Abstract:The endogenous hormone levels of cytokinin, gibberellin, auxin and abscisic acid in pistillate floral and vegetative buds,collected from early and late-fruiting types of 3-year-old walnut seedlings respectively,were measured using GLC-ECD or FTD at the stage of pistillate flower differentiation. Expressed sequentially as their relative amounts, the changes of these hormonal levels in both buds can be described simply and directly as follows, pistillate floral bud, (+,-,-,-); vegetative bud (-, +, +.+).This pattern suggests that (1) pistillate flower differentiation is the result of a specific balance of the four hormones acting in bud meristem tissues, and (2) the ratio of cytokinins to gibberellins appears to be positively correlated with the theoretical and practical ability of these tissues to form pistillate floral primordia, where the ratio of pistillate floral bud was "+/-" or 3.0,and vegetative bud was "-/+" or 1.2.In this paper, the practical significance of the endogenous hormone pattern, and the nature of juvenility for walnut were also discussed.