Abstract: The female, male and hermaphrodite flowers in different development stages of monoecious and andromonoecious nearisogenic lines of melon were used as materials to test the contents of 4 internal hormones and 4 polyamines with HPLC. The results showed that GA₃ content was higher in the young and old female and hermaphrodite flowers than in the male flowers; ZT and IAA content was higher in male flowers than in the female and hermaphrodite flowers for most of time in development period. ABA content rose obviously in middle and late development period of male flowers, and was higher than female flowers. The change trend of ABA content in hermaphrodite flowers was similar but ABA content markedly higher than female flowers; ZT/GA₃ in male flowers were higher than the female and hermaphrodite flowers. Thus it could be considered that higher GA₃ content, lower ZT and IAA content were beneficial to development of pistil, and higher ABA content was beneficial to development of stamen in middle and late development period. The order of Cad content was female, hermaphrodite and male flowers from high to low in the young period of flower bud. Cad content rose obviously in male and hermaphrodite flowers along with the development of flower bud, but it always was lower in female flowers. So higher Cad content was beneficial to development of pistil and lower content was beneficial to development of stamen in the early stage. On the contrary, higher Cad content promoted ripeness of stamen. Higher Spd content was beneficial to development of pistil in the early stage.

Key words: Melon, Flower bud, Internal hormones, Internal polyamines, HPLC