Abstract
Some fundamental experiments were carried out to increase information about self-incompatibility on Hassaku (Citrus hassaku Hort. ex Tanaka). The following results were obtained.
1. Using isoelectric focusing analysis, buffer-soluble glycoproteins in self-pollinated pistils 15 minutes after pollination were compared with those in pistils that were cross-pollinated with Hyuganatsu (C. tamurana Hort. ex Tanaka). Some qualitative differences between self- and cross-pollinations were observed on every part of the pistils, but these were not so great as those 30 minutes after pollination reported in a previous paper.
2. Through an in vitro pollination in petri dishes, the growth of the self-pollinated pollen tubes was not stimulated even by the partial excision of styles or ovaries before pollination, and the tubes stayed long in the stigmas.
3. When immature flower buds, half the length of the mature ones, were self-pollinated after the stigma was smeared with an exudate of‘Banpeiyu’flowers at the stage of one day before opening, many self-fertilized seeds of Hassaku were obtained.
These results indicate how critical the stigmas are in the incompatibility of Hassaku, although it is a gametophytic incompatible plant.
