Morphology and Volatile Compounds Investigation in ‘Fragrant Frayla’ Collection of Garden Roses

Abstract

Summary The aim of this study was to investigate the morphological traits and fragrance-related volatile compounds in three garden rose cultivars from the 'Fragrant Frayla' collection: 'Draga Frayla', 'Jelena Frayla', and 'Lenka Frayla', bred by the private breeding company Pheno Geno Roses. The roses were cultivated under open-field conditions in Temerin, Serbia, without irrigation and chemical treatments. Vegetative and generative properties were assessed in June and September 2023, while headspace volatile extraction and gas chromatography–mass spectrometry (GC-MS) were employed to identify scent-related volatiles. All three cultivars exhibited high ornamental value, with shrub heights ranging from 47 to 67 cm, semi-upright to upright growth habits, double flowers with diameters from 6.6 to 8.2 cm, and petal counts from 35.8 to 83.8. Upon sensory evaluations, 'Draga Frayla', 'Jelena Frayla', and 'Lenka Frayla' were characterized by moderately strong, strong and moderate fragrances, respectively. Volatile analysis detected the presence of phenylethyl alcohol (up to 57.31% in 'Draga Frayla'), terpenoids (a total of 28.2% for citronellol, geraniol, and nerol, found exclusively in 'Jelena Frayla'), and hydrocarbons. Hydrocarbons containing fewer than 30 C-atoms were predominantly found in 'Draga Frayla' (accounting for approximately 25% of the total peak area), while those with more than 30 C-atoms were present at less than 20% in the strongly scented roses. The highest number of volatiles was detected in 'Jelena Frayla', the rose cultivar identified as the most fragrant. The results revealed a correlation between strong fragrance intensity and elevated levels of phenylethyl alcohol and alcoholic monoterpenes, whereas a diverse array of hydrocarbons, rather than their concentration, appeared to enhance scent emission.