Effects of moisture content on geometrical and gravimetrical properties of cotton seed

Designing the equipment for processing, sorting, sizing and other post-harvest processes of agricultural products requires information about their physical properties. In this research, the effect of moisture content on the geometrical properties (length, width, thickness, geometrical and arithmetic mean of diameter, surface area, projected area and sphericity coefficient) and gravimetrical properties (thousands seed weight, volume, true and bulk density, and porosity) of seeds of two cotton varieties (Sahel and Saiokra) were investigated in a Completely Randomized Design (CRD) arranged in a 2 by 5 factorial experiment (two levels of varieties and five levels of moisture content) In engineering lab of Golestan Agricultural and Natural Resources Research and Education Center. With increasing moisture, the length of cotton seed of Saiokra and Sahel varieties were in the range of 8.82-9.15 mm and 8.77-8.91 mm, respectively, thickness in the range of 3.96-4.16 and 4.24-4.37 mm, respectively, geometrical mean of diameter in the range of 5.52-5.73 mm and 5.48-5.76 mm, respectively and sphericity coefficient in the range of 62.7 mm and 64.7-65.4 mm, respectively. The results showed that there was positive linear correlation between moisture content and cottonseed length, width, thickness and geometrical mean diameter. With increasing moisture content, seed volume were in the range of 1.00-1.22 cm3 and 0.86-1.14 cm3, respectively, bulk density in the range of 514-576 kg/m3 and 555-588 kg/m3, respectively, and porosity in the range of 38.5-62.6 and 42.9-51.9 percent, respectively. For showing variation of gravimetrical properties of seeds of two cotton varieties studied, with increasing moisture content, the first order regression equations with high coefficient of determination (R2) were fitted. Bulk density showed linear reduction with an increase in moisture content with high coefficient of determination.