Characterization of apple accessions for traits of relevance for organic agriculture

Summary

The main goal of this research was to characterise the available apple accessions in the Netherlands, which will give a base for future breeding programs in the organic sector. Organic farmers, nowadays, depend on cultivars which are well suited for conventional conditions. Tree architecture has a major role for organic apples growth and should be taken into consideration in apple breeding programs. The common assumption among the organic sector is that many valuable traits, such as architectural traits, can be found in many old cultivars (cultivated before 1940) and should be integrated into future breeding programs. In order to provide the apple breeders with an accurate description material, an apple tree ideotype was first developed. Secondly, a methodology to assess the different traits was developed. The accessions were then evaluated according to the ideotype characteristics, and using the methodology developed previously. Eventually, the heritability of the most important traits was reviewed to complete the study and make it fully usable for further breeding purpose. According to tree ideotype study, which highlights the importance of tree architectural traits results, it is clear that conventional cultivars do not fit into the organic growers needs. However, the evaluation of the population using an improved methodology included a detailed scoring of fruit quality, tree architecture, diseases susceptibility and yield production, showed promising potential for future breeding perspective.