Inheritance of Fruit Ripening Time in Oriental Pear (Pyrus pyrifolia var. culta Nakai)

To improve the breeding efficiency of oriental pear, heritability, correlation and frequency distribution of fruit ripenin g date were analyzed using 4,035 seedlings obtained from 15 families between 13 parental cultivars. Although variation of fruit ripening time was higher in most early-ripening parental cultivars than in late-ripening parental cultivars, according to anal ysis of average, standard deviation, and coefficient of ripening variation for ten years, fruit ripening time obtained from all pare ntal cultivars was inherited narrower and more stable variation than others fruit trait, with 0.92-3.41 in coefficient of variation. The heritability of fruit ripening time was calculated to be over 0.8 in almost all crosses and average fruit ripening time of seedlings from cross combinations could be predicted based on that of the parental cultivars due to its superior heritabilit y relative to other fruit traits. The average ripening time was earlier than the mid-parental value in families obtained from cro ss combinations using at least one late-ripening cultivar as parent, indicating that the early-ripening trait was more likely to b e dominant compared to the late-ripening trait. By contrast, average ripening time was clustered in families of crosses not only between mid-season and early-season cultivars, but also between mid-season and mid-season cultivars. There was highly si gnificant relationship (at 0.68) between mid-parental and progeny mean fruit ripening time. The correlation between fruit ripening time and fruit weight was also highly positive and thus, the mid-parental fruit ripening time could be a potent criterion for indire ct selection of fruit weight.Additional key words: