| dc.description.abstract | Spent flower removal is commonly practiced on remontant garden roses as a landscape management tool to hasten rebloom. To study the effects of spent flower removal on the reblooming and branching architecture of garden roses, four Shrub rose cultivars were established in the field in February 2019 and treatments were started in June 2019 at Somerville and Overton with the same treatments and controls in each cultivar. Spent flower removal had no effect on the days to rebloom between flushes of flowering. ‘Belinda’s Dream’ had the longest reblooming period. The current season growth and primary shoot number were not affected by spent flower removal. Plants in Somerville exhibited a higher number of secondary and tertiary shoots than in Overton regardless of cultivar and more quaternary shoots on some cultivars than those in Overton. This is likely attributable to the longer growing season in Somerville than in Overton.
An important aspect of heat tolerance of ornamental plants is the response of the flowers to high temperature. Commercial garden rose cultivars with buds 4 mm in diameter were exposed to temperatures of 36, 40, or 44 ˚C for durations of 1, 3, or 5 h in factorial combination in a heat chamber and compared to untreated controls to determine the effects of heat on floral parameters including petal number, flower diameter and flower dry weight when flowers were fully open. The number of treatments different from the control determined using Dunnett’s test and the parameters affected by the temperature × duration factors as determined by ANOVA were used to categorize the cultivars studied.
Dry weight was the most sensitive parameter measured. ‘CHEwnicebell’ and ‘ZLEMarianne Yoshida’ were categorized as Heat Sensitive cultivars, ‘Winnipeg Parks’ was categorized as Moderately Heat Susceptible. ‘Morden Blush’, ‘Meipeporia’ and ‘RADrazz’ was considered as Moderately Heat Tolerant cultivars. ‘RADtko’ and ‘RIPhud’ were not affected by the heat treatments and were categorized as Heat Tolerant cultivars. Exposure of plants with buds 4 mm in diameter to 44 ˚C for 3 or 5h was the most effective treatment for determining floral heat tolerance for the cultivars studied. | |
