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The effect of stratification on the endogenous levels of gibberellins and cytokinins in seeds of douglas‐fir ( Pseudotsuga menziesii (Mirb.) Franco) and sugar pine ( Pinus lambertiana Dougl.)
Author(s) -
TAYLOR J. S.,
WAREING P. F.
Publication year - 1979
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1979.tb00789.x
Subject(s) - gibberellin , cytokinin , zeatin , stratification (seeds) , germination , botany , douglas fir , sugar , horticulture , chemistry , biology , dormancy , auxin , seed dormancy , biochemistry , gene
Seeds of Douglas‐fir and sugar pine which had been exposed to various periods of moist chilling (stratification) were extracted and bioassayed for gibberellin and cytokinin activity. In Douglas‐fir a peak of gibberellin activity increased progressively during stratification and was seven times higher after 7 weeks, but declined subsequently. No change in the level of cytokinin activity was observed during stratification. However, a slight increase (1.7‐fold) occurred in stratified seeds placed at 22°C for 3 days. In sugar pine a high level of gibberellin activity, approximately 20‐fold higher than in unstratified controls, was present in extracts of seeds which had been stratified for 8 weeks. After 10 weeks of stratification cytokinin levels had increased approximately 200‐fold. Four cytokinin‐like substances were detected in seeds. Three of the substances are similar in their chromatographic properties to zeatin glucoside, zeatin riboside and zeatin, respectively. Both gibberellin and cytokinin activity declined rapidly after reaching maximum levels. In seeds with the coats removed, germination was rapid and complete in the absence of stratification. Prior to radicle emergence in coatless seeds cytokinin activity increased to a maximum (approximately a 1‐7‐fold increase) within 24 h. Significant levels of gibberellin‐like substances were present after 8 h. Gibberellin activity could not be detected in coatless seeds which were imbibed in AMO‐1618, and germination was inhibited significantly.