Ornamental geophytes comprise a large and diverse group of plants characterized by underground storage organs that serve the obvious function of reserve storage and subsequent supply during early stages of shoot growth. Relative to many agronomic and horticultural crops, the fundamental physiological bases of carbon metabolism, partitioning, and utilization in geophytes are unclear. One reason is diversity in organ morphology (bulb, corm, tuber, root, rhizome, etc.), storage carbohydrate (starch, fructan, glucomannan, etc.), and growth habit (e.g., synanthous vs. hysteranthous flowering). Knowledge of factors that control accumulation and mobilization of carbohydrate reserves may lead to manipulations that considerably improve the quality and culture of these crops. We are utilizing a variety of techniques and experimental systems to study selected internal and external controls or influences on geophyte carbohydrate metabolism and partitioning. Specific examples to be discussed include bulb storage temperature effects on starch and fructan metabolism in Tulipa, effects of carbon source and dormancy breaking treatments on starch and glucomannan metabolism in in vitro-grown Lilium bulblets, photoperiod control of fructan accumulation in Dahlia seedlings, and biochemical and molecular features of soluble and wall-bound invertases in developing Lilium longiflorum flower buds.
William B. Miller, Anil P. Ranwala, Garry Legnani, Merel Langens-Gerrits, Geert-Jan de Klerk, Johannes Eckelmann, and Michael Ernst
Carlos De la Cuadra, Alexis K. Vidal, and Leví M. Mansur
rainfall (>15 mm) normally occurs during the phenomena of El Niño–Southern Oscillation, and as a consequence, the emergence of more than 200 species of annual plants and geophytes occur, including Z. compacta ( Gutiérrez, 2008 ). Fig. 3. Climograph of
Carlos De la Cuadra, Alexis K. Vidal, Patricia Peñaloza, Leví Mansur, and Carlos Huenchuleo
, where unusually high rainfall (≥15 mm) leads to the emergence of more than 200 species of annual and geophyte plants, including Z. elegans ( Gutiérrez, 2008 ; Vidiella et al., 1999 ). Zephyra elegans may have survival strategies to take advantage of
A. A De Hertogh, C. Noone, and A. Lutman
Much information has been accumulated on various aspects of ornamental geophytes. This knowledge has been published in research articles and bulletins, books, extension publications, etc. Thus, it is scattered and not easily accessible. The Geophyte TM software program was developed to aid in information access and transfer. It has been designed for IBM compatible systems. There are 7 major parts in each database. They are: 1- General Aspects (species origin, botanical classification, common names, etc), 2- Flowering Requirements, 3- Production Information (production countries and acreage, major commercial cultivars, production methods, etc.), 4- Gardening Information (soil types, light, planting info, cultivar performance data, etc.), 5- Forcing Information (commercial cut flowers, potted plants, homeowner forcing), 6- References, and 7- In-House Information, a slot allowing the user to insert specific information on the genera provided.
Resource partitioning and plant storage components are important factors that influence the productivity and profitability of geophyte species produced as floral crops. We determined that inoculation with arbuscular mycorrhizal fungi (AMF) can alter different plant characteristics affecting productivity and quality of bulb and cut flower production of several floral geophytes including Brodiaea laxa, Zephyranthes sp., Sparaxis tricolor, Freesia × hybrida, Zantedeschia sp., and Canna sp. Plant growth, flower production, bulb/corm/tuber (bulb) production and composition were measured for two growth cycles after inoculation with Glomus intraradices. In general, shoots and flowers on plants inoculated with AMF emerged earlier than shoots and flowers on non-inoculated plants for species that produced most of their leaf area prior to flower emergence. However for species that produced leaves throughout the growth cycle or large flowers early in the growth cycle, AMF inoculation delayed shoot emergence and flower emergence. Many species that exhibited an earlier flower emergence or produced more flowers in response to AMF inoculation also produced smaller daughter bulbs and more offsets than non-inoculated plants. Across all species, the concentrations and contents of several storage components (Zn, S, and N, amino acids, and carbohydrates) that influence bulb quality were increased by AMF inoculation. Changes in partitioning between bulb and flower production resulting from AMF inoculation altered important aspects of commercial geophyte production for flowers or bulbs. AMF-induced increases in mineral uptake and resource storage are also related to aspects of quality important in the production of vegetative propagates.
Luis Humberto Escobar Torres, Eduardo Alejandro Olate Muñoz, Miguel Jordan, and Marlene Gebauer
Callus induction (CI) and later shoot induction (SI) were studied in Leucocoryne purpurea, a native and endemic Chilean geophyte species. Basal leaf portions (BL), bulb basal plate (BP), and root tips (RT) from in vitro plants were used as explants. Treatments for CI included all three explants and media containing different sources and concentrations of auxins and cytokinins as plant growth regulators (PGRs). Plant material was initiated on MS basal medium (Murashige and Skoog, 1962), supplemented with vitamins, 30 g·L-1 sucrose, 6.0 g·L-1 agar and pH adjusted to 5.7 before autoclaving. The experiments were carried on a growth chamber at 24 ± 1.5 °C. CI cultures were maintained in darkness for 16 weeks, and SI for 12 weeks in a 16-hour photoperiod. BL and RT explants did not respond to any of the CI treatments. BP explants cultured on MS basal medium without PGRs also did not produce any callus. The average frequency of callus induction for BP was 78% and the average fresh weight of callus was 10.06 g/explant after 16 weeks of culture. Best treatment for CI was BP cultured on 4.52 μm 2,4-dichlorophenoxyacetic acid (2,4-D) in combination with 0.45 μm 6-benzyladenine (BA), when they were compared to 2,4-D alone or picloram as auxin source. After 16 weeks of culture, calli were transferred to SI medium, supplemented with three different concentrations of thidiazuron (TDZ), either intact or subdivided (150 mg/explant). SI treatments had a greater and significant response when the callus came from a CI medium containing auxin and cytokinin combined, in comparison to those coming from a CI medium containing auxins only.
Amalia Barzilay, Hanita Zemah, Rina Kamenetsky, and Itzhak Ran
The life cycle and morphogenesis of the floral shoot of Paeonia lactiflora Pallas cv. Sarah Bernhardt were studied under Israeli conditions. The renewal buds for the following year originate on the underground crown, at the base of the annual stems. Bud emergence begins in early spring. Stems elongate rapidly and reach heights of 50-70 cm in 60-70 days. Flowering begins in April and continues until the end of May. After flowering, the leafy stems remain green until September-October, when the leaves senesce, and the peony plant enters the “rest” stage for 3-4 months. The new monocarpic shoot initiated in the renewal bud at the end of June with the formation of the first leaf primordia and continued to increase in size until February. During summer, the renewal buds remain vegetative. The apical meristem ceases leaf formation after senescence of the aboveground shoots in the fall. During September, the apical meristem of the renewal buds reaches the generative stage and achieves the form of a dome, but remains undifferentiated. In October, floral parts become visible. Floral differentiation is terminated at the beginning of December. Floral initiation and differentiation of peony do not require low temperatures. Morphological development and florogenesis were similar to other geophyte species with an annual thermoperiodic life cycle.
Jaser A. Aljaser and Neil O. Anderson
treatment ( Aljaser, 2020 ) All gladiolus species are geophytes with corms (compressed stems) as underground storage organs ( De Hertogh and Le Nard, 1993 ). In commercial production, gladioli are planted as mature (3–5 years old) corms ( Dole and Wilkins