Determination of the apomictic fruit set ratio in some Turkish walnut (Juglans regia L.) genotypes

This study was carried out to determine the amount of apomictic fruit set in 10 Turkish walnut (Juglans regia L.) genotypes in 2001, 2002 and 2003. Yalova-1, Şebin, Bilecik, KR-1, KR-2, Şen-2, 07-KOR-1, Tokat-1, Kaman-1 and Kaman-5 cultivars and selections were used in the experiment. Female flowers were bagged and/or pollinated with pollen of the apple cv. 'Golden Delicious' (Malus x domestica Borkh.), and the apomictic fruit set was determined 8 weeks after anthesis. The percentage of apomictic fruit set without pollination ranged from 0.5% to 1.6% in 5 walnut genotypes, namely Yalova-1, Bilecik, 07-KOR-1, Tokat-1 and Kaman-1, in the first 2 years. In the third year, the highest apomictic fruit set (6.4%) was obtained from Tokat-1 after pollination with apple pollen. Apple pollen did not induce apomixis in the other 4 genotypes. The results indicated that apomictic fruit set is insufficient for economical seed and crop production in these ten Turkish walnut genotypes. © TÜBITAK.