Progress 10/01/03 to 09/30/06
Outputs
Several hundred cross pollinations between Dracaena and Cordyline flowers made in attempt to create an intergeneric hybrid have resulted in 12 seeds which are still under observation. Several hundred cross pollinations between different Dracaena species were also made in attempt to make an interspecific hybrid. About 25 seeds have resulted from these crosses and it seems that one is possibly an interspecific hybrid (D. xmasseffiana x D. fragrans). Flower induction experiments using GA3 and cold temperature treatments have had limited success. GA3 and cold temperature treatments were successful in inducing D.xmasseffiana to flower more frequently at higher concentrations. However, in the other species and varieties tested, no additional flowering occurred due to the treatments. Pollen germination using Brewbaker and Kwack's medium were conducted on several species. Freshly opened anthers were teased open in a drop of media on a slide and placed in a covered Petri dish
containing moistened filter paper. The Petri dish was placed under lights overnight and the next day at least 300 pollen cells were counted and germination determined. The germination percentages for D. fragrans 'Massangeana', D. surculosa, D. deremensis 'Santa Rosa' and 'Warneckei', D.xmasseffiana, and D.xmasseffiana MREC 98-12 were 22.63, 10.6, 3.95, 33.4, 8.4 and 24.3%, respectively. This information will help with any further cross pollination efforts. The mutant form of D.xmasseffiana (D.xmasseffiana MREC 98-12) was confirmed as a tetraploid with chromosome counts showing it has 78 chromosomes and the diploid form has 39. Dracaena deremensis 'Lisa' in vitro cultures were initiated and callus tissue induced on the bases of stem explants. Callus were treated with 2 concentrations(0.005% and 0.01%) and 2 durations(24 and 48 hours) of oryzalin for a total of 4 treatments. Oryzalin has chromosome doubling capabilities. Calli were placed on shoot regeneration media and new plantlets
were formed. To test for polyploidization, flow cytometry was conducted on leaf tissues and one plant was found to be a tetraploid. This plant has some morphological differences from untreated diploid plants, including smaller leaves and shorter internode length. The plant will be observed for suitability as a new cultivar. Newly forming axillary buds of Dracaena deremensis 'Santa Rosa' field plants were treated with oryzalin at 2 concentrations(0.005% and 0.01%) and 2 durations(24 and 48 hours) for a total of 4 treatment to attempt to created a tetraploid. After buds grew to size, they were tested for polyploidization using flow cytometry and one mixoploid was found. Four varieties of unrooted Dracaena cuttings were irradiated with Cesium 137 gamma rays and the LD50 dosage was determined. The LD50 dosages for D. deremensis 'Santa Rosa', D. fragrans 'Massangeana' and 'Victoriae', and D.xmasseffiana were found to be 18.07, 13.58, 20.87, and 23.29 Gy, respectively. Percent mutation
ranged from 0% to 55% with the most common type being chlorophyll mutations such as all yellow or all green leaves. Large numbers of cuttings can now be irradiated in the LD50 range to induce more mutations.
Impacts
Dracaena is a highly important nursery product in Hawaii, ranking 2nd among all floriculture and nursery products in 2005. New cultivars to introduce to the market would help the Hawaii foliage industry cater to consumer's ever changing preferences and keep sales up. This project used mutation induction to create plants with different morphology and different variegation. If these plants are suitable to introduce to the market, they could help Hawaii's growers by giving them unique products no one else has and putting them on the cutting edge of the foliage market.
Publications
- No publications reported this period
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Progress 10/01/04 to 09/30/05
Outputs
Several hundred pollinations between different Dracaena have been attempted. Only 2 fruit have been obtained which are a result of a cross between D. angustifolia 'Honoriae' x D.xmasseffiana MREC 98-12. These two seeds have not yet germinated. Dracaena flower only once a year and this is a major limiting factor in hybridization, so an efficient method of out of season flower induction is desired. Additional flower induction experiments have been attempted using cold temperature treatments since the last report. First, plants were placed in cold temperature chambers for 7 nights (5 PM till 8 AM). D. deremensis 'Janet Craig', D. fragrans 'Massangeana', D. fragrans 'Santa Rosa', and D.xmasseffiana were treated at temperatures of 6, 9, 12, and 15 degrees Celsius. This experiment attempted to simulate natural conditions in which temperatures are warmer during the day and cooler at night and thought would be a more effective method to induce flowering. However, none of the
plants had any flowering response. A second experiment is in progress. Plants are being subjected to 20 and 40 days in the cold temperature chambers. D. fragrans 'Massangeana', D.xmasseffiana, D. surculosa, D. fragrans 'Massangeana Compacta' and D. 'Fantasy' are being treated at 12 and 15 degrees Celsius. Chromosome counts have been conducted on several species and cultivars of Dracaena to confirm their ploidy levels. The numbers were found to be D.xmasseffiana (39), its mutant form D.xmasseffiana MREC 98-12 (78), and their parents D. surculosa (40) and D. fragrans 'Massangeana' (38). This confirms our earlier speculations that the mutant form D. xmasseffiana MREC 98-12 is a tetraploid form of D. xmasseffiana. A good medium for the induction of callus in Dracaena has been tested and found to be suitable. A medium for regeneration of shoots is currently being tested. When suitable media formulations are determined, the callus will be treated with oryzalin to induce polyploidy. Induced
mutations using irradiation treatments is in progress. 5 inch long unrooted cuttings were irradiated with x-rays with dosages ranging from 0 to 150 Gy. D. fragrans 'Santa Rosa', D. deremensis 'Warneckei', D. deremensis 'Janet Craig', D. fragrans 'Massangeana', D. concinna, D. fragrans 'Victoria', and D. xmasseffiana were treated in this experiment. Observations to date have shown that cuttings exposed to increasing dosages have decreased rooting and shoot development. Also, several different color and variegation mutations have occurred, including conversion to all green leaves, all white (albino) leaves, and different variegation patterns. Seeds of D. concinna and D. fragrans 'Massangeana' have also been irradiated with X-rays ranging in dosage from 0 to 200 Gy. These seeds have yet to germinate. Permission has been obtained to use an irradiator which exposes the plants to gamma ray irradiation. This is generally a more efficient method of mutation. A similar experiment to that of
the X-ray irradiation is planned, with unrooted cuttings 5 inches in length as the material. Cuttings will be exposed to 0 to 500 Gy dosages and then rooted. Observations will be made on root and shoot development.
Impacts
Dracaena were ranked 2nd in sales among all foliage and 3rd among all floriculture and nursery products in Hawaii in 2004. Despite this economic importance, however, new varieties are not being created and introduced into the market. With ever changing consumer preferences, the Hawaii Nursery industry must also change to keep their sales up. This project aims to create new Dracaena cultivars for the Hawaii foliage industry through a variety of methods. Characteristics such as new colors, new and unique variegation, and new and unique morphology are desired. Traditional breeding through cross pollination, induction of polyploidy using in vivo and in vitro methods, and induced mutations through irradiation, both x-ray and gamma ray, are being employed to attempt to create these new characteristics.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
A field plot at the University of Hawaii (UH) Experimental Station in Waimanalo, Oahu containing four commercial varieties of dracaena plus a large number of potted dracaena has been established. Materials are also available through the Lyon Arboretum (LA), California & Hawaii Nursery (C&H), a commercial planting in Waimanalo, Oahu, the Magoon facility at the University of Hawaii, the Maui Agricultural Research Center (MARC), and the Waiakea Research Station (HWRS). Pollinations of Dracaena x Cordyline have been made at Magoon, LA, C&H, HWRS, and MARC. Most did not result in fruits except for 4 fruits formed at HWRS which are being evaluated. One Dracaena hybrid (D. xmasseffiana x D. fragrans) growing at Magoon is about 20 cm tall and appears to have the characteristic spotting of D. surculosa and leaf morphology characteristics similar to D. fragrans. To induce flowering, GA3 solutions of 500 to 6000 mg/L were applied to D. fragrans (Massangeana and Massangeana
Compacta), D. deremensis (Janet Craig, Janet Craig Compacta, Santa Rosa, Warneckei, and Bausei), and D. xmasseffiana. Also, D. deremensis (Santa Rosa and Janet Craig), D. fragrans Massangeana, and D. xmasseffiana were cooled for 0-9 days at 8-12 C. D. xmasseffiana treated with 500, 1000, and 2000 mg/L of GA3 responded with flowering rates of 41.67%, 58.33% and 62.5%, respectively, while untreated plants did not flower. D. fragrans Massangeana flowered at insignificant rates. D.xmasseffiana chilled for 3, 6, or 9 days at 12 C flowered after three weeks at the rate of 16.9%, 39.2%, and 86.7%, respectively, while control plants did not flower. All treatments were unsuccessful at initiating flower development in the other plants, and alternate methods will be tested. The average area of D. xmasseffiana MREC 98-12 stomatal guard cells was 68% larger than the average area of D. xmasseffiana stomatal guard cells, indicating that D. xmasseffiana MREC 98-12 is most likely a polyploidy.
Chromosome counts will be done to confirm this speculation. Tissue cultures of several commercial varieties have been initiated. Media for the initiation of cultures, induction of adventitious buds, shoot elongation, and rooting are being tested. The plants will then be treated with colchicine and tested for mutation. Aniline blue was used to stain pollen of D. xmasseffiana, D. deremensis Janet Craig, D. surculosa, and D. xmasseffiania MREC 98-12. Pollen grains that do not take up the stain are not viable while those that do show the presence of cytoplasm and the possibility of fertility. The percentage of pollen grains stained in the different varieties was highly variable, ranging from 28.9% to 71.2%. Storage of D. xmasseffiana and D. deremensis Janet Craig pollen was attempted at -5 C. Pollen was removed at weekly intervals and stained with aniline blue to determine remaining viability. However, the average percentage of pollen grains taking up the stain increased after storage,
implying that this method of viability testing is not highly accurate. A more accurate test of viability will need to be used in future pollen storage studies.
Impacts
Dracaenas are popular foliage plants, yet no systematic breeding program exists to create new varieties for the nursery industry. Consumer preferences are constantly changing and the nursery industry must continuously offer new products to keep up with ever changing demands. The overall objective of the project is to develop new, improved, and more colorful Dracaena cultivars through hybridization and through selection of chimeras in tissue culture for the Hawaii Nursery industry.
Publications
- No publications reported this period
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Progress 10/01/02 to 09/30/03
Outputs
No progress to report. This project was initiated on October 1, 2003.
Impacts
No impact to report. This project was initiated on October 1, 2003.
Publications
- No publications reported this period
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