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Induction of bulb maturity of Ornithogalum thyrsoides
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 with all senesced leaves at harvest were considered “mature” or with emerging young leaves and re-growing young roots were considered “immature”. Bulbs were potted after 0, 3, and 6 weeks of 30 °C or 2 weeks of 10 °C given either in the middle or at the end of 6 weeks of 30 °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. Leaf emergence of the immature bulbs was significantly earlier than that of the mature bulbs. Mature bulbs which received 30 °C for 3 weeks (30 °C/3 week) flowered 31 days faster than immature bulbs and all bulbs flowered. Leaf emergence and flowering of mature and immature bulbs that received 30 °C/6 weeks or 2 weeks of 10 °C in the middle of 6 weeks of 30 °C (30 °C/2 weeks–10 °C/2 week–30 °C/3 weeks) did not differ from each other. Maturity can be induced by storing immature bulbs at 30 °C/6 weeks. 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 later forcing as long as bulbs are treated with 30 °C/6 weeks. It is proposed that maturity can be correlated with the speed of flowering and bulbs can be harvested at immature physiological state for forcing. Postharvest high-temperature treatment can be used to force immature bulbs that were harvested before the senescence of the leaves.
... One of the factors limiting the commercial production is high sensitivity to both viral and bacterial pathogens (Byther andChastagner 1993, Luria et al. 2002) which is associated with the vegetative propagation from bulbs. Alternatively, tissue culture techniques for propagation of some Ornithogalum species including O. dubium and O. thyrsoides have been successfully applied in the past ( Hussey 1976, Ziv and Lilien-Kipnis 2000, Kariuki and Kako 2003, Roh et al. 2007, Ozel et al. 2008. Still, keeping disease-free propagation material and increasing the propagation rates of desired genotypes are a continuous challenge in Ornithogalum production (Naik and Nayak 2005). ...
... Initial morphogenic cell clusters of both plant species were generated from the calli by gently separating it into roughly 2 mm fragments. The fragments were placed in 20 cm 3 of liquid Murashige and Skoog (1962;MS) medium supplemented with 0.1 mg dm-3 1-naphthaleneacetic acid (NAA), 2 mg dm-3 6-benzylaminopurine (BAP) and 3 % sucrose (M-206) in 120 cm 3 Erlenmeyer flasks. The pH of the media was adjusted to 5.6-5.7 before autoclaving at 121 °C, for 20 min (Cohen et al. 2004). ...
Benzothiadiazole (BTH) is a structural analogue of salicylic acid (SA) which is widely recognized for its role in elicitation of systemic acquired resistance in a broad range of plant species. Here, BTH was applied to cell cultures of the bulbous ornamental plants Ornithogalum dubium and O. thyrsoides, showing a strong effect on rates of differentiation and morphogenesis. Morphogenic cell clusters in liquid Murashige and Skoog (MS) medium containing 1-naphthaleneacetic acid (NAA) and 6-benzylaminopurine (BAP) were used for all treatments. The calluses were washed thoroughly and activated with increasing concentrations of BTH. Following the induction, calli were grown on a solid MS medium without growth regulators (MS) or on a comparable media with NAA and BAP (M-206). The calli treated with BTH displayed a dose dependent increase in formation of meristematic centres followed by enhanced shoot formation compared to controls. Microscopic analyses revealed increased differentiation to cell organelles and a strengthening of the cell wall. A stronger response to BTH was observed in MS than in M-206 medium. A similar effect on calli differentiation was obtained by three weeks darkness followed by light exposure. The dark/light positive effect on differentiation was further augmented by BTH in a synergistic fashion. It is suggested that BTH enhances the rates of morphogenesis in Ornithogalum cultures by triggering a plant regulator-like activity.
... Ornithogalum thyrsoides Jacq. (Roh et al., 2007) (Horimoto et al., 2011;Roh et al., 2004). ...
Background and objective: The objective of this study was to produce Asiatic hybrid lily with more than two flowers in one year starting from bulbils. This study was to force 'Beni no Mai' bulbils influenced by harvesting date, flower bud removal, and temperature manipulation and to evaluate dormancy and maturity by nuclear magnetic resonance imaging (NMRI) and carbohydrates analysis.Methods: In experiment 1, bulbils were harvested at 0-30 days after anthesis (DAA), and were divided into 7 stages. And, soluble monosaccharides and monosaccharide constituents of bulbils were analyzed. In experiment 2, flower buds of plants that flowered on 21 April were not removed or removed on 1, 13, and 25 April. Bulbils harvested were divided into four groups and planted after cold treatment. In experiment 3, bulbils received a sequential temperature (SEQ CD) treatments for three weeks at 2.5, 5.0, and 7.5°C, 1 week at 10, 12.5, and 15°C, and 3 weeks at 2.5, 5.0, and 7.5°C. In experiment 4, bulbils were harvested 0-70 DAA, and were subjected to spin-spin lattice relaxation time by NMRI.Results: The bulbils harvested at 30 DAA produced two flowers within 282 days, and were better in growth. The bulbils harvested at 30 DAA showed higher concentration of soluble glucose and lower concentration of non-cellulosic neutral glucose. Growth of bulbils removed flower buds before flowering were better than those of bulbils that flower bud was removed at anthesis and 13 Apr. However, the number of flowers of bulbils harvested from plants removed flower buds on 1 Apr. were less than 2. The SEQ CD treatment of 7.5°C/3W-15°C/1W-5°C/3W in bulbils could produce the plants with 2.2 flowers within 300 days after planting. When bulbils were harvested at 0-28 DAA, yellow color corresponding to T2 relaxation time of 15-20 ms was dominant, and bulbils harvested at 56-70 DAA showed T2 relaxation time of 35-50 ms and 50-100 ms.Conclusion: Considering the results of soluble carbohydrate content and T2 relaxation time of bulbils, it was found that the bulbils had a shallower dormancy and were more mature at 30-42 DAA than before 28 DAA. Also, when these bulbils were planted after SEQ CD treatment at 7.5°C/3W-15°C/1W-5°C/3W, plants with two or more flowers could be produced within one year.
... One of the factors limiting the commercial production is high sensitivity to both viral and bacterial pathogens (Byther and Chastagner 1993, Luria et al. 2002) which is associated with the vegetative propagation from bulbs. Alternatively , tissue culture techniques for propagation of some Ornithogalum species including O. dubium and O. thyrsoides have been successfully applied in the past (Hussey 1976, Ziv and Lilien-Kipnis 2000, Kariuki and Kako 2003, Roh et al. 2007, Ozel et al. 2008). Still, keeping disease-free propagation material and increasing the propagation rates of desired genotypes are a continuous challenge in Ornithogalum production (Naik and Nayak 2005). ...
The objective of this study was to investigate the optimum concentration of plant growth regulators for explants cultured in vitro to produce inflorescences of Ornithogalum thyrsoides ‘Chesapeake Starlight’ forcing directly from in vitro propagules in one year. Two sizes of explants (2 × 2 and 2 × 4 mm) were cultured on a Murashige and Skoog (MS) medium supplemented with 0, 1.35, 2.7, or 5.4 μM 2-(1-Naphthyl)acetic acid (NAA) and with 0, 3.3, 6.6, or 13.2 μM N-(phenylmethyl)-7H-purin-6-amine (BA); and with 0, 0.675, 1.35, or 2.7 μM NAA and with 0, 2.2, 4.4, or 8.8 μM BA at 21 °C. Explants propagated in a Petri dish were directly transplanted to 6.3 cm pots as a clump without separating plantlets from the explant (propagule), then transplanted to a tray, and forced at 16.5/16 °C (day/night). The number of days to flowering from the first and second scape (FS and SS, respectively) from the first, second, or third plantlets (FP, SP, and TP, respectively) formed from the clump of one explant was counted from the date of transplanting to pots, and scape length and diameter were recorded. Criteria for high-quality cut flowers were (1) flowering around 200–215 days in FS/FP and 230–245 days in SS/FP with a flowering rate of 90–100% in FS/FP and 70–80% in SS/FP, (2) a scape length greater than 50 cm in FS/FP and greater than 55 cm in SS/FP, and (3) a scape diameter above 8 mm. Based on these criteria, the optimum concentrations of NAA and BA were determined. High quality O. thyrsoides cut flowers flowering after 195–201 days, a flowering rate of 78–100% in FS/FP, and three or four scapes of SS/FP and FS/SP can be successfully produced from 2 × 2 mm or 2 × 4 mm explants cultured in MS medium supplemented with 1.35–2.7 μM NAA and 4.4–6.6 μM BA. This demonstrates that quality cut flowers can be produced in less than one year without separating plantlets grown in vitro as one clump which saves labor. Developing two scapes from each of two first plantlets may suggest competition for reserves of metabolites/endogenous plant hormones.
We determined the effects of preplant storage temperature and duration and greenhouse growing temperature on the growth and flowering of four cultivars of potted Ornithogalum representing Ornithogalum dubium (three cultivars) and Ornithogalum thyrsoides (one cultivar) originating from Israeli breeding. Bulbs were stored at five temperatures for 1 to 4 weeks before planting. Within the range of 9 to 27 degrees C, lower preplant storage temperature resulted in earlier flowering and taller plants, and for one cultivar, increased bulb respiration measured after storage. When bulbs were stored at 9 degrees C for 3 weeks, plants flowered at least 12 days earlier compared with controls stored at 27 degrees C. At 9 degrees C, as preplant bulb storage duration increased from 0 to 4 weeks, plants flowered more quickly and were taller. Within the range of 13 to 21 degrees C, 17 to 18 degrees C forcing temperatures gave the best combination of forcing time and plant quality.
Pineapple lily (Eucomis hybrids) has long, striking inflorescences that work well as a cut flower, but information is needed on proper production methods and postharvest handling protocols. The objective of this study was to determine the effects of bulb storage temperature and duration, production environment, planting density, and forcing temperatures on cut flower production of ‘Coral’, ‘Cream’, ‘Lavender’, and ‘Sparkling Burgundy’ pineapple lily. Stem length was greater in the greenhouse than the field and at the low planting density. Plants in the field at the low planting density had the shortest stem length for ‘Coral’ and ‘Cream’, but still produced marketable lengths of at least 30 cm. Planting density did not affect ‘Lavender’ and ‘Sparkling Burgundy’ stem length or number of marketable stems. The productivity (number of marketable stems per bulb) was affected only by planting density for ‘Coral’ and planting environment for ‘Cream’. Differences in stem quality and productivity differed for each cultivar and planting density over the next two seasons. The productivity of ‘Coral’ increased significantly from year to year, while the productivity of ‘Cream’ only significantly increased between the first and second years. The low planting density resulted in slightly more stems per bulb for ‘Coral’ over the next two seasons. Emergence after bulb storage treatments was highest in treatments where the bulbs were not lifted from the substrate and were subsequently grown at 18 °C. Bulbs grown in the warmest (18 °C) production temperature flowered soonest and had shorter stem lengths. For earliest flowering, bulbs should be stored in substrate in cool temperatures of at least 13 °C and forced at warm temperatures of at least 18 °C. © 2015, American Society for Horticultural Science. All rights reserved.
The impetus to compile a guide to terminology for the Easter lily was provided by a series of joint meetings between lily researchers and various industry representatives. During the course of these meetings, it became obvious that some terms did not relate the same phenomenon to all individuals. As a result, it was decided that an effort should be made to compile a list of terms directly related to Easter lily production and research. The glossary which follows is a result of those efforts. Hopefully, the guide will aid students, researchers, and industry representatives.
The effect of long-term storage of lily bulbs at -2 °C (frozen storage) and of high forcing temperatures on plant height and floral abnormalities was investigated with Oriental hybrid lilies from 1998 to 2000. `Acapulco' and `Simplon' bulbs were stored frozen at -2 °C for various lengths of time and were forced in fan- and pad-cooled greenhouses with temperatures ranging from 11 to 31 °C, depending on the season. The same cultivars were also forced in greenhouses and maintained year-round under refrigerated air conditioning with day/night temperatures of 16/15.5 °C or 18.5/18 °C. Floral development immediately after storage and at different intervals thereafter was observed by scanning electron microscopy (SEM). The prolonged frozen storage reduced the number of flowers. High greenhouse forcing temperatures during summer significantly accelerated flowering, resulted in short plants, and increased the number of abnormal flowers. Forcing at a low temperature (15.5 °C) after planting the frozen stored bulbs resulted in longer cut stems than those forced at 25 °C for 30 days after potting. Bulbs can be stored up to 9 months and still produce high-quality Oriental hybrid lilies.
Ornithogalum dubium hybrid 327 clone 2 ('327-2') bulbs were stored dry at 10°, 16°, 22°, 28°, and 35°C for six weeks after harvest. After storage, bulbs were evaluated by nuclear magnetic resonance imaging (MRI) to obtain the spin-lattice relaxation time (T1) profile across the transverse section of intact bulbs, by scanning electron microscopy (SEM) to observe inflorescence development, and by forcing in a 18.5°/18°C greenhouse to observe growth and flowering responses. Bulbs treated at 10°C had the shortest T1 (0.33 ms) through the bulb which is largely composed of scales. Leaf emergence from bulbs treated at 10°C was delayed, and plants failed to flower. This indicated that bulbs were dormant and dormancy was not broken, thus delaying initiation of floral organs. Bulbs treated at 22°C and 28°C formed the primary inflorescence with several florets. At the base of the primary scape of bulbs treated at 22°C, a vegetative apex was observed by both MRI and SEM. In the centre of bulbs where both leaves and floral organs were present, T1 was longer than that of the scales. This suggests that dormancy in the scales was broken and the leaves and scape were ready to emerge. Flowering was fastest when bulbs were treated at 22°C. The number of florets was the highest (16.0 florets) and fewest (12.6 florets) when bulbs were treated at 22°C and 35°C, respectively. Ornithogalum dubium bulbs stored at 25° and 30°C for six weeks flowered from 14 and 17 bulbs, respectively, out of 22 and flowered earlier than when stored either at lower or high temperatures. The response obtained O. dubium '327-2' hybrid was attributed to its pedigree involving O. dubium. Due to its non-destructive nature, MRI can be used to observe inflorescence development inside the bulbs during bulb storage and possibly to study the state of dormancy.
The effect of long-term storage of lily bulbs at -2 °C (frozen storage) and of high forcing temperatures on plant height and floral abnormalities was investigated with Oriental hybrid lilies from 1998 to 2000. 'Acapulco' and 'Simplon' bulbs were stored frozen at -2 °C for various lengths of time and were forced in fan- and pad-cooled greenhouses with temperatures ranging from 11 to 31 °C, depending on the season. The same cultivars were also forced in greenhouses and maintained year-round under refrigerated air conditioning with day/night temperatures of 16/15.5 °C or 18.5/18 °C. Floral development immediately after storage and at different intervals thereafter was observed by scanning electron microscopy (SEM). The prolonged frozen storage reduced the number of flowers. High greenhouse forcing temperatures during summer significantly accelerated flowering, resulted in short plants, and increased the number of abnormal flowers. Forcing at a low temperature (15.5 °C) after planting the frozen stored bulbs resulted in longer cut stems than those forced at 25 °C for 30 days after potting. Bulbs can be stored up to 9 months and still produce high-quality Oriental hybrid lilies.
The growth and flowering responses of Ornithogalum thyrsoides, ‘Chesapeake Starlight’ as influenced by bulb size and storage temperature were investigated. Development of inflorescences and florets as influenced by bulb storage temperature was studied using scanning electron microscopy (SEM). Three experiments were carried out: bulbs of 5.2 cm circumference (circum.) were treated at either 10, 16, 22, or 28 °C for a 6-week period, followed by other temperatures for a total of 18 weeks (Experiment 1); bulbs of two sizes, 8.1 and 12.8 cm in circum. received 6 weeks of 30 °C, followed by 3 and 6 weeks of 7, 10, 13, 16, 19, 22, 25 and 30 °C (Experiment 2); bulbs of two sizes, 5.7 and 6.5 cm in circum. were dried at 20 °C for a week and were potted after storing for 6 weeks at 30 °C (30 °C/6W) followed by either storage at 20 °C for 4 or 8 weeks (20 °C/4W or 20 °C/8W) and finally at 10 °C/4W or 20 °C/8W (Experiment 3). Development of inflorescences and florets were studied using SEM (Experiment 1). Bulb sizes of ‘Chesapeake Starlight’ (Experiments 2 and 3) did not affect flowering. The shoot apex of the bulb is vegetative at harvest and bulbs should be stored dry at 28–30 °C for 6 weeks for rapid inflorescence development. When root primordia were clearly visible at the end of the 20 °C treatment, the scape of the first inflorescence is clearly formed, and bulbs are then treated at 10 °C. When bulbs were treated at 28 °C during the first 6 weeks (week 0–6), flowering accelerated. Flowering was also accelerated and only one inflorescence was produced from the center when bulbs were stored at 10 °C/6W during the second and third 6 weeks (weeks 7–12 and weeks 13–18). A sequential treatment of 30 °C/6W–10 °C/6W–10 °C/6W ensured a longer flower stem and accelerated flowering of the first inflorescence, and this was verified by SEM. Flower stem length increased significantly and only one inflorescence was produced from the center when bulbs received 30 °C/6W–20 °C/4W–10 °C/8W as compared to bulbs that received 30 °C/6W–20 °C/4W–10 °C/4W. To produce two or more inflorescences per bulb, we recommend treating bulbs at 10 °C/3–4W or 13 °C/3W. Descriptions of the development of the first and second inflorescence and of a single flower using SEM will be useful to document the development of inflorescence and flowers during bulb storage and to further develop precise treatment temperatures and durations to shorten the pre-treatment period of bulbs after harvest.
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