2.3.3 Seeds height Seeds height refers to the height between the lowest point of the seed box and the top surface of tubers. It reflects the number of tubers inside the seed box. Low seeds height implies small number of tubers inside the seed box. The suction time, namely the contact time between the nozzle and tuber, was shortened. It made the missing-seeding index increased. An excessive seeds height will extend the suction time, which makes the multiple-seeding index, the starting resistance and the device’s rotation resistance are added.