Some Physical and Morphological Properties of Wild Sunflower Seeds

As part of a study to characterise and examine the use of wild sunflower species (Helianthus petiolaris Nutt), some physical properties and morphological characteristics of seeds from different locations in Argentina were determined. The oil content ranged between 27% and 30% (wb) and the moisture content varied from 8·9% to 10·4%. The average length, width, and thickness of the seed, measured with a micrometer, were 4·5, 2·02, and 1·2 mm, respectively. The calculated mean values of seed equivalent diameter, surface area, and sphericity were 2·25 mm, 16·2 mm2, and 0·48, respectively. The bulk and true densities measured with a hectolitre tester and by picnometry, respectively, were 350 and 399 kg/m3. The angle of repose ranged between 28·6° and 30·2°. The morphological characteristics as well as the hull thickness and percentage were also evaluated by scanning electron microscopy. The hull thickness and percentage had mean values 0·07 mm and 21%, respectively. Achenes presented straight and double hairs and a morphological study showed a pericarp structure with an amorphous and lignified fibre layer and air cavities between the inner parenchyma and the cotyledon.