Genotypic Variation in Prolonged Dormancy Symptoms in Apple Progenies

Abstract

The variability of characteristics associated with prolonged dormancy in apple (Malus ×domestica Borkh.) progenies planted in the Western Cape region of South Africa was recorded over a three-year period. The time of initial vegetative and reproductive budbreak, the number of vegetative and reproductive budbreak, and the flowering duration were used as criteria. Data were collected on bearing trees of apple seedling families where the cultivars Anna and Golden Delicious were used as a common parent. Analysis of variance detected significant variation among seedling families for time of budbreak, number of breaking buds, and flowering duration in `Golden Delicious' families. `Braeburn' × `Golden Delicious' consistently produced seedlings with higher numbers of breaking buds and `Golden Delicious' × `Prima' showed significantly lower numbers than other `Golden Delicious' families. In `Anna' families, significant differences were found for time of budbreak. `Anna' families showed higher variability within families than `Golden Delicious' families. Comparisons of progenies of `Anna' and `Golden Delicious' showed large differences in variation for the time of budbreak and for duration of flowering. Mean budbreak of `Anna' progenies did not differ from `Golden Delicious' progenies. Associations were found between initial time of budbreak and number of breaking buds as well as time and flowering duration. Results reveal high genetic variance in prolonged dormancy symptoms among seedlings within apple families which can be directly ascribed to high levels of heterozygosity in the cultivars used, and should be further explored for the purposes of breeding and selection.