Paclobutrazol Substrate Drenches Control Growth of Nine Black-eyed Susan Cultivars
Our objective was to quantify the efficacy of paclobutrazol substrate drenches on growth of nine black-eyed Susan (Rudbeckia hirta) cultivars. Liners of ‘Autumn Colors’, ‘Cherokee Sunset’, ‘Cherry Brandy’, ‘Denver Daisy’, ‘Glowing’, ‘Happy’, ‘Indian Summer’, ‘Prairie Sun’, and ‘Sunny’ black-eyed Sus...
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| Format: | Article |
| Language: | English |
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American Society for Horticultural Science (ASHS)
2023-10-01
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| Series: | HortTechnology |
| Subjects: | |
| Online Access: | https://journals.ashs.org/horttech/view/journals/horttech/33/6/article-p527.xml |
| _version_ | 1797643335370801152 |
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| author | W. Tyler Rich W. Garrett Owen |
| author_facet | W. Tyler Rich W. Garrett Owen |
| author_sort | W. Tyler Rich |
| collection | DOAJ |
| description | Our objective was to quantify the efficacy of paclobutrazol substrate drenches on growth of nine black-eyed Susan (Rudbeckia hirta) cultivars. Liners of ‘Autumn Colors’, ‘Cherokee Sunset’, ‘Cherry Brandy’, ‘Denver Daisy’, ‘Glowing’, ‘Happy’, ‘Indian Summer’, ‘Prairie Sun’, and ‘Sunny’ black-eyed Susan were transplanted into 6.5-inch-diameter plastic containers (2 qt) filled with a commercial soilless peat-based substrate. After 16 days, six single-plant replicates received a substrate drench of 5-fl-oz aliquots of solutions containing deionized water [0 mg·L−1 paclobutrazol (control)] or 2.5, 5, 10, or 20 mg·L−1 paclobutrazol (0, 0.375, 0.75, 1.5, and 3.0 mg/pot). Paclobutrazol drenches of 2.5 to 20 mg·L−1 significantly influenced plant height, plant diameter, growth index (GI), and shoot dry weight (SDW) of all black-eyed Susan cultivars, although the magnitude of response to paclobutrazol substrate drench concentration varied with cultivar. For most cultivars, GI, an integrated measurement of height and diameter, was suppressed as paclobutrazol substrate drench concentrations increased from 2.5 to 20 mg·L−1, resulting in plants that were 30% to 43% smaller than untreated plants. Increasing paclobutrazol substrate drench concentrations from 2.5 to 20 mg·L−1 limited SDW of each cultivar differently, although plants were 5% to 59% smaller at 20 mg·L−1 paclobutrazol than untreated plants. Time to flower for ‘Autumn Colors’, ‘Cherry Brandy’, ‘Happy’, ‘Indian Summer’, and ‘Prairie Sunset’ was unaffected by any paclobutrazol substrate drench concentration; however, concentrations of ≤10 mg·L−1 paclobutrazol are suggested for ‘Cherokee Sunset’, ‘Denver Daisy’, ‘Glowing’, and ‘Sunny’, as higher concentrations delay flowering. Our results indicate that growers can attain growth control with substrate drenches containing 5 to 10 mg·L−1 paclobutrazol during greenhouse black-eyed Susan production without delaying flowering. |
| first_indexed | 2024-03-11T14:13:20Z |
| format | Article |
| id | doaj.art-8a79b25ce1914edab3c241e0ca8ebbc0 |
| institution | Directory Open Access Journal |
| issn | 1943-7714 |
| language | English |
| last_indexed | 2024-03-11T14:13:20Z |
| publishDate | 2023-10-01 |
| publisher | American Society for Horticultural Science (ASHS) |
| record_format | Article |
| series | HortTechnology |
| spelling | doaj.art-8a79b25ce1914edab3c241e0ca8ebbc02023-11-01T16:12:23ZengAmerican Society for Horticultural Science (ASHS)HortTechnology1943-77142023-10-01336https://doi.org/10.21273/HORTTECH05290-23Paclobutrazol Substrate Drenches Control Growth of Nine Black-eyed Susan CultivarsW. Tyler Rich0W. Garrett Owen1 Department of Horticulture and Crop Science, The Ohio State University Department of Horticulture and Crop Science, The Ohio State UniversityOur objective was to quantify the efficacy of paclobutrazol substrate drenches on growth of nine black-eyed Susan (Rudbeckia hirta) cultivars. Liners of ‘Autumn Colors’, ‘Cherokee Sunset’, ‘Cherry Brandy’, ‘Denver Daisy’, ‘Glowing’, ‘Happy’, ‘Indian Summer’, ‘Prairie Sun’, and ‘Sunny’ black-eyed Susan were transplanted into 6.5-inch-diameter plastic containers (2 qt) filled with a commercial soilless peat-based substrate. After 16 days, six single-plant replicates received a substrate drench of 5-fl-oz aliquots of solutions containing deionized water [0 mg·L−1 paclobutrazol (control)] or 2.5, 5, 10, or 20 mg·L−1 paclobutrazol (0, 0.375, 0.75, 1.5, and 3.0 mg/pot). Paclobutrazol drenches of 2.5 to 20 mg·L−1 significantly influenced plant height, plant diameter, growth index (GI), and shoot dry weight (SDW) of all black-eyed Susan cultivars, although the magnitude of response to paclobutrazol substrate drench concentration varied with cultivar. For most cultivars, GI, an integrated measurement of height and diameter, was suppressed as paclobutrazol substrate drench concentrations increased from 2.5 to 20 mg·L−1, resulting in plants that were 30% to 43% smaller than untreated plants. Increasing paclobutrazol substrate drench concentrations from 2.5 to 20 mg·L−1 limited SDW of each cultivar differently, although plants were 5% to 59% smaller at 20 mg·L−1 paclobutrazol than untreated plants. Time to flower for ‘Autumn Colors’, ‘Cherry Brandy’, ‘Happy’, ‘Indian Summer’, and ‘Prairie Sunset’ was unaffected by any paclobutrazol substrate drench concentration; however, concentrations of ≤10 mg·L−1 paclobutrazol are suggested for ‘Cherokee Sunset’, ‘Denver Daisy’, ‘Glowing’, and ‘Sunny’, as higher concentrations delay flowering. Our results indicate that growers can attain growth control with substrate drenches containing 5 to 10 mg·L−1 paclobutrazol during greenhouse black-eyed Susan production without delaying flowering.https://journals.ashs.org/horttech/view/journals/horttech/33/6/article-p527.xmlfloriculturegreenhouse productionherbaceous perennialplant growth retardantrudbeckia |
| spellingShingle | W. Tyler Rich W. Garrett Owen Paclobutrazol Substrate Drenches Control Growth of Nine Black-eyed Susan Cultivars HortTechnology floriculture greenhouse production herbaceous perennial plant growth retardant rudbeckia |
| title | Paclobutrazol Substrate Drenches Control Growth of Nine Black-eyed Susan Cultivars |
| title_full | Paclobutrazol Substrate Drenches Control Growth of Nine Black-eyed Susan Cultivars |
| title_fullStr | Paclobutrazol Substrate Drenches Control Growth of Nine Black-eyed Susan Cultivars |
| title_full_unstemmed | Paclobutrazol Substrate Drenches Control Growth of Nine Black-eyed Susan Cultivars |
| title_short | Paclobutrazol Substrate Drenches Control Growth of Nine Black-eyed Susan Cultivars |
| title_sort | paclobutrazol substrate drenches control growth of nine black eyed susan cultivars |
| topic | floriculture greenhouse production herbaceous perennial plant growth retardant rudbeckia |
| url | https://journals.ashs.org/horttech/view/journals/horttech/33/6/article-p527.xml |
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