Effects of root pruning and uniconazole treatments on flower bud induction in peach [Pruns persica] seedlings of the current year

Root pruning, uniconazole treatments, and early sowing were performed in peach seedlings of the current year in order to hasten flower bud induction. Early sowing after stratification increased the growing period and node number, and resulted in inducing more flower buds. In 'Yaguchi', root pruning in early to middle July increased the number of plants with flower buds and the numbers of the flower buds, although its effects varied by year. In 'Hokimomo', root pruning in early July slightly increased the numbers of plants with flower buds. In 'Yaguchi', treatments with uniconazole significantly increased plants with flower buds and numbers of flower buds. Moreover, uniconazole significantly lowered the lowest node with flower buds, mean node number with flower buds and maximum node number. Although root pruning induced flower buds only on nodes formed after the treatment, uniconazole induced flower buds on nodes that had been formed before treatment. Root pruning induced flower buds that ranged from the node at treatment to the upper 60th node, while uniconazole formed flower buds from the lower 16th node to the upper 23rd node. Combined treatment with root pruning and uniconazole tended to increase the number of flower buds, which were distributed in intermediate parts of the two single treatments. These findings suggest that it is possible to promote phase transition of nodes from the juvenile phase to the transition or reproductive phase by early sowing and to suppress vegetative growth and accelerate flower bud differentiation by root pruning and uniconazole treatments in nodes at the transition phase on seedlings of the current year. Since uniconazole treatments induced flower buds at about the 70th node, 'Yaguchi ' seedlings of the current year could attain the transition phase around the 70th node at 6-7 months after sowing.