Physical and Mechanical Properties of Giza Sabini Onion Bulbs for Improved Storage and Effective Environmental Control under the conditions of Sohag Governorate

This study aimed to evaluate key physical and mechanical properties of the Giza Sabini onion cultivar grown under Mesqawe and in-dry conditions. The primary objectives were to improve onion storage methods, promote water-saving practices during cultivation, and identify suitable physical and mechanical characteristics that meet international market and export standards. The physical properties assessed included axial dimensions, arithmetic and geometric mean diameters, mass, density, surface area, packing coefficient, and sphericity. Mechanical properties such as the static coefficient of friction and firmness were also measured. For Mesqawe onions, the average height (H), maximum diameter (Dmax), and minimum diameter (Dmin) were 65.00 mm, 76.02 mm, and 73.19 mm, respectively. In comparison, in-dry condition onions recorded values of 54.09 mm, 67.24 mm, and 63.81 mm, respectively. The arithmetic and geometric mean diameters were 71.40 mm and 71.16 mm for Mesqawe samples, and 61.71 mm and 61.38 mm for in-dry samples. The average mass and density were 175.36 g and 0.977 g/cm³ for Mesqawe onions, versus 127.36 g and 1.058 g/cm³ for those grown under in-dry conditions. Surface area, sphericity, and aspect ratio were also higher in Mesqawe onions, with values of 160.8 cm², 109.64%, and 117.02, compared to 120.7 cm², 113.69%, and 124.50 for in-dry samples. These findings provide valuable insights that support the development of improved post-harvest strategies, enhance water-use efficiency in onion cultivation, and help align product quality with international standards for export.