Comparative assessment of different rose cultivars under environmental conditions in central Transylvania, Romania

Abstract

Despite the abundance of rose varieties, it is necessary to create and use new genotypes to improve the appearance of green spaces and meet the demands of society, as well as to ensure their response to environmental variables and climate change. To assess the overall value and flower quality of several Romanian and foreign varieties under the ecological circumstances of Northwest Romania, 14 rose varieties from the shrub and floribunda groups were examined. The study identified notable variations among the cultivars for plant growth, foliage, flowers, and their susceptibility to the three primary fungal diseases (black spot, powdery mildew, and rust) prevalent in the study area. Additionally, the study identified the cultivars with proper resilience to frost during the five-year investigation period, particularly after the cold winters. New varieties obtained at HRS Cluj-Napoca, such as Cristiana, Pasiune mov, Maria-Cristina and Splendid, and international varieties such as Fisherman's Friend, Bonica and Mirato, stood out for their decorative quality and attractive floral elements. Some of these varieties have also been considered potential parents for disease and frost resistance in new hybridization projects. Broad-sense heritability data for the quantitative variables under investigation, as well as multivariate analyses, provided useful information for new rose breeding programs. The comparison of quantitative and qualitative assessments of important decorative traits for the roses, together with proper statistical calculation processes to assure their validity and trustworthiness, enabled the development of hypotheses or working models that can improve rose breeding efficiency.