Studies in seed dormancy : VIII. The identification and determination of gibberellins A1 and A 9 in seeds of Corylus avellana L.

The three major fractions (II, III and V) of the five fractions of gibberellin (GA)-like activity obtained by the thin layer chromatographic purification of an extract of hazel embryos have been examined by gas liquid chromatography and combined gas chromatography-mass spectrometry. By these techniques GA1 was identified as the methyl ester trimethylsilyl ether in fraction II and GA9 as the methyl ester in fraction V. Both substances were clearly separated from other components by gas liquid chromatography so that accurate determination of their concentrations was possible. GA1 accounted for most of the activity found by bioassay in fraction II while GA9 accounted for only part of the activity of fraction V. The GA-like substances in the less biologically active thin layer chromatography fractions have not yet been identified.Freshly harvested seeds contained GA1 but GA9 was not detected. After 28 days dry storage and 42 days imbibition and chilling at 5°, the GA1 content was very low and GA9 was still below the limits of detection. On subsequent exposure of the seeds to a temperature of 20° for 8 days, there was a 40-fold increase of GA1 and at least a 300-fold increase of GA9.