An opener assembly for an agricultural seeder has an opener disc attached to an opener subframe. The opener disc is angled to the direction of travel to create a furrow for depositing seeds. A boot is mounted to the opener subframe beside the opener disc for preventing loose soil from falling into the furrow ahead of seed deposited therein. A seed tube is mounted to the opener subframe by a two-part bracket. The bracket includes a first part attached to the opener subframe and a second part fixed to the seed tube. The first part has a channel structure for receiving and partially surrounding the seed tube, and a pair of slots formed in sidewalls of the channel structure. The second part has an L-shaped structure with a portion that mates with the pair of slots. A key ring mechanism is used to lock the first and second parts together.