Plant growth and flowering trend of landscaping roses under low maintenance and xeric conditions

The reported study is a step of a wider programme begun in 2002 and focused on the selection of rose shrubs well suited to a low maintenance regime without annual winter pruning, disease control and fertilization and especially, grown in xeric conditions. The study was carried out in the open field in an area located in North Italy, marked by a hot and dry summer with temperatures up to 45°C, yearly rainfall around 550 mm and a xeric 2.5 month long period from June to mid August. Floriferousness, flowering trend from May to October, number of flower flushes, canopy height and diameter of 131 cultivars was investigated throughout 5 years after planting and in the 6th year after mechanical, non-selective winter pruning. Performances of cultivars are described by plant area, the Flower Covering Index (FCI) and the Ornamental Index (OI), considering, on average, 5 and 6 year old plants. 45.4% of cultivars were characterized by a plant covered area from 0.5 to 1 m2, the FCI ranged from 0.5 to 1.0 in 48.1% of the cultivars and the OI was between 10 and 30 in 54.6% of the cultivars. ‘Alfabia’, ‘Altair’, ‘Aspirin’, ‘Avance’, ‘Fairy Queen’, ‘Heidetraum’, ‘Mirato’, ‘Polluce’, ‘Red Haze’, ‘Red Meidiland’, ‘Rody’, ‘Satina’, ‘Schneeflocke’ and ‘Sommermelodie’ stood out for both the high FCI and OI and, therefore, for the remarkable chromatic impact of plants at maximum flowering time and the prolonged flowering period, with several appreciable peaks.