Determination of Apomictic Fruit Set Ratio in Several Romanian Walnut (Juglans regia L.) Cultivars

Apomixis, a natural process that allows clonal propagation by seed, is an important feature of walnut (Juglans regia L.). This study was carried out to determine the ability of apomictic fruit setting in twelve Romanian walnut cultivars. ‘Sibisel 44’, ‘Geoagiu 65’, ‘Germisara’, ‘Muscelean’, ‘Sarmis’, ‘Valcor’, ‘Valmit’, ‘Valrex’, ‘Jupanesti’, ‘Velnita’, ‘Orastie’ and ‘Argesean’ cultivars were used in the experiment. Female flowers were isolated with pergament paper bags and the apomictic fruit set was determined 8 weeks after anthesis. The apomixis degree was determined as the number of fruit calculated in relation to the number of isolated flowers. The percentage of apomictic fruit set without pollination in cultivars analyzed is low, ranging from 7.86% (‘Orastie’ cultivar) up to 12.46% (‘Jupanesti’ cultivar). The results indicated that apomictic fruit set is insufficient for economical seed and crop production in these Romanian walnut cultivars.