Transmission of Flower Traits and Fertility in Black Rose x Hybrid Tea Rose Cross Combination

Breeding studies of scented cut roses have gained significance recently. The Black rose, a naturalized old garden rose in Türkiye, is a valuable genetic resource for breeding programs due to its pleasant scent. This study investigated the fertility of the Black rose (Rosa odorata cv. Louis XIV, Halfeti rose) as a seed parent and its ability to transmit flower traits to offspring. Four commercial cut rose varieties with known pollen germination rates were used as pollen parents. Each combination underwent at least 33 pollinations, and the fruit set rate, the average seed number per fruit, and the seed germination rate were examined. Both parents and one-year-old F1 progeny were evaluated for petal number, scent, and flower color traits during two flowering periods. Cross-pollination resulted in fruit set rates ranging from 70.21% to 100.0%, average seed numbers per fruit ranging from 5.0 to 10.0, and seed germination rates ranging from 4.42% to 21.69%. Morphological characterization revealed that 5.05% of the progeny exhibited moderate to intense scent, 42.42% had sour cherry-colored petals, and petal numbers ranged from 9 to 54. Considering the overall efficiency of rose breeding programs, the findings demonstrate the promising fertility of the Black rose and its relative success in forming efficient combinations with hybrid tea roses. However, it also suggests that the Black rose is not as successful in transmitting the scent to its offspring as in transmitting the flower color.