ISSN 2756-3790
International Journal of Horticulture and Floriculture ISSN 2167-0455 Vol. 7 (7), pp. 001-006, July, 2019. © International Scholars Journals
Full Length Research Paper
Performance of 40 poinsettia cultivars grown under two different temperatures
Bruce L. Dunn1*, Carla Goad2 and Stephen Stanphill1
1Department of Horticulture and Landscape Architecture, Oklahoma State University, 358 Ag Hall, Stillwater, OK 74078, USA.
2Department of Statistics, Oklahoma State University 301 MSCS Building, Stillwater, OK 74078, USA.
Accepted 11 April, 2019
Abstract
This study evaluated forty poinsettia cultivars to determine which cultivars perform well under cool growing temperatures. Poinsettias were grown in separate greenhouses at temperatures of 20°C during the day and 17°C at night for cold production, or 25°C during the day and 22°C at night for warm production. Number of lateral shoots leading to inflorescences, number of bracts, canopy diameter, and stem diameter was determined. A significant (P= 0.03) cultivars by greenhouse temperature interaction existed for all parameters measured. Cultivars were then separated into classes based on greatest values for each trait. Poinsettia cultivars with the largest stem diameter in both warm and cold production systems included ‘39-02B’, ‘7-07’, ‘Classic™ White’, and ‘Enduring™ Red’. Poinsettia cultivars ‘HC-18B’, ‘Winter Blush’, ‘Cortez™ Burgundy, ‘Winter Rose™ Early Red’, ‘7-07’, ‘Silverstar™ Red’, ‘Topez’™, ‘Classic™ Red’, ‘Enduring™ White’, Novia™ Red’, Advent™ Red’, ‘Silverstar™ Marble’, and ‘1232’ had high bract numbers in both warm and cold production. Only one cultivar, '1266', produced a large number of lateral inflorescences in both production systems. Poinsettia cultivars ‘Classic™ White’, ‘Mira™ White’, ‘Novia™ Red’, Early ‘Orion™ Red’, ‘Mars’™ Pink’, and ‘Enduring™ Red’ had larger canopy diameters when grown in cool temperatures than under warmer conditions.
Key words: Greenhouse production, temperature, Euphorbia pulcherrima, plant physiology, plant architecture.