Germination responses to temperature and water potential as affected by seed oil composition in sunflower

Sunflower genotypes with increased concentration of stearic and oleic acids have been developed to fulfil industrial specific requirements. Fatty acid composition of membranes has been widely described to affect seed germination, but the effect of composition of reserve lipids on germination is still unknown. Two experiments were conducted including: traditional (high linoleic), high stearic-high oleic, high stearic-high linoleic and high oleic genotypes. Thermal and hydrotime analyses were performed on germination data obtained from the incubation of seeds at different temperatures and water potentials. Fatty acid composition affected the parameters values of thermal time model. Base temperature was inversely related to linoleic acid concentration. Genotypes with high linoleic acid concentration germinated earlier at low temperatures, while no significant differences among genotypes at temperatures above 15 °C were found. High stearic-high oleic genotypes showed lower thermal time requirement for 50% germination than traditional and high stearic-high linoleic genotypes. The parameters of hydrotime model were not affected by fatty acid composition, but at low water potentials and high temperatures thermo-dormancy was induced and strongly reduced final seed germination in all genotypes studied. In conclusion, breeding for higher oleic acid and lower linoleic acid concentration in sunflower oil may affect seed germination performance at low temperatures.