Abstract
We analyzed fruit and seed sets after self-pollination in 3 apple cultivars. Between 1998 and 2001, we carried out self-pollination of cultivars ‘Megumi’, ‘Orin’ and ‘Fuji’, which exhibit different levels of self-incompatibility. In addition, we carried out self-pollination of ‘Fuji’ using X-ray irradiated pollen. Self-pollination of ‘Fuji’ showed percentages of fruit sets ranging from 0 to 4.5% over 4 years. In contrast, self-pollination of ‘Megumi’ and ‘Orin’ showed higher percentages ranging from 40 to 48% in the 2nd year and from 16.3 to 38% in the 3rd year. There were no differences in fruit set between experiments using X-ray irradiated pollen and non-irradiated pollen. ‘Megumi’ showed the production of seeded fruits, however, most of ‘Orin’ resulted in the production of fruits without seeds. We carried out self- and non-pollination of ‘Orin’, resulting in a high percentage of fruit set on average in all cases. All trees showed fruit but no seed. These results demonstrated that ‘Orin’ possess autonomic and/or stimulative parthenocarpy. From self-pollination of ‘Fuji’, we obtained many progenies from fruits containing seeds by the application of embryo culture, however, the percentages of seed set in ‘Fuji’ were less than those in ‘Megumi’. PCR amplification using S-allele-specific primers showed the possibility that some progeny were derived from self-compatible fertilization. These self-pollinated plants were grown in green house, however, some plants showed abnormal phenotypic appearances.
