Influence of water stress on engineering characteristics and oil content of sunflower seeds.

Knowing some physical and mechanical characteristics and oil percentage of sunflower seeds could be useful for harvesting and processing equipment and activities such as transportation, storage, food production processes and establishing database of this seed. The main aim of this research was to study the effect of water stress during irrigation on seed's properties and quality. For this purpose, a field experiment was done under four deficit irrigation treatments [80%, 60%, 100-80 (100% irrigation requirement ETc to seed formation, and then reduced to 80% until harvesting) and 100-60% (100% ETc to seed formation, and then reduced to 60% until harvesting)] in comparable with full irrigation (100%). Geometrical, gravimetrical and mechanical characteristics as well as oil seed content and yield of sunflower seed were estimated. Result showed that there was no significant effect of low (100-80%) and medium (80%) irrigation deficit treatments on geometrical, gravimetrical and mechanical characteristics, while applying 60% of irrigation requirement (ETc) showed a significant effect on them. On the other hand, low and medium irrigation stress treatments improved the oil yield and seed oil content. The highest increase was 8.54% and 5.6% for oil yield and oil content respectively, considering T100-80 followed by applying 80% ETc, but with high water stress (60% ETc) oil yield and seed oil content significantly decreased.