Ornamental and Landscape Characteristics of Roses, Their Complexity, Contribution to the Overall Value of Cultivars, and Potential Applications of Use in Rose Breeding

Known as the “Queen of Flowers,” the rose is one of the most beloved flowers in the world. Although there are more than 37 000 cultivars of roses, novel forms must be created due to environmental and socioeconomic changes or advancements. An extensive knowledge of varietal variability is crucial for rose breeding, but the abundance of rose types and various estimating techniques sometimes hinder objective assessment. Different rose cultivars with varying features and fitness for use were evaluated in the current study, belonging to four groups: shrubs, floribundas, hybrid teas, and climbers. Based on the main traits of plant growth and vigor, flowers, foliage, and reaction to biotic and abiotic stress factors, it was computed the overall value, as a “general value” of tested cultivars and how the component elements (morphological traits or appreciate visually through notation) contribute to the ensemble of the ornamental and landscaping value. Valuable cultivars have been identified that deserve to be used in similar ecological conditions, or that can be recommended as potential parentals in new hybridizations (e.g. ‘Monica’ for the overall quality of the flowers and ornamental elements, ‘Pasiune in Mov’ and ‘Rosagold’ for fragrant flowers, ‘Perla Transilvaniei’ for intense flowering, and ‘Rosarium Utersen’ for durability of the flowers). In addition to the phenotypic evaluation, the genetic evaluation revealed information about the potential for hybridization using the cultivars as parents and the possibility of transferring the desired features to their offspring. Hypotheses were also issued regarding the use of appropriate statistics and multivariate analysis for the evaluation of quantitative or qualitative characteristics in roses and their relationships.