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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Publications at this Location » Publication #185852
Title: INFLORESCENCE DEVELOPMENT AND FLOWERING OF ORNITHOGALUM THYRSOIDES HYBRID AS AFFECTED BY MANIPULATION DURING BULB STORAGE

Author
item Roh, Mark
item HONG, DAE-KI - AG RES AND EXT SER, KOREA

Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2007
Publication Date: 6/29/2007
Citation: Roh, M.S. and Hong, D-K. 2007. Inflorescence development and flowering of Ornithogalum thyrsoides hybrids by temperature manipulatin during bulb storage. Scienta Hort. 113:60-69.

Interpretive Summary: The effects of seasonal temperature changes on the growth and development of most flower bulbs must be understood in order to understand the complete life cycle. In general, temperature is the major environmental factor that influences the flowering processes from flower initiation to development in bulbous plants. Floral initiation and development requirements for O. dubium and new O. thyrsoides hybrids are not yet available. Once floral initiation is completed by high-temperature, a low-temperature treatment or pre-cooling temperature further accelerates differentiation and or maturation of the floral parts of many bulbs. Specific requirements for the duration of high and warm temperature treatments and the pre-cooling temperatures for Ornithogalum have not been determined and inflorescence and floret development has not been well documented. Therefore, these experiments were initiated to study and document the development of the inflorescence and florets and growth and flowering response as influenced by the bulb size and bulb storage temperature treatments given to O. thyrsoides, ‘Chesapeake Starlight’. To produce two or more inflorescences from one bulb, we recommend treating bulbs at 10oC for 3 to 4 weeks or 13o/3W, although flowering is somewhat delayed. Scanning electron micrographs are useful to study the effect of various storage conditions on the development of inflorescences and of individual florets and to further develop precise treatment temperatures and durations to shorten the pre-treatment period of bulbs after harvest.

Technical Abstract: The growth and flowering response of Ornithogalum thyrsoides, ‘Chesapeake Starlight’ as influenced by bulb size and storage temperature treatments were investigated. Development of inflorescences and florets as influenced by bulb storage temperature was also followed using scanning electron microscopy (SEM). Three experiments were carried out. Development of inflorescences and florets were studied using SEM (Expt. 1). The shoot apex of the bulb is vegetative at harvest and bulbs should be stored dry at 28o - 30oC for six weeks (28-30o/6W) for rapid inflorescence development. Once the shoot apex becomes reproductive, the bulbs are then stored at 20o/4W, and finally at 10o/8W. At the end of the 20oC treatment when root primordia are clearly visible from the basal plate and the scape of the first inflorescence is clearly formed, bulbs are then treated at 10oC. Flowering was also accelerated and only one inflorescence was produced when bulbs were stored at 10o/6W. A sequential treatment of 30o/6W– 16o/6W– 10o/6W ensured a longer flower stem and accelerated flowering. However, only one inflorescence is produced as shown by SEM. To produce two or more inflorescences from one bulb, we recommend treating bulbs at 10oC for 3 to 4 weeks or 13o/3W, although flowering is somewhat delayed. Scanning electron micrographs are useful to study the effect of various storage conditions on the development of inflorescences and of individual florets and to further develop precise treatment temperatures and durations to shorten the pre-treatment period of bulbs after harvest.