Levels of Endogenous Indole-3-acetic Acid in Achenes of Rosa rugosa during Dormancy Release and Germination.
Indole-3-acetic acid (IAA) in highly purified extracts of rose achenes (Rosa rugosa var rubra) was quantified by means of ion-pair reversephase high performance liquid chromatography with spectrofluorimetric detection. Changes in IAA content were determined during a 14-week 4 degrees C stratification, which leads to dormancy breakage, and during subsequent germination at 17 degrees C. IAA was also determined in achenes stratified in parallel at 17 degrees C, which does not induce release from dormancy. IAA decreased during the first 2 weeks of stratification both at 4 degrees C and at 17 degrees C. IAA remained low during the remaining 12 weeks of stratification at 4 degrees C, whereas it continued to decrease in achenes kept at 17 degrees C. An immediate increase in IAA during germination was followed by transients in the IAA level. The results suggest that IAA is without a regulating role in dormancy release although it seems to be involved in the germination process.
Tillberg
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Department of Botany, University of Stockholm, S-106 91 Stockholm, Sweden.