Pollen tube behaviors in self-incompatible and self-compatible Citrus cultivars

To observe pollen tube behavior in the pistils of ten self-incompatible Cit rus cultivars, bud pollination, delayed pollination, self-pollination and c ross pollination were carried out. In self-pollination, of self-incompatibl e cultivars, pollen tubes were perfectly arrested in the stigmas and styles by 6 days after pollination, while in three self-compatible and 19 cross-c ompatible pollinations pollen tubes penetrated into the ovaries by 4 to 8 d ays after pollination. Various abnormal behavior and morphology of pollen t ubes were observed in both incompatible and compatible pollinations, but we re less common in the compatible ones. In the pistils of self-incompatible cultivars self-pollinated two days before anthesis and two days after anthe sis, the self-incompatible pollen tubes ceased to grow in the stigmas and s tyles, while in the pistils self-pollinated 4 and 6 days before anthesis ma ny pollen tubes reached the ovaries. However, numbers of pollen tubes penet rating the ovaries were different tit different cultivars. In tile pistils of self-incompatible cultivars self-pollinated 4 days after anthesis, polle n tube growth was enhanced to some extent, while in those self-pollinated 6 and 8 days after anthesis pollen tubes could not detected probably because of the degeneration of the styles. These studies suggested that in the pis til of self incompatible Citrus self-incompatibility initiates 6 days befor e anthesis and increases tip to the day of anthesis and that some of the cu ltivars have a common S allele that controls self-incompatibility.