Miltoniopsis orchids have appealing potted-plant characteristics, including large, fragrant, and showy pansylike flowers that range from white and yellow to shades of red and purple. Scheduling orchid hybrids to flower on specific dates requires knowledge of how light and temperature regulate the flowering process. We performed experiments to determine whether a 9- or 16-h photoperiod [short day (SD) or long day (LD)] before vernalization and vernalization temperatures of 8, 11, 14, 17, 20, or 23 °C under SD or LD regulate flowering of potted Miltoniopsis orchids. Flowering of Miltoniopsis Augres `Trinity' was promoted most when plants were exposed to SD and then vernalized at 11 or 14 °C. Additional experiments were performed to determine how durations of prevernalization SD and vernalization at 14 °C influenced flowering of Miltoniopsis Augres `Trinity' and Eastern Bay `Russian'. Plants were placed under SD or LD at 20 °C for 0, 4, 8, 12, or 16 weeks and then transferred to 14 °C under SD for 8 weeks. Another set of plants was placed under SD or LD at 20 °C for 8 weeks and then transferred to 14 °C with SD for 0, 3, 6, 9, or 12 weeks. After treatments, plants were grown in a common environment at 20 °C with LD. Flowering of Miltoniopsis Augres `Trinity' was most complete and uniform (≥90%) when plants were exposed to SD for 4 or 8 weeks before 8 weeks of vernalization at 14 °C. Flowering percentage of Miltoniopsis Eastern Bay `Russian' was ≥80 regardless of prevernalization photoperiod or duration. This information could be used by greenhouse growers and orchid hobbyists to more reliably induce flowering of potted Miltoniopsis orchids.
Roberto G. Lopez and Erik S. Runkle
Erika Szendrák and Paul E. Read
The temperate native terrestrial orchids are endangered species. Their propagation from seeds poses specific problems. It is well known that orchid seeds are devoid of endosperm and in nature they need microscopic fungi in a symbiotic relationship for germination. We developed a successful asymbiotic in vitro culture method for germinating seeds of several temperate orchid species and for maintaining the cultures of young plantlets. The medium used for both germination and seedling culture was a modified FAST medium. Seeds were surface-disinfested for 10 minutes in a 10% calcium hypochlorite solution. After sowing, the cultures were kept under dark condition at 10–12°C for 4 weeks. After that the cultures remained in the dark, but the temperature was raised to 25–26°C until germination occurred. Thereafter cultures required alternating seasonal temperatures: 25–26°C from the beginning of April to the end of September and 17–19°C from October to March. For the development of the young plantlets natural dispersed light and prevailing day-length was favorable. After 2 years of aseptic culture they were suitable for transfer ex vitro. Different stages of seed germination and plant development were observed using a scanning electron microscope and will be included in this presentation. Further observation of the effects of different environmental factors is currently under investigation.
Cheng-Jung Hu, Nean Lee, and Yung-I Lee
The dancing-lady orchid, Oncidium Sw., and its relative genera within subtribe Oncidiinae native to Central and South America are important ornamental orchids in the horticultural market ( Chase, 1997 ). Because of the long-lasting and bright
Matthew G. Blanchard* and Erik Runkle
The commercial production of potted flowering orchids has increased tremendously in the past decade, and is now the second most valuable potted flowering crop in the United States. Phalaenopsis spp. comprise a large percentage (75% to 85%) of the potted orchid sales in the U.S. due to their long flower life and ease of scheduling to meet specific market dates. Constant air temperatures above ≈26 °C inhibit flowering of most Phalaenopsis hybrids, and a 25/20 °C day/night temperature regimen is used commercially to induce flowering. However, the relative promotion of flowering by constant versus fluctuating day/night cool temperatures (<25 °C) has not been well described. Phalaenopsis Miva Smartissimo × Canberra `450' and Brother Goldsmith `720' were grown at constant temperatures of 14, 17, 20, 23, 26, and 29 °C, and day/night temperatures of 20/14, 23/17, 26/14, 26/20, 29/23, and 29/17 °C;. Plants were grown in glass greenhouses with a constant photoperiod of 12 h, and shading was provided so that the maximum instantaneous irradiance was ≤150 μmol·m-2·s-1. After 6 weeks at the various temperature setpoints, ≥80% of plants of both cultivars had VI when grown at a constant 17, 20, or 23 °C, and at the 23/17 °C day/night regimen. None of the plants were reproductive within 6 weeks when grown at a constant 26 or 29 °C, or at the 26/14, 26/20, 29/17, or 29/23 °C day/night temperature setpoints. Therefore, temperature during the day and night both influence flowering of these two Phalaenopsis orchid hybrids.
The apical meristems of Calanthe orchid embryos were exposed to 1 mg/ml pBI-121 DNA in an electric field. pBI-121 contains the GUS marker gene glucoronidase under the control of the 35 S cauliflower mosaic virus promoter. A pipette containing 0.3% agarose and acetate buffer containing the DNA was placed on one end of the embryo; while the opposite end was in contact with a pipette containing only buffer and agarose. Uptake of the DNA into the meristem was monitored by 4′6-diamidino-2-phenylindole (DAPI) fluorescence. Optimal uptake occurred after 10 min of electrophoresis at 10 volts and 0.5 milliamps. Under these conditions, 55% of the embryos survived the treatment and 57% of those which survived were transformed as measured by GUS-positive staining. Leaves from 6 month old plants which developed from the transformed embryos expressed specific patterns of GUS staining.
Margaret From and Paul E. Read
Platanthera praeclara, commonly called western prairie fringed orchid, is a showy forb native to seven states and one Canadian province. The species had resisted previous attempts at propagation. Small, isolated populations in the sandhills region of western Nebraska are disjunct and visitation by natural pollen vectors appears to be in decline. Modern cultivation practices and other habitat encroachment factors, including urban development, recreational activities, and natural fluctuations in seasonal water availability all have the potential to exert pressure on current populations. Federal and state permits have allowed a limited hand-pollination study to be conducted on federal land. Hand-pollinated plants showed a greater fruit production compared to control plants receiving no human pollination assistance. Germination studies were conducted using aseptic in vitro techniques. The microscopic seeds possess testa that are extremely hard and resistant to liquid absorption, which presents challenges to germination in vitro. These challenges will be discussed. Alternating cold treatments with room temperatures appeared necessary to promote protocorm development after germination. Three media tested produced varying germination responses. Juvenile plants produced through micropropagation can offer propagules for possible future reintroduction efforts of this protected species.
Letitia Quay, Jen A. McComb, and Kingsley W. Dixon
Seeds of two Australian terrestrial orchid species (Caladenia latifolia R.Br. and Diuris magnifica D. Jones) were germinated in a potting mix of Allocasuarina fraseriana (Miq.) L. Johnson leaf mulch and perlite (1:1). The potting mix was irradiated (7 Gy for 14 hours), steam pasteurized (70C for 30 minutes) or nontreated, and inoculated with the appropriate mycorrhizal fungus for each species, a sterile red fungus (SRF), or both. Protocorm formation and green shoots were evident at 8 and 10 weeks, respectively, after seed sowing. The highest mean number of seedlings was 84 for C. latifolia and 234 for D. magnifica per 270-ml container in pasteurized potting mix inoculated with mycorrhizal fungi and SRF. Shoots were longest after 20 weeks (28 mm for C. latifolia and 52 mm for D. magnifica, respectively) in pasteurized potting mix inoculated with mycorrhizal fungi only. Germination was absent in control treatments without mycorrhizal fungi; with SRF only; or in nonsterile potting mix with mycorrhizal fungi, SRF, or both.
Martín Mata-Rosas and Víctor M. Salazar-Rojas
Mexico has ≈1200 of the 25,000 orchid species that have been described ( Dixon et al., 2003 ); 40% of these are endemic species ( Espejo and López, 1998 ). Several species are endangered as a direct or indirect result of two human activities
Gabriela Verdugo Ramírez, Mauricio Cisternas Baez, Ursula Steinfort, Hermine Vogel, and Rosa Cueto-Ewoldt
production is consumed domestically. Orchids have become one of the largest commodities in the international cut flower and ornamental plant market, with an international trade value of U.S. $504 million in 2012, in which the genera Cymbidium , Dendrobium
Woei-Jiun Guo, Yu-Zu Lin, and Nean Lee
Phalaenopsis orchids have become one of the most valuable potted ornamental plants around the world. According to the U.S. Department Agriculture’s (USDA’s) Floriculture Crops Summary, potted orchids account for $191 million in wholesale revenue in