Breeding of new cultivars of the fruit crop Japanese quince (Chaenomeles japonica) in Latvia

Chaenomeles sp. is well-known as an ornamental plant. The breeding of Chaenomeles japonica as a fruit crop for processing started in Latvia. C. japonica is a very diverse in plant and fruit characters, and many important traits are controlled by additive as well as non-additive genes, so breeding of new cultivars took many years. Breeding strategy was based on extensive test crosses and progeny tests in field trials. Promising genotypes were obtained by performing hybridization, selection and evaluation in several populations. In 2012 the first cultivar ‘Rasa’ was registered in Latvia. Two other cultivars – ‘Darius’ and ‘Rondo’ – were created in the collaborative program with Lithuanian and Swedish breeders and registered in 2018. These cultivars are thornless, productive – total yield during 5 years can range from 20 to 28 kg bush^‑1, some years to 10 kg bush^‑1; resistant to leaf spot and fruit rotting. Fruits are yellow, 40-50 g, very acid (4.8-5% organic acids, mainly malic acid, also quinic and succinic acid), they contain 57-90 mg% vitamin C and 422-550 mg% phenolic compounds on average, ripen at the beginning or middle of September. As 80-90% of all studied genotypes were self-incompatible, partial self-fertility of ‘Rasa’ is a positive trait. Since Chaenomeles is relatively resistant to diseases and pests, it can be grown in an environmentally friendly way, and interest in it as a commercial fruit crop increases.