Abstract
Influence of flower location (distal, mid- or basal) on a shoot thinned to 3 flowers and whether or not the flowers were pollinated on the set of parthenocarpic fruit of kaki (Diospyros kaki L. f.) cvs. Fuyu and Hiratanenashi was investigated. The purpose was to clarify the relation between the set of parthenocarpic fruits and the relative sink strength of parthenocarpic and seeded fruits located at different positions on the same shoot.
1. Fruit set of pollinated and non-pollinated flowers was highest at the distal position and lowest at the basal one on a shoot.
2. The set of parthenocarpic fruits on the distal position on the shoot with non-pollinated 3 flowers was higher than that of seeded fruits at any position on the shoot with pollinated 3 flowers.
3. Seeded fruits set at a greater frequency than did the parthenocarpic fruits on the same shoot.
4. The parthenocarpic fruit set of non-pollinated 3 flowers on a shoot, especially at the upper position, decreased with decreasing length of shoot.
5. There was a significant difference in seedless fruit growth among the fruiting positions ; many smaller fruits tended to abscise.
6. Whether or not a parthenocarpic fruit set depended on its position and the presence of a seeded fruit on the same shoot. The variations in setting patterns of parthenocarpic fruits were very similar in 'Fuyu' and 'Hiratanenashi'.
We concluded that 1) a dominant factor of the variation of parthenocarpy in 'Fuyu' was more environmental than hereditary, 2) there was no significant difference in hereditary characteristics of parthenocarpy between 'Fuyu' and 'Hiratanenashi', 3) fruit drop of seedless fruit was induced by competition among fruits, and 4) the set of parthenocarpic fruits was achieved when the relative sink strength of seedless fruit was stronger than that of competing fruits.
