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- Author or Editor: Teresa A. Cerny x
Seed of five species of petunia and 10 cultivars of Petunia xhybrida were obtained from several sources and plants were fingerprinted using DNA amplification fingerprinting (DAF). Within some species, variable fingerprints were generated between individual plants from the same seed source and/or different sources. Consistencies were found among DAF profiles by bulking the leaf tissue from 10 different plants, but not five plants. Each of 10 octamer primers used during the study revealed polymorphic loci between the species and cultivars. Among the 201 bands produced, 146 (73%) loci were polymorphic and these could be used to distinguish between each of the species and cultivars. Scoring for presence and absence of the amplified bands was used to generate a phylogenetic tree and to calculate the pairwise distances between each of the taxa using parsimony (PAUP) analysis. The tree generated using DAF molecular markers separated P. axillaris from P. parodii (two white-flowered species), and distinguished between the violet-flowered species, P, inflata, P. integrifolia, and P. violacea.
Earlier research suggests that P. axillaris, P. inflata, P. parodii, and P. violaceae may be part of the evolution of P. × hybrida. The precise probe and endonuclease combinations which would distinguish between these closely related species has not been found using other methods of DNA fingerprinting. Knowledge of the relationships among species within this genus could serve to advance breeding of P. × hybrida. The objectives of this project were to use DNA amplification fingerprinting (DAF) to fingerprint P. × hybrida and the four previously discussed species to show differences between them and to demonstrate the utility of DAF for floricultural crops. DAF does not require a precise probe; instead, it uses short arbitrary primers. Petunia seeds were obtained from foreign sources. Seedlings were grown in 0.4-liter plastic pots containing soilless medium under glass greenhouse conditions of 24/18°C. Tissue samples were collected, frozen with liquid nitrogen and stored in an ultra-low freezer. DNA was isolated and then amplified. Six different primers were used throughout the research. By using different primers, different segments of the DNA were amplified so more information about the relationships between species could be gained. Gels were both visually examined and quantitatively analyzed by a densitometer. Primer sequences GA-AAC-GCC and GT-TAC-GCC were found to be the most effective in showing amplification fragment length polymorphisms. Distinct differences were found between each of the species.
Our overall objective was to use DNA Amplification Fingerprinting (DAF) to determine the relationships between Petunia × hybrida and four wild petunia species,P. axillaris, P. inflata, P. parodii, and P. violacea. This research was to optimize the DAF amplification reaction for petunias, check for variability in the fingerprints among different seedlings of the same species and screen primers to be used for Identifying polymorphisms between cultivars of P. × hybrida end the four wild species. Optimization of the DAF procedure was accomplished by varying concentrations of DNA template (O - 10 ng), MgCl2(0 - 10 mM), and primers (0 - 30 μM). Optimum concentrations were found to be 1.0 ng DNA template and 2.0 mM MgCl2. Clearly resolved banding patterns were produced using primer concentrations from 3.0 μM to 30 μM. When separate seedlings of each wild species from the same seed source were fingerprinted, profiles were consistent. Seeds from other sources are presently being collected to investigate variation between sources. Twenty-five heptamer and octomer primers varying in GC content were screened and ten produced clear banding patterns for the Petunia species. These primers have produced polymorphic profiles between the pink-flowering species and the white-flowering species. Several primers have shown distinct polymorphisms between P. axillaris and P. parodii, the two white-flowering species, which have very similar morphological traits. Similarities in the banding patterns have been found between P. × hybrida and these wild species.
Growth chambers constructed from photoselective plastic films were used to investigate the effects of light quality on height manipulation and flowering of photoperiodic plant species. Three types of treatment films were used; control, a far-red light intercepting film (YXE-10) and a red light intercepting film (SXE-4). The red (600-700 nm):far-red (700-800 nm) ratios and phytochrome photoequilibrium estimates for the control, YXE-10 and SXE-4 films were 1.0 and 0.71, 1.5 and 0.77, and 0.71 and 0.67, respectively. The photosynthetic photon flux was adjusted to uniformity among chambers using neutral density filters. Spectral filters did not effect minimum and maximum air temperatures. Experiments were conducted using quantitative long day (Antirrhinum majus and Petunia × hybrida), quantitative short day (Zinnia elegans and Dendranthema × grandiflorum) and day-neutral (Rosa × hydrida) plant species under natural short-day conditions. Plants produced under the YXE-10 filters were significantly shorter than the control plants, while plants produced under the SXE-4 films had similar or increased height compared to the control plants. However, both height response and flowering times varied with the crop species. Flowering time of Rosa × hybrida plants was uniform among all treatments. Flowering of quantitative long-day plants was delayed by at least 10 days under the YXE-10 film and was most responsive to the filtered light. Flowering of quantitative short-day plants was delayed by 2 days under the YXE-10. Days to flower for plants produced under the SXE-4 film were similar to the control plants for all species tested.
A research collaboration between Clemson Univ. and Mitsui Chemicals, Japan, has been established to develop and test photoselective greenhouse covers that can filter out far-red (FR) light and control plant height with minimal use of chemicals. The effects of polymethyl methacylate (PMMA) filters containing FR-intercepting dyes were evaluated on watermelon, pepper, chrysanthemum, and tomato to select an optimum dye concentration. As the dye concentration increased, FR interception increased, photosynthetic photon flux (PPF) decreased, and phytochrome photoequilibrium increased from 0.72 to 0.82. Light transmitted through photoselective filters reduced plant height effectively in all species tested. However, watermelon was the most responsive (50% height reduction) and chrysanthemum was the least responsive (20% height reduction) to filtered light. Tomato and peppers had an intermediate response. In watermelons, total shoot dry weight was reduced over 25% compared to the control plants, with a progressive decrease in shoot weight as the dye concentration increased. The specific stem dry weight was gradually reduced as the dye concentration increased. Specific leaf dry weight was slightly reduced under filters, suggesting that smaller plants as opposed to a reduction in dry matter production primarily caused total dry weight reduction. Light transmitted through filters reduced percentage dry matter accumulation into stems from 27% to 18% and increased dry matter accumulation into leaves from 73% to 82%. Photoselective filters are effective in controlling height similarly to chemical growth regulators. Considering the PAR reduction by increase in dye concentration, a dye concentration that gives a light reduction of 25% or 35% may be optimum for commercial development of photoselective films.
The productivity and profitability of annual and perennial field-grown specialty cut-flower species were evaluated for the southeastern United States. Data were collected on 20 annuals and 20 perennials in 1992 and on 19 annuals and 19 perennials (10 in their second year of production) in 1993. Productivity and profitability were based on yield and stem length measurements. Yield was expressed as total number of stems harvested. Income per 30-cm center was predicted from the number of stems ≥41 cm long that were harvested. Some species had high yields but stem lengths were too short for most market outlets. Among those species that combined high yield with long stems and resulted in high profitability without major pest or postharvest problems were the perennials Achillea filipendulina Lam., Echinacea purpurea (L.) Moench, Liatris spicata (L.) Willd., and Platycodon grandiflorus Jacq. A. DC. and the annuals Antirrhinum majus L., Cosmos bipinnatus Cav., Scabiosa atropurpurea L., and Zinnia elegans Jacq. Low overhead of field production coupled with productive species could prove to be profitable.
Height control and flowering responses to uniconazole spray or drench treatments were measured for `Multibloom Scarlet' and `Red Elite' geranium (Pelargonium ×hortorum L.H. Bailey). Total plant height of both cultivars was reduced proportionately to the height of a 10-cm container when the uniconazole drench concentration was 0.025 mg a.i./pot. Used as a spray, uniconazole was not as effective in restricting total plant height of either cultivar. Foliage height was shortened more than inflorescence height. Inflorescence diameter was decreased with increasing uniconazole drench concentrations. Sprays did not affect inflorescence diameter of either cultivar. Uniconazole effect on days to flower varied with cultivar and application method. Chemical name used: (E)-(S)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-pent-1-ene-3-ol (uniconazole).
The objective was to determine the productivity and profitability of field-grown specialty cut flowers. Productivity and profitability of cut flowers were based on yield and stem length measurements. Two 54 m2 beds were planted with 20 annual cut flower species and two beds with 20 perennial species. The experiment was a randomized complete block design with 16 plants per species in each block. Total number of flower stems per replication produced by annual species ranged from 35 to 1946. Percentage of productive plants was 100% for most of the annual species. The total number of flower stems harvested per productive plant ranged from 4 to 122 and bunches of flowers per 0.09 m2 varied from less than 1 to 12. Income estimates per 0.09 m2 indicated some species were highly profitable. Total number of flower stems per replication produced by perennial species ranged from 8 to 1501. Seven species of perennials did not bloom. The 3 perennial species with the greatest total number of flower stems harvested had 100% of the plants in production during the growing season and a greater total number of flower stems harvested per productive plant. Only four perennial species showed a positive income estimate per 0.09 m2. Percent mortality had an effect on productivity and was greater overall for the perennial species than the annual species. The lower overhead associated with field production coupled with highly productive species proved to be profitable.
New cultivars of seedling geraniums are bred for compact growth habit to be grown in plugs, cell packs, or 0.4-liter pots. Chlormequat chloride (CCC) is recommended for use on these cultivars grown in 0.4-liter pots to increase the branching and green color of leaves. The objective was to determine concentration of uniconazole (UNI) foliar spray and medium drench and to compare the efficacy of UNI with CCC at 750 mg·liter-1 on Pelargonium × hortorum cvs. Red Elite (RE) and Multibloom Scarlet (MS). Growth retardants were applied 5 weeks after sowing when plants had five leaves 2.5 cm in diameter. Three plant size variables (height, width, and peduncle length) and 3 flowering variables (flower diameter, days to flower, and bud number) were measured. The experiment showed that CCC reduced all size variables in RE and MS compared to the controls. UNI drenches at applications of 0.05 and 0.025 mg a.i./pot controlled size variables similar to CCC drenches in RE. In MS, all UNI drenches decreased plant size variables more than CCC with one exception. UNI sprays did not reduce size like CCC sprays on RE. UNI spray controlled size variables of MS similar to CCC when administered at 20 mg·liter-1. CCC reduced flower diameter more than UNI in both cultivars. In MS, UNI drench reduced days to flower compared to CCC. Both growth regulators increased bud number of MS compared to the control.
Growth chambers constructed of photoselective plastic films were used to investigate light quality effects on flowering and stem elongation of six flowering plant species under strongly inductive and weakly inductive photoperiods. Three films were used: a clear control film, a far red (FR) light absorbing (AFR) film and a red (R) light absorbing (AR) film. The AFR and AR films intercepted FR (700 to 800 nm) and R (600 to 700 nm) wavelengths with maximum interception at 730 and 690 nm, respectively. The phytochrome photoequilibrium estimates of transmitted light for the control, AFR, and AR films were 0.71, 0.77, and 0.67. The broad band R:FR ratios were 1.05, 1.51, and 0.77, respectively. The photosynthetic photon flux was adjusted with neutral density filters to provide similar light transmission among chambers. Zinnia elegans Jacq., Dendranthema×grandiflorum Kitam. (chrysanthemum), Cosmos bipinnatus Cav., and Petunia×hybrida Vilm.-Andr. plants grown under the AFR film were shorter than control plants. The AFR film had no effect on height of Antirrhinum majus L. (snapdragon) or Rosa×hybrida (miniature rose). Anthesis of zinnia, chrysanthemum, cosmos (short-day plants), and miniature rose (day-neutral plant) was not influenced by the AFR films. Anthesis of petunia and snapdragon (long-day plants) was delayed up to 13 days by AFR films under weakly inductive photoperiods. In petunia, initiation and development of floral structures were not affected by the AFR films during strongly inductive photoperiods. However, during weakly inductive photoperiods, initiation of the floral primordia was significantly delayed and overall development of the floral meristem was slower than control plants indicating that the AFR films could increase the production time if long-day plants were produced off-season. Daylength extension with electric light sources could overcome this delay in anthesis yet achieve the benefit of AFR films for height reduction without the use of chemical growth regulators.