The main objective of this study was to design a pneumatic disk with four-rows for planting rapeseed and to investigate its performance under several rotating speeds and vacuum pressure values. The effects of rotating speeds, vacuum pressure and rows on seed sucking and retaining were inspected. Six rotating speeds (5 r/min, 10 r/min, 15 r/min, 20 r/min, 25 r/min and 30 r/min) incorporated with the application of vacuum pressure were employed for detecting the optimum vacuum amount that was sufficient for seed sucking under each speed. These values of vacuum were found to be 1.1 kPa, 1.25 kPa, 1.35 kPa, 1.65 kPa, 1.8 kPa and 2.0 kPa, respectively.Moreover, a regression model was developed for predicting of vacuum pressure that corresponds with each rotating speed. Based on seed mass analysis, statistical differences were found at 5% significance under the influence of speeds and negative pressure and existed also between and within rows according to Duncan's Test.The highest seed mass means of 3.17 g and 3.96 g were obtained by row 1 under the effects of speed and vacuum pressure, respectively, while the lowest means of 2.79 g and 3.05 g were attained by row 4. Due to the influence of rows, important differences were occurred between row 1 (closer to the center of rotation) and row 4 (farther one), particularly under high speeds (25 r/min and 30 r/min).Results concluded that, pneumatic disk with multiple-rows could be satisfactorily used for seed sowing with a little variation in seed amount between rows without any seed damage. The rows of hole farther from plate center of rotation were obviously influenced by angular velocity and vacuum amount rather than the closer ones.

The aim of the study was to examine and compare the impact of laboratory and field trials on kernels distribution accuracy of a multi-rows pneumatic plate metering device. The effect of the two methods was verified at 15 and 20 r/min plate rotating speed integrated with most favorable values of 1.2 and 1.4 kPa vacuum pressures, respectively. A constant forward velocity of 2.7 km/hr was utilized for belt test and seed planter. Results exposed that vacuum amounts utilized with mentioned speeds were adequate for achieving precise seeding. Under both methods and speeds, laboratory attempts were found to be better in quality index than field trials with some propensity of 15 r/min to be superior. The lowest quality index obtained was 87.3% by field test, while worst miss and multiple indexes were 5.36% and 8.06%, respectively. Rows consistency CV was beneath 1.5% and the stability not surpassed 7.1%. Due to a set of factors confronting seed preciseness in the field, results concluded that more endeavors are robustly required to control such factors.

This study was conducted at College of Engineering, Huazhong Agricultural University, China, 2019. It aimed to inspect theinfluence of two devices on seed precision performance of a multi-rows pneumatic disk metering device. Curved-edge and positive air blower were the two devices specifically used at four plate velocities coupled with their well-matching vacuum levels. Seed distribution of the two methods was also verified at 15 and 20 r/min incorporated with 1.2 and 1.4 kPa vacuum pressure, and 0.9 and 1.0 kPa positive pressure, respectively. Results exposed that vacuum amount utilized with mentioned speeds were adequate for attaining closer rows pick-up with consistency CV not surpassed 2.84%. The lowest quality index attained was 89.88%, while miss index not exceeded 7.1%, and rows stability CV was below 1.15%. Curved-edge device was found to be superior to air blower in quality index, miss index and rows stability. Study results concluded the appropriateness of the devices methods for precise seeding with a little variance, and more precise devices set up may generate better results.

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