A process and an apparatus continuously treat seeds with ultrasonic transmission. The process includes mixing seeds with a flowable medium to create a flowable slurry of seeds； continuously moving the flowable slurry of seeds for a length of a flow pipe through a helical path within the flow pipe； and as the flowable slurry flows through the helical path within the for the length of the flow pipe, subjecting the seeds to ultrasonic transmission created by ultrasonic transducers arranged along the length of the flow pipe. The seeds in the flowable slurry are subjected to the ultrasonic transmission having such waveforms and being transmitted in a manner so as not to damage the seeds and to produce ultrasonically-treated seeds that have regulated germination characteristics, such that plants resulting from the ultrasonically-treated seeds when the seeds are planted have affected growth characteristics. The apparatus effects this process.
