Exploring genetic variability and floral trait inheritance in F₁ hybrids from climber × miniature rose crosses

Potted miniature roses are widely cultivated as popular indoor ornamental plants. Owing to increasing consumer demand, new varieties are introduced to the market each year. Cross-breeding remains the most prevalent method for developing potted miniature roses. In the present study, Rosa noisettiana Thory, a climber rose species, was used as the seed parent, while ten commercially popular miniature rose cultivars (Rosa White Star, Hot Jewel, Rosa Sweet Star, Rosa Bling Love Star, Orange Jewel, Rosa Shining Star, Rosa Lady Star, Orange Romance, Red Romance, and Sparkling Jewel) served as pollen donors. The success of hybridization was evaluated, and both quantitative and qualitative traits were analyzed in 861 F₁ hybrid individuals to assess the breeding potential of miniature roses. The percentage of pollen viability ranged from 17.71% to 46.79%, while the pollen germination rate varied between 10.33% and 21.68%. In total, 250 controlled pollinations were performed, all of which successfully developed into 250 fruits (hips). These fruits collectively contained 7,249 seeds. The results revealed that R. noisettiana × miniature rose combinations exhibited a 99.5% fruit set rate, with an average of 29.23 seeds per fruit and a seed germination rate of 20.53%. However, the recurrent blooming rate ranged between 15% and 34%, and many tall individuals were obtained from these crosses. Key commercial traits, such as flowering time, plant height, flower diameter, and petal number, were found to vary depending on the parental genotypes. In contrast, flower color did not exhibit as much variation as expected in the hybrid combinations. Based on these findings, further crosses should be conducted with different rose species to enhance genetic diversity in breeding programs and achieve more effective outcomes in the ornamental plant sector. Moreover, early selection methods utilizing genetic markers could be developed to increase the recurrent blooming rate and to obtain more compact plants.