The present disclosure relates to a seeder, configured to deposit seeds in trays or substrate in a pattern of seed positions, comprising: - a seed supply； - a conveyor configured to transfer seeds from the seed supply, with the seeds organized in the pattern of seed positions defined by seed holding positions of the conveyor, to the trays or substrate and release extracted seeds in the pattern of seed positions into the trays or substrate, - at least one detector comprising at least a light source, such as a light beam and/or an array of LED's, and a sensor, such as at least one camera and/or a line scanner, and configured to detect seeds at seed holding positions of the conveyor in transfer from the seed supply to the trays or substrate and generate a signal, wherein the light source is obliquely oriented at seed holding positions of the conveyor, relative to a surface of the conveyor, to generate grazing light on or over the conveyor, for seeds to cast detectable shadows on the surface of the conveyor, and the sensor is oriented at the surface of the conveyor to detect shadows on the conveyor, cast by seeds at seed holding positions. Also the disclosure relates to an associated method and a computer-readable storage medium to carry a program for carrying out the method.La présente invention concerne un semoir configuré pour déposer des graines dans des plateaux ou du substrat selon un motif de positions de graines, lequel comprend : - une alimentation en graines ； - un transporteur configuré pour transférer des graines depuis l'alimentation en graines, les graines étant organisées selon le motif de positions de graines définies par des positions de maintien de graines du transporteur, vers les plateaux ou le substrat et libérer les graines extraites selon le motif de positions de graines dans les plateaux ou le substrat, - au moins un détecteur comprenant au moins une source de lumière telle qu'un faisceau de lumière et/ou un réseau de DEL, et un capteur tel qu'au
