Response of physical and mechnical properties of onion (Allium cepa L.) genotypes bulb to seed priming and size

In order to evaluate the effect of seed priming and seed size on physical and mechnical properties of onion genotypes a factorial field experiment based on a randomized complete block design with three replications was conducted in 2012 and 2013 cropping season at Agriculture and Natural Resources Research Center of East Azarbayjan, Iran. The experimental treatments included priming (at four levels: hydropriming, osmopriming (in %2 KNO3), priming with folammin amino acid (in 2%) and control (without priming), seed size (at three levels: small, medium, large) and cultivars (at two levels: RedAzarshahr and Zarguan). Following characteristics such as physical and mechnical properties include: arithmetic mean diameter, geometric mean diameter, sphericity, frontal surface area, cross-sectional of area onion, static coefficient of friction, angles of repose and terminal velocity were studied. Analysis of variance for the measurd traits indicated that all characteristics significantly were affected by treatment and seed size. Results showed that seed priming and seed size improved physical and mechnical properties characteristics. The highest arithmetic, geometric mean diameter, frontal surface area, terminal velocity, were obtained from plant that primed with folammin amino acid 56.39,53.64, 36.27 mm 4.87 m/s, respectively, and the lowest were achieved from control plants. The highest repose angle filling and emptyin were obtained from control 46.7°, 23.17° respectively, and the lowest were achieved from primed with folamin. Also the highest static friction coefficient were obtained from control on plywood (1.6) and lowest were achieved from primed with folamin (0.67) on galvanized iron surfaces.