GIBBERELLINS IN LEAVES OF ALSTROEMERIA-HYBRIDA - IDENTIFICATION AND QUANTIFICATION IN RELATION TO LEAF AGE

In alstroemeria (Alstroemeria hybrida), leaf senescence is retarded ef fectively by the application of gibberellins (GAs). To study the role of endogenous GAs in leaf senescence, the GA content was analyzed by c ombined gas chromatography and mass spectrometry. Five 13-hydroxy GAs (GA(19), GA(20), GA(1), GA(8), and GA(29)) and three non-13-hydroxy GA s (GA(9) and GA(4)) were identified in leaf extracts by comparing Kova ts retention indices (KRIs) and full scan mass sprectra with those of reference GAs. In addition, GA(15), GA(44), GA(24), and GA(34) were te ntatively identified by comparing selected ion monitoring results and KRIs with those of reference GAs. A number of GAs were detected in con jugated form as well. Concentrations of GAs in alstroemeria changed wi th the development of leaves. The proportion of biologically active GA (1) and GA(4) decreased with progressive senescence and the fraction o f conjugated GAs increased.