Variation of gibberllins, cytokinins and abscisic acid in vegetative and flower buds in various periods of apple tree

In a study on the variation of gibberellins, cytokinins and abscisic acid in the leaves of vegetative and flower buds, 3 fractions of cytokinins were separated by sephadex-LH 20 column. Fraction A consisted of 0-100 ml eluate. While fraction B 100-200 ml eluate, and fraction C 200-300 ml eluate. The three fractions of cytokinins in flower buds were remarkably higher than that in vegetative buds, especially the fraction C was much more than the fraction A and B, the contents of gibberellins were slightly higher in the flower buds than in the vegetative buds during the flower bud differentiation, but the ratio of cytokinins to gibberellins were higher than in the vegetative buds. The former was 4.02 and the latter, was 1.69. A direct relationship was found between the ratio of endogenous cytokinins to gibberellins and the ability of the spur to produce flower buds. The role of the ratio of the two hormones in flower formation is discussed.