|Suh, Jeung Keun|
Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2007
Publication Date: 6/5/2007
Citation: Roh, M.S., Lee, A.K. and Suh, J.K. 2007. Induction of bulb maturity of Ornithogalum thyrsoides. Scienta Hort. doi:10.1016/j.scientia.2007.06.004. Interpretive Summary: Ornithogalum is a tunicated bulb native to the South-Western Cape of South Africa. New scales are formed after flower formation of the current year. When bulbs are harvested, all bulbs are not at the same physiological status because of differences in the growth rate and extent of foliage senescence. Some bulbs might still have green leaves that are senescing (“immature bulbs”) while leaves of other bulbs might have completely senesced (“mature bulbs”). These differences at harvest may contribute to the variations in growth and flowering responses following different bulb temperature treatments. The time of Ornithogalum bulb harvest in relation to forcing properties has not been investigated. Therefore, this study was initiated to understand and investigate the growth and flowering response of O. thyrsoides, ‘Chesapeake Starlight’ bulbs as influenced by the level of bulb maturity. The goal was to understand if bulb maturity can be induced by bulb storage temperatures (30oC and 10oC), and to investigate whether bulb maturity can be evaluated by the flowering response of bulbs to storage temperatures. Maturity as evaluated by flowering percentage and days from leaf emergence to flowering was induced by storing immature bulbs at 30o C for 6 wk. Immature bulbs can, therefore, be harvested for forcing as long as bulbs are treated longer than 6 weeks at 30o C. It is proposed that maturity can be correlated with the speed of flowering and bulbs can be harvested at an immature physiological state for forcing.
Technical Abstract: The influence of bulb maturity at bulb harvest on growth and flowering response of Ornithogalum thyrsoides Jacq. ‘Chesapeake Starlight’ was investigated. Experiments were designed to determine if bulb maturity can be induced by bulb storage temperatures and whether bulb maturity can be evaluated by flowering responses. Bulbs were potted after 0, 3, and 6 weeks of 30o C or 2 weeks of 10o C given either in the middle of 6 weeks of 30o C or at the end of 30o C. Mature bulbs, as compared to immature bulbs, took longer for leaves to emerge when control bulbs that did not receive any temperature treatment after harvest were planted upon harvest. Bulbs were considered “mature” when all leaves were senescent at harvest or “immature” when re-growing young roots and emerging young leaves were present at harvest. Leaf emergence of the immature bulbs was significantly earlier than that of the mature bulbs. Mature bulbs which received 30o C for 3 weeks (30o C/3 wk) flowered 31 days faster than immature bulbs and all bulbs flowered. Leaf emergence and flowering of mature and immature bulbs that receiving 30o C /6 wk or 2 weeks of 10o C in the middle of 6 weeks of 30o C (30o C /2 wk – 10o C /2 wk – 30o C /3 wk) did not differ from each other. Maturity can be induced by storing immature bulbs at 30o C/6 wk. Maturity, as evaluated by flowering percentage and days from leaf emergence to flowering, can be induced in O. thyrsoides. Immature bulbs can, therefore, be harvested for forcing as long as bulbs are treated longer than 6 weeks at 30o C/6 wk. It is proposed that maturity can be correlated with the speed of flowering and bulbs can be harvested at immature physiological state for forcing.