Evaluation of ground-cover roses in northern Italy.

摘要

Ground-cover roses combine the appeal and the beauty of rose flowers with the adaptability and tolerance of cover shrubs. Rose cultivars are usually bred in northern Europe, where growing conditions are dissimilar to those prevailing in southerly latitudes such as northern Italy. This latitude difference creates acclimatization problems for growers. The aim of this trial, set up at Fondazione Minoprio (Vertemate con Minoprio, Como), was to collect data concerning the performance of some widely-used ground-cover rose cultivars in Italy over a period of three years. In late spring 2003, 47 cultivars of ground-cover roses were planted; all the plants were mulched with a polypropylene sheet and covered with a 10.0 cm layer of pine bark. No irrigation, pruning and disease control were applied in order to simulate urban conditions. Height and ground covering percentage were measured every two months. Plant phenology, health status and bloom index (flower area per ground unit) were recorded weekly. The results presented are divided into the different flower colour classes. No differences emerged among white flower roses for ornamental value and ground cover capacity whilst yellow coloured roses suffered heavy defoliations due to black spot, with the exception of 'Sunny Rose'. Orange flowered roses were also susceptible to black spot, with the exception of 'Alfabia' that flowered continuously throughout the season. Among the pink roses, the cultivars 'Heidetraum' and 'Satina' produced the highest ornamental value when compared with the other cultivars. The most interesting red flower cultivar was 'Toscana' which was characterized by good disease tolerance, good ground covering capacity and by an appreciable dwarf size. In the purple-coloured group 'Knock Out' showed the best performance and ground covering ability; the cultivar was also characterized by long-lasting flowering (from May to November) and by an extended leaf persistence (until December). This trial confirmed that, in low-maintenance urban settings, disease tolerance is the most important feature, as affected plants show reduced growth and flowering, thus presenting a poor quality.