Effect of Moisture Content on Some Physical and Mechanical Properties of Wheat (Triticum aestivum L.) Seeds

The design, improvement, and use of seed planting, harvesting, and postharvest equipment depend on the physical and mechanical properties of the specific crop type and variety. However, this information is lacking for wheat varieties produced in different regions of Ethiopia. The objective of this study was to determine the effect of moisture content (8.5%, 13.5%, 18.5%, 23.5%, and 28.5%) on physical and mechanical properties of three wheat varieties (Danda’a, Jalanne, and Kakaba) commonly cultivated in Ethiopia. A factorial combination of 3 (verities) × 5 (moistures levels) treatment levels was adopted with three replications. The variables studied were the grain size, shape, weight, bulk density, angle of repose, and coefficient of friction. The data were subjected to analysis of variance (ANOVA), and the Dunnett multiple range test was used to separate the means. Significance was accepted at p < 0.05. As moisture increased, the grain’s dimensions, shape, thousand kernel weight, coefficient of friction, and angle of repose increased while bulk density decreased. The bulk density decreased from 0.73 to 0.54 g cm^-3 as moisture increased from 8.5% to 28.5%. The study revealed substantial variation across moisture treatments, underscoring the sensitivity of grain physical properties to hydration levels. The mean values for grain length, surface area, and volume increased from 5.786 ± 0.253 to 6.525 ± 0.361 mm, 38.514 ± 2.997 to 49.627 ± 3.201 mm², and 22.531 ± 2.644 to 32.933 ± 3.201 mm³, respectively. Similarly, the thousand kernel weight, repose angle, and friction coefficient increased from 26.70 to 42.00 g, 23.20° to 34.70°, and 0.4142 to 0.8391, respectively. Variations in grain properties indicate the necessity for diverse design and calibration criteria for seed planting, harvesting, and postharvest equipment tailored to different wheat varieties at different moisture levels.