Plug flats of Begonia × semperflorens-cultorum Hort. `Pizzazz Red', Vodka', and `Viva' were provided 0, 50, 125, or 200 μmol·s-1·m-2 metal-halide supplemental irradiance in the greenhouse for 0, 2, 4, 6, or 8 weeks. Treatments were initiated when seedlings were in the first true leaf stage (2 weeks after sowing). Plug-grown begonias reached transplantable dry weight and leaf area after 4 weeks of 125 μmol·s-1·m-2 supplemental exposure, while those under O and 50 μmol·s-1·m-2 required 6 to 8 weeks. Fewest number of days to visible bud and anthesis and the fewest number of nodes for all cultivars occurred after 2 weeks of 125 μmol·s-1·m-2 supplemental exposure. The same conditions achieved the greatest final leaf area and plant height; however, final dry weight was unaffected. Additional supplemental irradiance and/or exposure time did not accelerate flowering or improve vegetative growth of finished plants.
Two studies were conducted to determine the influence of decapitation (pinch treatment) and photoperiod treatments on stem length, days from planting to harvest, and flowering stem yield in two delphinium cultivars. Plants of Delphinium ×belladonna Hort. ex Bergmans `Völkerfrieden' received a hard pinch (removal of apex and all stem and leaf tissue associated with leaves ≤10 cm), soft pinch (removal of apex and all stem and leaf tissue associated with leaves ≤4 cm), or no pinch. Plants of the D. elatum L. `Barbara' series were grown under either long- or short-day photoperiod, each treatment with or without receiving a soft-pinch. Time from planting to harvest was longer in pinched plants than in nonpinched plants of both cultivars regardless of photoperiod. Flowering stems were longer in hard- and soft-pinched plants of `Völkerfrieden' compared to nonpinched plants, and with `Barbara', stem length of pinched plants was either longer or similar to that of nonpinched plants regardless of photoperiod. At 30 days after the commencement of harvest, yield of flowering stems for hard-pinched plants of `Völkerfrieden' was higher than that for nonpinched plants, but yield from soft-pinched plants was similar to that for those not pinched. Stem yield for `Barbara' was higher for pinched plants under the long-day photoperiod, but under short days, yield from pinched plants was similar to that for those not pinched. Long days appear to increase yield and reduce production time in delphinium cultivars. Commercial benefits may be realized by growing nonpinched plants for earliness and pinched plants for longer stems and higher yield.
Research to determine protocols for greenhouse forcing of woody shrubs was initiated as part of the New Crop Research program at the University of Georgia. About 15 woody taxa were initially selected for the program based on habit, foliar qualities and flowering (if present). All plants were subjected to 1.7–4.4 °C for 0, 6, or 10 weeks in a controlled temperature cooler. Based on growth and visual characteristics, Leptodermis oblonga, Indigofera pseudotinctoria `Rose Carpet', Forsythia ×intermedia `Golden Peep' and Philadelphus coronaria `Manteau d'Hermaine' was discarded. Caryopteris x clandonensis `Sunshine Blue', Leycesteria formosa `Golden Lanterns', Sambucus nigra`Black Lace', Philadelphus coronaria`Variegata' and Physocarpus oblongifolius `Summer Wine' were investigated further. Data presented for Physocarpus suggested that cooling was not necessary for growth; however, 10 weeks of cooling resulted in the least time to finish in the greenhouse. Ten, six, and zero weeks cold resulted in 17, 10, and 7 weeks finish time respectively. Additional work conducted in 2005 and future research will be discussed.
As part of the New Floriculture Crop Program at the University of Georgia, a research project was initiated in Fall 2004 to determine the suitability of woody shrubs for forcing in the greenhouse. This paper will provide an overview of the research, indicating plants that were determined to be suitable for greenhouse forcing and sales in the retail area and those that were discarded from the program. About 15 taxa were initially selected for the program based on habit, foliar qualities, and flowering (if present). All plants were subjected to 1.7 °C to 4.4 °C for 0, 6, or 10 weeks in a controlled temperature cooler. Based on growth and visual characteristics, Leptodermis oblonga, Indigofera pseudotinctoria `Rose Carpet', Forsythia×intermedia `Golden Peep', and Philadelphus coronaria `Manteau d'Hermaine' were discarded. Caryopteris × clandonensis `Sunshine Blue', Leycesteria formosa `Golden Lanterns', Sambucus nigra `Black Lace', Philadelphus coronaria `Variegata', and Physocarpus oblongifolius `Summer Wine' were investigated further. Data presented for Physocarpus suggested that cooling was not necessary for growth; however, 10 weeks of cooling resulted in the least time to finish in the greenhouse. Zero, 6, and 10 weeks cold resulted in 17, 10, and 7 weeks finish time, respectively. Additional work on Kolkwitzia, Buddleia, and Wegelia conducted in 2005 and future research will be discussed.
As part of the New Floriculture Crop Program at the University of Georgia, a research project was initiated in Fall 2004 to determine the suitability of 12 taxa of woody shrubs for forcing in the greenhouse. In this study, the influence of cooling on greenhouse forcing of (Caryopteris×clandonensis `Sunshine Blue', Leycesteria formosa `Golden Lanterns' and Sambucus nigra `Black Lace') was evaluated. Dormant rooted liners were cooled for 0, 6, or 10 weeks at 1.7 °C to 4.4 °C. With 0 and 6 weeks cooling, Caryopteris never reached an acceptable finish stage. With 10 weeks cooling, plants finished in 7 weeks in the greenhouse. With 0 weeks cooling, Leycesteria was salable in 13 weeks. With 6 and 10 weeks cooling, plants finished in 7 and 8 weeks, respectively. With 0 weeks cooling, Sambucus never reached a salable stage. With 6 weeks cooling, plants were salable in 11 weeks; with 10 weeks cooling, plants finished in 6 weeks. The data suggest that cold is necessary to force Caryopteris and Sambucus in the greenhouse, and that 10 weeks of cold resulted in the shortest production time for both taxa. Data show that 6 weeks cooling of Leycesteria resulted in the shortest production time, but cooling is not necessary. This experiment was repeated in 2005–06 and will be compared to the 2004 findings. Additional experiments conducted in 2006 will also be discussed.
Zantedeschia aethiopica (L.) K. Spreng. `Childsiana' is a dwarf white calla lily with potential for pot culture. Nine stages of flower development from macrobud to senescence were described and shelf life under a low-light postproduction environment was examined. Flowers at the macrobud stage opened in the postproduction environment. Plants with flowers at the macrobud stage (Stage 1) and plants with spathes fully opened but before pollen shed (Stage 5) had shelf lives of 26 and 11 days, respectively.
Tissue culture is a useful means to clonally propagate new ornamental plant selections, particularly when plant material is limited and/or conventional propagation methods are ineffective. An efficient in vitro multiplication protocol was established to propagate a new goatsbeard hybrid (Aruncus dioicus, × A. aethusifolia). The hybrid is of interest because it exhibits a dwarf habit, delicate white flower panicles and fern-like leaves, yet is tolerant to heat and humidity. Experiments were conducted to evaluate explant type (nodes, stems, leaves, and floral parts), disinfestation procedures, and media formulations including varying concentrations of 6-benzylaminopurine (BAP) and naphthalene acetic acid (NAA). Rapid plant regeneration was obtained with a shoot organogenesis system using a half strength Murashige and Skoog medium supplemented with 4.4 μmol BAP, 0.54 μmol NAA, 30 g·L-1 sucrose, and 3.0 g·L-1 GelGro. Studies compared the performance and yield of plants rooted using different in vitro and ex vitro methods. Ex vitro rooting of shoots during greenhouse acclimatization under mist was most effective. Regenerated plants exhibited uniform and rapid growth, and performed well in greenhouse and field evaluations.
Aruncus `Misty Lace is a new hybrid selection between Aruncus dioicus and A. aethusifolius. The plants outstanding characteristics include heat tolerance, dwarf stature, and delicate, plume-like flowers. The objectives of this study were to evaluate the effect of different production parameters (chilling duration, container size, and photoperiod) on flowering in this new genotype Tissue cultured plantlets of Aruncus `Misty Lace' were transplanted to 72- or 36-cell trays and to 10-cm pots. Transplanted materials remained on the greenhouse bench until roots were visible in the soil plug, then placed in a cooler at 2-4 °C for 0 (control), 4, 6, 8, 10 and 12 weeks of chilling. Upon removal, plants were placed in a greenhouse in 10-cm containers under long or short day photoperiods until flowering, or until the experiment was terminated. Plants required less time on the bench to flower as cooling time increased, regardless of container size. Plants flowered earlier under long days than short days, but photoperiod was less of a factor in the control of flowering than cooling duration. Death of plants was greatest in the 72-plug cells and least in 10-cm pots. Plants without well established root growth sustained significant losses, regardless of container size.
Lysimachia congestiflora Wils. (Primulaceae) is a new crop for American nurseries and may be used as an annual in the north and a half-hardy perennial in the south. The purpose of this study was to investigate the influence of photoperiod, temperature, and irradiance on its flowering and growth. Three experiments were conducted with photoperiod of 8, 12, 16 hrs day-1, temperature of 10, 18, 26C, and irradiance of 100, 200, 300 μmol m-2s-1, respectively. Plant.9 given long day photoperiod (16 hours) flowered 21 and 34 days earlier, respectively, than plants at 12 sad 8 hour photoperiods. Plants under long day treatment produced more flowers than those at 8 and 12 hours. Plant dry weight did not differ between treatments, but plants grown in the long day treatment produced fewer but larger leaves. Total plant growth increased as temperature increased, but lower temperature (10C) decreased flower initiation and prevented flower development, while high temperature (26C) reduced the longevity of the open flowers. Flowering was accelerated and dry weight increased as plants were subjected to high irradiance levels. The results suggest that Lysimachia congestiflora is a quantitative long day plant. It should be grown under a photoperiod of at least 12 hours at a temperature of approximately 20C. Low light areas should be avoided and supplemental lighting to provide the long days may improve the plant quality.