Abstract
Endogenous cytokinins in Delaware grape berries were separated and partially purified for, their identification and the relationship between seeded berry growth and free cytokinins in the berries were studied.
1. Cytokinin activities in the cluster just before anthesis and in the pericarp during flowering were markedly high. This activity in the pericarp decreased gradually thereafter and almost disappeared 50 days after anthesis.
2. There was a close relationship between cytokinin activity in seed and growth of seed. High activity of cytokinin was observed during the rapid growth stage of seed.
3. At least two free cytokinins were present in the seeded grape berries. Zeatin and zeatin riboside were supposed to be responsible for the activities in the ammonia eluated fraction (AE).
4. In addition to these free cytokinins, at least two unknown cytokinin-like substances were present in the grape seed.
