Pollen diameter relates to seed production in cut roses

Rose breeding’s ultimate goal is to create new cultivars for the cut rose or garden rose market. Unlike extensive hybrid breeding programs undertaken in other species, few databases on rose breeding are available for research. Nevertheless, breeding efficiency in roses deserves attention, as hip contents usually range between one and 30 seeds, of which less than 50% germinate. A database from a cut rose breeding company was analysed and 11 cultivars varying in seed production were selected. Male fertility was studied in these cultivars through in vitro pollen germination and pollen size. Pollen diameter was a particularly valuable parameter for the evaluation of male fertility.