHIC PARAMETERS OF BROOMRAPE (OROBANCHE-CRENATA FORSK) POPULATIONS IN FABA BEAN (VICIA-FABA L)

A study on the population dynamics of broomrape (Orobanche crenata Forskal) in faba bean (Vicia faba L.) was conducted in two locations for 8 years. The 0. crenata seed bank increased every year in the 20-cm depth arable layer until it reached approximately 4 million (M) seeds m-2. Seed viability ranged between 53% and 68%, approximately half of the seeds remaining dormant. About 3x10(-3)% of the seed bank became attached to the root system of the faba beans. Only 9% of the attached broomrapes developed and emerged from the soil, possibly reflecting high levels of intraspecific competition. Maximum broomrape seed production for a population of 53 emerged broomrapes per m2 was approximately 4 M seeds m-2. About 43% of the seeds produced were not incorporated into the soil, most probably as a result of their degradation, decomposition or dispersion.