Relationships among apple fruit abscission, source strength, and cultivar

► We elucidated cultivar differences in the degree of self-regulatory abscission. ► The growth rate of a fruit cluster was constant for each cultivar. ► The constant growth rates of fruit cluster indicate the source strength. ► The degree of abscised fruitlets were correlated with the source strength. ► The source strength can be a useful index for selecting cultivars with self-thinning.