The Effect of Red Light, ABA, and K+on the Growth of Datura ferox Embryos and Their Relations with Photocontrol of Germination

Abstract

The growth rate of embryos isolated from dormant Datura ferox seeds was reduced 75% by 0.5 M mannitol. With mannitol + 20 mM KCl, the growth rate increased, but no significant difference was observed between embryos irradiated with red (R) and far-red (FR) light. When 0.5 M mannitol + 1 μM abscisic acid were included in the incubation medium, the response to K+ was negligible, but the growth rate increased significantly with R irradiation. Measurements of the K+ content of endosperm and embryo of intact seeds at different times before and after R irradiation showed no differences from the dark-incubated controls until 24 h after the radicle emerged. There was no change in the relative K+ content of the cotyledonary and radicle ends of the embryos. These data do not support the possibility of a light-dependent K+ transport as a key factor in the photocontrol of germination in D. ferox seeds.