Articles
INITIATION OF SOURCE–SINK RELATIONS DURING HORSE CHESTNUT SEED GERMINATION
Article number
835_12
Pages
137 – 142
Language
English
Abstract
Initiation of source-sink relations was studied in terms of carbohydrate composition and content in the embryo axes of horse chestnut seeds during cold wet stratification.
Freshly-fallen seeds (deep dormancy) and seeds after 4 weeks (slow dormancy release), 9 weeks (dormancy release) and 16 weeks (loss of dormancy) of stratification were incubated in water at 27°С in darkness.
The samples of embryo axes were taken at the beginning of imbibition, in the middle of imbibition and at radicle protrusion.
Dry material was analyzed by gas chromatography.
The pattern of carbohydrate metabolism in embryo axes of imbibing seeds was similar during the entire period of dormancy release, its rate increased in the course of stratification because imbibition time up to radicle protrusion gradually shortened.
During the imbibition time, the embryo axis cells prepare for elongation and culminate this preparation in radicle emergence (growth initiation). Sucrose content is maintained at high level throughout the entire imbibition time.
Oligosaccharide breakdown occurs during the first half of imbibition, but then ceased.
During the second half of imbibition, an active accumulation of fructose and glucose was mainly due to degradation of sucrose imported from cotyledons.
Thus, an initiation of sourcesink relations occurs in imbibing seeds prior to the beginning of cell elongation in seed embryo axes, being its prerequisite as a process providing the accumulation of osmotica along with sucrose metabolization.
Freshly-fallen seeds (deep dormancy) and seeds after 4 weeks (slow dormancy release), 9 weeks (dormancy release) and 16 weeks (loss of dormancy) of stratification were incubated in water at 27°С in darkness.
The samples of embryo axes were taken at the beginning of imbibition, in the middle of imbibition and at radicle protrusion.
Dry material was analyzed by gas chromatography.
The pattern of carbohydrate metabolism in embryo axes of imbibing seeds was similar during the entire period of dormancy release, its rate increased in the course of stratification because imbibition time up to radicle protrusion gradually shortened.
During the imbibition time, the embryo axis cells prepare for elongation and culminate this preparation in radicle emergence (growth initiation). Sucrose content is maintained at high level throughout the entire imbibition time.
Oligosaccharide breakdown occurs during the first half of imbibition, but then ceased.
During the second half of imbibition, an active accumulation of fructose and glucose was mainly due to degradation of sucrose imported from cotyledons.
Thus, an initiation of sourcesink relations occurs in imbibing seeds prior to the beginning of cell elongation in seed embryo axes, being its prerequisite as a process providing the accumulation of osmotica along with sucrose metabolization.
Keywords
Aesculus hippocastanum, dormancy release, embryo axis, carbohydrates, sucrose import, osmotic pressure, growth initiation