August A. De Hertogh
August A. De Hertogh
A. A. De Hertogh and M. Tilley
Almost all Amaryllis (Hippeastrum) forced in the U.S. and Canada by either homeowners or commercial forcers are grown overseas. In order to comply with USDA/APHIS plant quarantine regulations, all bulbs must be free of soil. Thus, they are washed once or twice prior to packing and shipping. As a result of this treatment, the bulbs arrive with only basal roots and no secondary roots. Therefore, over the past year, 2 hand made mixes and 7 commercially prepared mixes were evaluated using 2 cultivars each of Swaziland- and Dutch-grown bulbs. The effects of these media on forcing characteristics, e.g. total plant height, leaf length, flower number, etc. were examined. Also, the influence of the various media on basal root growth and formation of new secondary roots was measured. The results of these 2 studies will be presented.
A.A. De Hertogh and M. Tilley
The Swaziland-grown Hippeastrum bulbs `Summertime' and `Sun Dance' reached the market and flowering stages of development in fewer days than the Dutch-grown bulbs `Apple Blossom' and `Red Lion'. `Sun Dance' was the quickest flower and `Red Lion' the slowest. The effects of the planting medium on days to market and flowering were variable and no medium appeared to be the best for this criterion. `Summertime' and `Red Lion' produced longer leaves at flowering than `Apple Blossom' and `Sun Dance'. Three media that led to the production of the longest leaves, a desirable trait, were: Sunshine no. 4, Fafard 3-B, and Sunshine Post-Harvest. `Apple Blossom' was the tallest cultivar followed by `Sun Dance', `Red Lion', and `Summertime'. Effects of the planting medium on total plant height were variable. The overall plant quality ratings for use as potted plants ranged from 3.4 to 3.8 out of 4 for `Summertime', `Sun Dance', and `Red Lion'. `Apple Blossom' was rated 3.0 because it was tall and had short leaves. It would be suitable as a cut flower. Regardless of the planting medium used, `Apple Blossom' lost the greatest amount of old basal roots. Consequently, it produced many new basal roots. The planting medium had variable effects on old and new basal roots and secondary root growth, depending on the cultivar. Based on all the flowering criteria and the rooting responses, the best media for all cultivars as potted plants were Fafard 3-B and Sunshine Mix no. 4. Fafard no. 2 was best for cut-flower usage since it produced taller plants with a good root system.
Gwendolyn H. Pemberton and A.A. De Hertogh
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.
A.A. De Hertogh and L.B. Gallitano
Dutch-grown Hippeastrum bulbs (`Apple Blossom' and `Red Lion') were packed in five readily available and economical packing systems and after transport and storage were evaluated as flowering potted plants. After being harvested and graded, bulbs were specially packed and placed in perforated cardboard boxes, shipped by boat to Raleigh, N.C., and stored in the original packing materials for 84 days at 48 °F (9 °C). At planting time, the best old basal root system and lowest disease incidence for both cultivars was obtained when bulbs were packed with hout-wol, a type of excelsior, in perforated polyethylene bags and placed in perforated cardboard boxes. Plants from bulbs with this system and those packed loose in polyethylene bags flowered the earliest. At full flower, the longest leaves were obtained with the hout-wol, box only, and wood chip systems. There were no significant effects of the five packing systems on floral stalk length, number of flowers produced per stalk, flower diameter, strength of the first floral stalk or leaves, or overall plant quality. After flowering, the root systems were harvested. The hout-wol packing system significantly increased the fresh weights of the old basal roots retained, secondary roots produced, and total weights of the root system. there were significant differences between cultivars. `Apple Blossom' produced fewer roots and lower quality plants (shorter leaves and taller floral stalks) than `Red Lion'. Other significant cultivar differences, e.g., days to flower, were attributed to genetic variation. Based on the most desirable forcing characteristics, the superior packing system for shipping and storing Dutch-grown Hippeastrum bulbus was hout-wol combined with perforated polyethylene bags.
Ludwika Kawa and August A. De Hertogh
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.
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.
A.A. De Hertogh, L. Gallitano, and K. Kim
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.
Seung-Hyun Kim, A.A. De Hertogh, and P.V. Nelson
Two experiments were conducted to determine the effects of applied ancymidol, chlormequat, daminozide, paclobutrazol, and uniconazole on early spring (March) and late (May) spring forcing of Dutch-grown Bleeding Heart [Dicentra spectabilis (L.) Lem.] as a flowering pot plant. Most of the plant growth regulator (PGR) treatments delayed flowering, however, the average time to flower after planting was from 17 to 21 days for untreated plants and delays were only 3 to 6 days with PGR treatments. Thus, the effect is not important commercially. Acceptable plant quality and height control not only at flowering but also 14 days later was obtained with two sprays of 3000 mg·L-1 (ppm) daminozide or two sprays of 50 mg·L-1 paclobutrazol. Uniconazole reduced total plant height, however, because the inflorescence did not elongate, plant quality was greatly reduced. Most ancymidol sprays were phytotoxic producing a chlorosis of the leaf margins. Media drenches of ancymidol or chlormequat did not control total plant height. Sprays and media drenches of ancymidol, daminozide, paclobutrazol, and uniconazole produced plants with a very deep green leaf color, but chlormequat did not. The total number of shoots per tuberous root, the number of shoots with flowers, and stem strength were not significantly affected by PGR treatments. If the tuberous roots have been properly cold treated, they initiate growth rapidly after planting. Thus, the first PGR spray must be applied immediately after shoot growth is initiated, which was 6 to 8 days after planting, followed by a second spray 5 days later. Two applications are necessary because of uneven shoot emergence and growth from the tuberous roots.