Sour cherry breeding at Dresden-Pillnitz
The sour cherry breeding program was started in 1965 by Wolfram. The main breeding goals include: 1) high productivity, 2) fruit quality, 3) self-fertility, 4) disease tolerance to Monilinia ssp., Blumeriella jaapii and Prunus Necrotic Dwarf Virus, and 5) suitability for mechanical harvesting. Several crossing series have been carried out. To date, five new sour cherry varieties have been selected and released, and four new candidate varieties ('Rubellit', 'Achat', 'Jade' and 'Spinell') have been proposed for release. All varieties are self-fertile and characterized by good fruit quality. In most cases, they do not achieve the high yield of the 'Schattenmorelle', but they are more resistant to disease. Meiotic investigations were carried out to investigate the reason for the low fertility of sour cherry varieties. The result was an apparent relationship between low fruit set and the pairing frequencies of the chromosomes in metaphase I. The observed meiotic instability suggests that there is a disharmony in the genome constitution of the allopolyploid sour cherries.