Gibberellins and Growth Inhibitors in Spring Bleeding Sap, Roots and Branches of Juglans regia L.

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Abstract
The main gibberellin found in the spring bleeding sap of the walnut tree was identified as GA19 and quantified by gas chromatography-selected ion monitoring (817 pg/ml). The second minor gibberellin (12 pg GA3-equiv./ml) was chromatographically similar to GA53. Both gibberellins occur in their free forms and as neutral ester-like conjugates. In the roots, these free gibberellins and an additional gibberellin glucoside-like component were found in late winter. In the bleeding sap, branches and roots, abscisic acid was identified by gas chromatography and mass spectrometry. In the sap, its amount was determined to be 34 ng/ml. ABA was not found in a conjugated form, but the branches contained a neutral ester-like conjugate of 4′-dihydrophaseic acid, an ABA metabolite, which after hydrolysis was identified by combined gas chromatography-mass spectrometry.