Safflower seeds development: physical changes and the role of gibberellic acid, light, and temperature

ABSTRACT Safflower is a crop with seeds containing high amounts of oleic and linoleic acids, which have applications in cosmetics, food, feed, and pharmaceutical industries. Safflower seeds are generally reported to undergo after-ripening and to have physiological dormancy. This study comprehensively analyzed the physical changes and the induction of dormancy and germinability in developing seeds to determine whether the safflower population is adequately developed during seed dispersal. From the 80th day after flowering (DAF), seeds were collected separately from plants on a weekly basis until 131 DAF, resulting in seven sampling dates. The changes in length, diameter, thickness, water content, and fresh and dry weight during seed development were measured. Simultaneously, the effects of dark and light, temperature, and gibberellic acid (GA3) (0, 50, and 100 µM) on seed germination, dormancy and germination characteristics of safflower seeds were investigated. The seeds ceased to increase in length, width and thickness, reaching a mature appearance at 131 DAF, with a dry mass per seed of 0.0443 g. The water content decreased between 117 and 124 DAF, indicating an obvious process of desiccation during the final stage of seed maturation. Germination capacity is acquired at 117 DAF, as evidenced by an increase in germination and a reduction in dormant seeds, particularly at low temperatures (10°C) and with GA3 supplementation. At 131 DAF, seeds exhibited 7.9 % water content, and there was an increase in seed germination and a decrease in seed dormancy status, regardless of GA3 supplementation and temperature.