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- Author or Editor: A.A. De Hertogh x
Abstract
Dutch-grown tuberous-rooted dahlias, ‘Kolchelsee’ and ‘Park Princess’, were forced from January to June in 1975 and 1976. In all experiments, plant height was controlled by applying 0.5 mg/pot of ancymidol 2 weeks after planting.
Fertilization was essential and an application of one of several slow-release formulations of Osmocote or weekly applications of 20N—8.8P—16.6K (200 ppm N) as a soluble fertilizer produced high quality plants which flowered in approximately 70 days. The highest quality plants and best height control was obtained with 25°C day and 16° night temperatures. Flowering was delayed at 24/12° day/night temperatures, and although flowering was accelerated at 28/17° and 29/20° day/night temperatures plant quality was adversely affected.
Natural spring photoperiods which increased from 10 to 14 hours were optimal for forcing. Long days given either as a 16-hour photoperiod or as a 4-hour night break delayed flowering slightly. Dahlias grown under an 8-hour photoperiod flowered the earliest but not all plants flowered. Dahlias required high light intensities during forcing. Under 50% shading plants were too tall for pot plant use even after treatment with ancymidol.
Abstract
Cell-free extracts which incorporated mevalonate-2-14C (MVA) into terpenes were obtained from shoot tissue of Tulipa gesneriana L. cv. Golden Melody. Maximal incorporation occurred at pH 6.5 in 0.1 M KH2 PO4-K2HPO4 buffer with an incubation temperature of 35°C. Total incorporation was linear up to 5 mg protein/assay and it could be enhanced by increasing MVA concentration up to 8 × 10-8 M. After differential centrifugation, all enzymatic activity was located in the 100,000 × g supernatant. In combination Mg++ and Mn++, ATP stimulated incorporation more than CTP, GTP, and UTP. Using ATP as the energy source, Mn++ was highly stimulatory at 1 and 5 × 10-3 M. Mg++ alone or in combination with Mn++ was less effective than Mn++.
The radioactivity from MVA was recovered in 2 fractions: the “neutral” fraction isolated by extraction with benzene, and the “acid hydrolyzable” fraction extracted with benzene after acid hydrolysis of the residual aqueous “neutral” fraction. For subsequent identification of the neutral terpene products, the optimal conditions are either high protein concentration (18 mg/assay) after a 15,000 × g centrifugation and a 4-hr incubation period or high protein concentration without centrifugation and a 1-hr incubation period. The optimal conditions for identification of the acid hydrolyzable products are low protein concentration (5 mg/assay) and 1-hr incubation.
Abstract
Potted ‘Ace’ lily bulbs were treated with 1000 ppm of either gibberellin A3 (GA3) or gibberellins A4+7(GA4+7) as a soil drench using 200 ml per pot on January 6, 1971. GA treatments had no effect on the time of floral initiation, however, GA3 decreased the days to flowering when compared to either GA4+7 or water controls. GA4+7 and GA3 reduced the number of primary flowers initiated. and completely inhibited the initiation of secondary flowers. GA4+7 increased the number of primary flowers which aborted shortly after initiation and GA3 did not. Both GAs increased plant height; GA4+7 had the greater effect. GA4+7 significantly reduced the length of the lower leaves, but none of the treatments affected the number of leaves produced.
Abstract
Nonprecooled and precooled ‘Ace’ lily bulbs were placed in the dark at 5, 9, 13, 17, and 21 °C and basal root growth determined at weekly intervals for 5 weeks. Roots originating from the basal plate were designated as primary roots; those originating from the primary roots were designated as secondary roots. The total fresh wt of secondary roots of nonprecooled and precooled bulbs increased with length of storage and increased temp. Optimum root growth occurred at 21°C. Primary roots of nonprecooled bulbs responded similarly to the secondary roots, while those of precooled bulbs had a temp optimum of 17 to 21°C. It was concluded that for commercial use, both nonprecooled and precooled bulbs should be initially grown at approx 17°C to stimulate basal root growth.
Abstract
Using a standard forcing program for early February flowering, the histogenesis of the tulip apical meristem from the vegetative state to the differentiated, immature flower was observed with the scanning and light microscopes. Root and central bulblet development were observed only with the light microscope. Total scape and root growth were measured from initiation to anthesis. The apex was vegetative on July 21, prefloral on August 1, and reached the reproductive stage “G” on August 15. The first internode was formed by August 7 and the last internode was formed just prior to reaching stage “G”. Cell division was observed in the scape from formation until after planting at 9°C. A second phase occurred in the epidermal cells, nodal regions, and vascular bundles immediately after the plants were placed in the greenhouse. It preceded the rapid rate of cell elongation in the scape. Root initiation had commenced by late July. Root growth and differentiation continued in the basal plate until mid-September, resumed during the cold treatment, and continued after the plants were placed in the green-house. The central bulblet was initiated by early August and continued to develop throughout the forcing program.
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.
Shoot apical meristems of Freesia ×hybrida Klatt `Rossini' reached the reproductive state after 3 weeks of precooling at 9C. Meristems isolated after 6 and 7 weeks of precooling showed the development of the initial four florets of the inflorescence.
In recent years, several physiological disorders of unknown origin have been observed on Oxalis regnellii and O. triangularis, two widely forced species. Therefore, an experiment was carried out in the NCSU Phytotron. The forcing temperatures were 18/14C, 22/18C, and 26/22C (day/night), and these temperatures were combined with 9-h and long day (3-h night break) photoperiods. In addition, two planting media (Metro 360 and Sunshine no. 4) were used. Control plants were grown under greenhouse conditions. With O. regnellii, leaf chlorosis and wrinkling were prevalent in the greenhouse. In the phytotron, the highest quality plants with the least amount of leaf disorders were produced under LD at 26/22C. No differences were obtained with the planting media. With O. triangularis, the highest quality plants with the least leaf disorders (bronzing and wrinkling) were grown in the phytotron at 26/22C. In addition, LD significantly enhanced flowering. Leaf disorders were prevalent in the greenhouse and enhanced with Sunshine no. 4.
Abstract
It has been demonstrated that flower induction and differentiation in the tulip occurs long before flowering takes place in the spring (1, 2). In the Northern Hemisphere, the initiation of floral primordia begins soon after the bulbs are harvested from the fields in late June or early July and normally, differentiation of the floral parts is completed by late August or early September. By determining the effect of various post-harvest storage temperatures on the development of the floral parts, Luyten et al. (2) showed that the optimal temperature range for flower initiation and development is 17 to 20°C. During the course of these studies, it was observed that the apical meristem passed through seven well-defined phases of development. They were designated by use of the Roman numerals I through VII. Later, Beyer (3) reclassified these stages using alphabetical letters and subscripts selected to correspond to the morphological stages of development e.g. “P1” to indicate the first outer whorl of perianth. Beyer’s “G” stage is comparable to Blaauw’s stage VII (Figure 1). The two designations have been used interchangeably in the literature.
Dutch-grown `Deutschland', `Fanal', and `Rheinland' Astilbe, harvested 1 Nov. 1992 and shipped to the United States, were dissected to determine the stage of floral development after 0, 2, 4, 6, 8, 10, 12, or 15 weeks of 2C storage. Astilbe crowns were also planted after 15 weeks of 2C storage and floral development was determined after 1, 2, or 3 weeks of greenhouse forcing. On arrival, multiflower inflorescences were clearly visible. A pattern of abortion and reinitiation occurred during 2C storage. Floral development was markedly repressed when ecodormancy was imposed, but development resumed during greenhouse forcing. During the observational period, floral organ numbers were variable, and morphological abnormalities were observed. In a second experiment, physiological maturity of the crowns was evaluated by harvesting crowns of `Bumalda', `Europa', `Federsee', and `Rheinland' on 15 Sept., 1 Oct., 15 Oct., 1 Nov., and 15 Nov. in The Netherlands. Optimal harvest period was from 1 Oct. to 1 Nov., depending on the cultivar. Crowns harvested before this period were physiologically immature. Crowns harvested during the 4-week window produced the highest overall plant quality and performed as physiologically mature crowns. Astilbe crowns harvested after the 4-week window produced plants with lower forcing qualities and were determined to be beyond the optimal physiological state for forcing.