Comparing plant morphology, fertility and secondary metabolites in Rosa hybrida cv Iceberg and its chromosome-doubled progenies

ABSTRACT: In commercial breeding of ornamentals variation in plant morphology, alteration of secondary metabolites involved in production of flower color and aroma or increasing fertility are very important. In the present investigation morphological characteristics, pollen viability, pollen germination, seed setting and secondary metabolites content of R. hybrida cv Iceberg (Triploid) were compared with its chromosome-doubled progenies. Pollen viability was assayed by fluorescein diacetat. Pollen germination was determined using different concentrations of boric acid. Seed setting was compared in the two genotypes when they were allowed to open pollinate. Phenolic, anthocyanin, flavonoid, and carotenoid contents were compared after deriving the extract from petals, using a spectrophotometer. The aromatic compounds were extracted using hexane and the absolutes were analyzed by gas chromatography–mass spectrometry. Results indicated that some of morphological characteristics were significantly higher in the triploids than the hexaploids. However, diameter of the flowering stem, breadth/length ratio of the leaves and vase life of the flowers were significantly higher in the hexaploids than the triploids. The highest percentage of pollen germination was observed at 10 mg l-1 boric acid in both cultivars. The pollen viability and percentage of pollen germination were significantly higher in the hexaploids (30.54%, 34.41%) than the triploids (9.96%, 14.53%). Although, the total content of phenolic compounds were significantly higher in the hexaploids than the triploids, but there was not a significant difference in anthocyanin, flavonoid and carotenoid content between the two genotypes. In total, 16 chemical constituents were identified in the essential oil of triploid and hexaploid genotypes, from which some of the chemical constituents were significantly higher in the hexaploid than the triploid roses.