Fabrication and Evaluation of Grooved Seed Plate for Dry-bed Seeding of Rice Using Pneumatic Row Crop Planter

High water consumption and the cost of labor in rice transplanting method is the reason for growing tendency of farmers to Dry-bed seeding of rice in Iran. High consumption of seed and inadequate specialized machines are the problems in rice dry-bed seeding. At present rice dry-bed seeding is done with traditional drill seeder with more than of 90 kg/ha seed consumption. While planting one seed in hole with a 20×20cm planting pattern in dry-bed seeding can reduce seed consumption to 5 kg/ha. This research was conducted for fabrication and laboratory evaluation a special seed plate for rice dry-bed direct seeding with pneumatic planter. Design parameters of Seed plate were included six plate shapes and three seed hole diameters. Seed plate shapes included traditional plate without groove and five groove shapes on plate, including three trapezoidal grooves with wall angle of 30, 45 and 60 degrees and two semicircle grooves with the aperture opening 2 and 3mm and three seed hole diameters 1.2, 1.3 and 1.5mm at the three levels of vacuum pressure 40, 50 and 60 milibar compared in a completely randomized design in a factorial experiment with three replications. Indices were, seed number per hole, miss index, over index and precision of feeding index. The results showed that creating the groove on the seed plate resulted higher seed cell covering and reduced miss and over index. New grooved plates had higher precision of feeding and lower miss index than conventional seed plate. By increasing the vacuum pressure and the diameter of the seed hole, miss index decreased and over index and seed number per hole increased. By increasing the angle of the walls of the trapezoid grooves and aperture of the semicircle grooves miss index reduced and over index and seed number per hole increased. In general, the results of laboratory evaluation Showed that for direct seeding of rice in dry-bed condition with pneumatic planter, using the seed plate with trapezoidal groove wall angle of 45 degrees and a diameter of hole 1.2 mm and vacuum pressure 50 mbar were better than others.