Regulation of dormancy break and germination of safflower seeds: the role of GA₃, light and cold temperatures

Abstract

The safflower crop is considered a great alternative for crop rotation since drought tolerance and low production cost are attractive for its choice. However, safflower seeds show dormancy soon after dispersal from the mother plant, making it difficult to successfully establish plants using newly harvested seeds. The influence of temperature, gibberellin and light/dark on dormancy break of safflower seeds during storage were investigated. In a completely randomized design, freshly harvested seeds or stored for 100 and 200 days (paper bag, 20 °C/ 60% UR) were treated with GA₃ (0 and 100 µM), at 4, 10 and 25 °C, in the presence and absence of light, during the germination test. Seeds were evaluated for germination percentage, germination speed and seedling survival after 21 days. The temperature of 10 °C, in combination with GA₃ (0/100 µM), or light/dark, provided the highest seed germination results, for freshly-harvested seeds and stored seeds. Collectively, these observations indicate that dormancy was not affected by gibberellic acid (100 µM GA₃) and the germination results at 21 days were significantly higher, in relation to the use of GA₃, under light or dark. Recently harvested seeds could efficiently germinate at 10 °C in the dark, while seeds dry-stored at 20 °C had decreased germination percentages.

Keywords:
storage; Carthamus tinctorius; gibberellic acid-3; root protrusion