Influence of peripheral speed of vacuum plates on seed spacing in popcorn maize seeding

The simulation results of popcorn maize seeding in the laboratory at a theoretical spacing of 20.993 cm with vacuum plates with 18, 22, 27, 31, 33, 36, and 44 holes at working speeds of 4, 6, 8, and 10 km/h are presented. At a working speed of 6 km/h, the vacuum plate n = 18 with a peripheral speed of 0.223 m/s achieved an average seeding spacing of 21.518 cm, with a reduction of 1 650/ha plants. At this peripheral speed, the plate achieved a QFI of 97.19 with Prec. index (CV m ) of 13.108. The vacuum plate n = 44 at the lowest acceptable speed of the seeding machine with a peripheral speed of 0.091 m/s achieved an average spacing of 20.816 cm with a QFI index of 98.63 while Prec. index (CV m ) was 8.397. By increasing the working speed of 10 km/h, the listed vacuum plate achieved an average spacing of 20.935 cm, and an increase in seeding was recorded for 187 plants/ha where the achieved value of QFI index was 97.31 while the value of Prec. index (CV m ) was 14.041. The choice of vacuum plate, as well as the speed of work had a statistically significant effect on the set of plants and the seeding spacing. The obtained results of vacuum plates n = 22, 27, 31, 33 and n = 36 are within the limit values of vacuum plates n = 18 and n = 44. ABSTRACT The results of simulation of popcorn seeding in the laboratory at a theoretical spacing of 20.993 cm with vacuum plates with 18, 22, 27, 31, 33, 36, and 44 holes ø 4.5 mm at working speeds of 4, 6, 8, and 10 km/h are presented. The research was performed on a test bench for a pneumatic seeding machine under controlled conditions of the working speed of the seeding machine under vacuum with a filled vacuum plate of 4.66 kPa. After research with different distances of seed brushoff teeth from the center of the hole, it was found that at position 12 on the scale (the top of the last seed brushoff tooth was 0.50 mm from the center of the hole) the best average seeding spacing of 24.671 was achieved that is -0.021 cm deviation from the theoretical distance used in the survey of the position of the seed brushoff. The research was performed only with a vacuum plate n = 22 at a working speed of 6 km/h and a high QFI coefficient of 98.13 and MULT 1.13 and a MISS index of 0.75% were achieved, with Prec. index (CV m ) of 9.930. Investigation of the negative pressure of 4.66 kPa at the vacuum plates holes established that the air velocity at a distance of 5 mm from the edges of the vacuum plate opening was 3.026 m/s, and at a distance of 10 mm a value of 1.514 m/s, was recorded. Based on this, the correctness of the selection of the maximum number of vacuum plates hole openings of n = 44 with an opening spacing of 15.52 mm was confirmed. It is theoretically possible, given the air velocity of 1.602 m/s in the central space between the two holes, that individual seeds can adhere to this space between two adjacent holes. At a simulated working speed of 4 km/h, the vacuum plate n = 18 with a peripheral speed of 0.223 m/s achieved an average seeding spacing of 21.518 cm (+0.525 cm compared to the theoretical spacing), with a decrease in the population of 1650 plants/ha. At this peripheral speed, the plate achieved a QFI of 97.19 and Prec. index (CV m ) of 13.108. The vacuum plate n = 44 at the lowest acceptable seeding speed (4 km/h), with a peripheral speed of 0.091 m/s achieved an average spacing of -0.177 cm from the theoretical spacing with a QFI index of 98.63, while Prec. index (CV m ) was 8.397. By increasing the working speed to 10 km/h, the vacuum plate n = 18 with a peripheral speed of 1.395 m/s achieved an average spacing of 0.895 cm compared to the theoretical spacing, and a decrease of 2.884 plants/ha was recorded. QFI index of only 83.06 while the value of Prec. index (CV m ) was 20.978. The vacuum plate n = 44 at the same speed of the seeding machine, with a peripheral speed of the plate of 0.571 m/s achieved an average reduction of the seeding spacing of -0.058 cm. Also there was recorded an increase in population for 187 plants/ha, with a QFI index value of 97.31, while the value of Prec. index (CV m ) was 14.041. The choice of vacuum plate, as well as the speed of work had a statistically significant effect on the composition of plants and the seeding interval. Since the vacuum plate n = 18 rotates twice as fast as the plate n = 36, a statistically significant difference was achieved only at higher working speeds, v3 and v4 (8 and 10 km/h). With the vacuum plates n = 31.36 and 44, regardless of the increase in speed from v1 to v4, there were no statistically significant differences in the average values of seeding spacing, so seeding can be done at higher speeds without disturbing the theoretical spacing.