Epsilon Open Archive

Abstract

The utilization of rose hips has a long tradition in Sweden, where they are used for the manufacturing of a popular dessert soup rich in vitamin C. In the mid 1980s a project was initiated at Balsgård, situated in the south of Sweden, with the aim to develop rose cultivars as a field crop for rose hip production. In the present thesis, some aspects of the domestication process in wild roses for fruit production are reported and discussed. Most of the papers concern species within section Caninae. All of these species are polyploid and characterized by their unique meiosis with unequal distribution of chromosomes from the parents to the offspring. The plant breeding program was divided into three steps. In the first step, plant material was acquired from different sources. The second step involved intraspecific and interspecific crosses in section Caninae and the third step concerned intersectional crosses between sections Caninae and Cinnamomeae. Seed germination was studied with different temperature treatments, and differences in amount of germination among the species were noted. Morphological diversity within and between three species, belonging to section Caninae, R. dumalis, R. rubiginosa and R. villosa was investigated. Rosa dumalis demonstrated the most pronounced intraspecific variation, whereas R. rubiginosa was very homogenous. Similar results were obtained when offspring plants were screened for fruit traits, such as fruit weight, % fruit flesh, % dry matter and vitamin C. Matroclinal inheritance was demonstrated with molecular markers (RAPD) in a pair of reciprocal crosses between R. dumalis and R. rubiginosa. The development of colour and some other fruit characteristics during ripening was studied for 6 weeks in R. dumalis, R. rubiginosa and R. spinosissima. For R. dumalis and R. rubiginosa it is possible to use colour as an indicator of optimum harvesting time. In R. spinosissima the fruits should be harvested in the middle of September, when most of the fruit traits have reached an optimum. Seedlings from 11 intersectional crosses (Caninae and Cinnamomeae) were screened for blackspot, leaf spot, powdery mildew and rust. Blackspot was the most severe disease followed by leaf spot, whereas symptoms of powdery mildew and rust were rare.