Dormancy cycles in Aquilegia oxysepala Trautv. et Mey. (Ranunculaceae), a species with non-deep simple morphophysiological dormancy

Abstract

Seed dormancy and the formation of a soil seed bank is important plant regeneration strategies, especially if the environment is unpredictable. The present research explores how environmental factors control seed dormancy release, and how seed dormancy is related to the soil seed bank and regeneration of the perennial Aquilegia oxysepala. The effects of incubation temperature, light, cold and warm stratification, gibberellic acid (GA3) along with the germination phenology of A. oxysepala in the field were used to determine the type of seed dormancy. Seasonal change of seed dormancy was determined by regularly exhuming buried seeds and incubating them in laboratory conditions. A. oxysepala seeds has underdeveloped (small) embryos along with physiological dormancy at dispersal. With the increased amounts of cold stratification, the germination of A. oxysepala increased gradually. GA3 served as a substitute for cold stratification. Breaking of physiological dormancy under natural temperatures in the field occurred in winter, while growth of embryos and germination of seeds occurred in early spring. Viable seeds that had not germinated in early spring were induced into secondary dormancy by high soil temperatures. A. oxysepala provides one of a few examples of dormancy cycling in seeds with morphophysiological dormancy. Freshly matured seeds of A. oxysepala seeds have non-deep simple morphophysiological dormancy. The annual dormancy–non-dormancy cycle maintains the coordination between timing of seedling emergence with favorable seasons, thus increasing the survival chances of seedlings in environments with seasonal changes.