A unique seed disk for use in a vacuum type agricultural planter is particularly suited for planting of canola seed. Seed apertures extend through the disk in the thickness direction from the vacuum-side face thereof to the opposing seed-side face thereof, and are each circular in cross-sectional shape. Each apertures features a cylindrical end portion opening through the vacuum-side face of the disk body, a first frustoconical portion whose wider end communicates with the cylindrical end portion, an intermediate cylindrical portion communicating with the narrower end of the first frustoconical portion, and a second frustoconical portion having a narrower end that communicates with the intermediate cylindrical portion and an opposing wider end that opens through the seed-side face of the disk body. A preferred embodiment features ninety seed apertures in the disk, and an accompanying twelve prong knockout wheel for dislodging debris individually from the seed apertures.
