197 Bloom Phenology and Fertility of Sour Cherry Cultivars of Hungarian Origin at Two Different Growing Sites J. Nyéki a , N. Papp, L. Lakatos, M. Soltész and Z. Szabó University of Debrecen Institute for Extension and Development Debrecen Hungary A. Hegedus and J. Halász Corvinus University of Budapest Department of Genetics and Plant Breeding Budapest Hungary P. Hilsendegen and M. Balmer Dienstleistungszentrum Landlicher Raum Rheinpfalz, Kompetenzzentrum Gartenbau Neustadt an der Weinstraße Germany T. Szabó Research and Extension Centre for Fruit Growing Újfehértó Hungary Keywords: blooming, fertility, Prunus cerasus, sour cherry Abstract Analyses of flowering phenology were carried out at Újfehértó, Hungary and Oppenheim, Germany. In our long-term project, 88 sour cherry cultivars from Újfehértó and 105 cultivars from Oppenheim were evaluated over 27 and 12 years, respectively. All sour cherry cultivars from Újfehértó are characterized by the same late flowering period, which generally started on the 111 th day (Julian days) of the year and finished on the 121 st day. Besides genotype, several external factors have been shown to significantly influence the start of flowering period, which was closely correlated with the differences between day and night temperatures over the 30 days before flowering. In Oppenheim, ‘Gerema’ and ‘Schattenmorelle’ were characterized by extremely late bloom dates. Sour cherry cultivars selected in the region of North- Eastern Hungary are characterized by high fruit set after open pollination, exceeding 20%. The highest fruit set ratio (26.9%) was obtained with ‘Petri’. In Oppenheim, ‘Schattenmorelle’ was characterized by 15-20% autogamous fruit set, while open pollination set approx. 30-40% of fruits. In Újfehértó, over 27 years, flowers were destroyed by serious frost injury in two years. Based on several characteristics, the two late blooming cultivars that have been recently released, ‘Petri’ and ‘Éva’, appear be promising choices for commercial orchards in Hungary. INTRODUCTION Újfehértó is located in North Eastern Hungary, in a region traditionally known for sour cherry (Prunus cerasus L.) growing and many local cultivars (Nyéki et al., 2003, 2008). In the last century, many wild type trees were identified in the village and in abandoned orchards in home gardens (Szabó, 2007). Village people have selected genotypes that produce bigger and tastier fruits and have reliable productivity. One of the local Hungarian selections was transported to Michigan, USA and became a popular cultivar under the name ‘Balaton’ (Papp et al., 2010). The original Hungarian name of this cultivar was ‘Újfehértói fürtös’. Újfehértó is the village where this genotype was selected, while “fürtös” indicates its fruits are produced in dense clusters, in so-called bunches. This fruit is consumed fresh and is appreciated in the fresh market; however, they are also processed in many forms. One of these products is a special Hungarian kind of spirit with approx. 40% alcoholic content. The spirit “pálinka” made from ‘Újfehértói fürtös’ is under the protection of geographical indications. In West Germany, Oppenheim is an important region for cherry production and has a collection of 105 cultivars that were monitored in our study. Among these cultivars, a Email: erdodine@agr.unideb.hu. Proc. VI th Intl. Cherry Symposium Eds.: M. Ayala et al. Acta Hort. 1020, ISHS 2014