Dormancy-breaking and germination requirements of Thalictrum squarrosum Stephan ex Willd. seeds with underdeveloped embryos

Abstract

The timing of seed germination has a significant effect on the life cycles and fitness of plants. Thalictrum squarrosum is a perennial herb with medical and ornamental value. However, the dormancy type and the regeneration strategy it uses to adapt to the natural habitat have yet to be investigated. The present study determined the seed germination requirements of T. squarrosum seeds and characterized the type of seed dormancy observed in this species. The results indicate that seeds of T. squarrosum had differentiated but underdeveloped embryos. After 30 days of incubation under 5/15, 10/20, 15/25, and 20/30 °C in light/dark conditions, no seed germination was observed, which indicated that the seeds had a morphophysiological type of dormancy. After 12 weeks of cold stratification, > 90 % seeds germinated at 5/15 and 10/20 °C. In addition, a gibberellic acid (GA3) treatment can substitute for the need for cold stratification and successfully broke dormancy in T. squarrosum seed. Seeds treated with 1000 mg/L GA3 had higher germination rates than those treated with 10 or 100 mg/L GA3. Embryo growth and germination began in February under natural conditions of the year following production. We conclude that T. squarrosum seed exhibits non-deep simple morphophysiological dormancy. These findings will enhance our understanding of the regeneration strategy of T. squarrosum that allows it to adapt to the environment and will offer a reference to horticulturalists and seed ecologists in understanding the germination processes of T. squarrosum.