The seeder has dispensing lines (18) with inlet ports (17) and cover devices arranged in a rotating section of a separation drum (2). Flap-like shut-off units are arranged in a region of the inlet ports. The shut-off units are designed as flaps (24) and butterfly valves that are made of a resilient material. The shut-off units comprise two different rigidity regions (27). One of the regions of the shut-off units is stiffer than the other region of the shut-off units. The former region covers the inlet ports, and is made of reinforcement material, resilient and/or flexible material. The latter region is made of flexible material. The shut-off units are made of a resilient material and a rigid insert material e.g. metal insert and fabric insert.