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Rosanna Freyre and Sandra B. Wilson

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Sandra B. Wilson and Mack Thetford

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Sandra B. Wilson and Luke Flory

An interactive plant key was developed as an online tool with the specific goal of improving student learning of botanical vocabulary, plant morphology, and plant families. The online tool provides two options for using the multiple-entry key: identification of plant families based on historic botanical illustrations or live plant samples. The database consists of 196 angiosperm families, each with up to 220 botanical characters, and includes all of the plant families found in Florida. The tool uses a ternary system to record the diversity within each plant family such that upon entering identification information, families are eliminated that do not contain specific characters, which narrows the list of possible correct families. The remaining families are ranked according to total score, so families in which the features are common will appear first. This versatile online tool can be used nationwide to supplement in-person laboratory courses or distance education classes in horticulture, botany, systematics, and biology. To date, the newly launched site has been accessed by 1148 unique visitors from 15 countries.

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Sandra B. Wilson and Helen E. Danielson

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Sandra B. Wilson and Gary W. Knox

Japanese silver grass (Miscanthus sinensis) and 14 cultivars were transplanted in northern and southern Florida and evaluated for landscape performance, flowering, growth, and seed viability. All plants survived the 84-week study at both locations with the exception of `Morning Light', where 22% to 33% of the plants died. In northern and southern Florida, `Arabesque', `Adagio', `Cosmopolitan', and `Gracillimus' received the highest visual quality ratings on average throughout the entire study, yet other cultivars such as `Central Park' and `Silberfeder' performed well but had much narrower windows of peak performance. Cultivars such as `Little Kitten' and `Sarabande' performed far better in southern Florida than in northern Florida. Regardless of location, `Morning Light' and `Puenktchen' generally did not perform as well as other cultivars. In northern Florida, four consecutive months of very good to excellent flowering (75% to 100% canopy coverage) were observed for `Adagio', `Arabesque', `Cosmopolitan', `Gracillimus', `Little Kitten', `Sarabande', `Silberfeder', and `Zebrinus'. However, in southern Florida, peak flowering periods for these cultivars were delayed and generally only lasted for 1 to 2 months. On average, plants in northern Florida were larger and produced 2.8 times more flowers than plants in southern Florida. All cultivars produced viable seed with germination of viable seed ranging from 53.6% (`Cabaret') to 100% (`Gracillimus') in southern Florida, and from 49.8% (`Arabesque') to 100% (`Adagio', `Little Kitten', `Sarabande', and `Variegatus') in northern Florida.

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Jeongwook Heo, Sandra B. Wilson and Toyoki Kozai

An improved forced ventilation micropropagation system was designed with air distribution pipes for uniform spatial distributions of carbon dioxide (CO2) concentration and other environmental factors to enhance photoautotrophic growth and uniformity of plug plantlets. Single-node stem cuttings of sweetpotato [Ipomoea batatas (L.) Lam. `Beniazuma'] were photoautotrophically (no sugar in the culture medium) cultured on a mixture of vermiculite and cellulose fibers with half-strength Murashige and Skoog basal salts in a scaled-up culture vessel with an inside volume of 11 L (2.9 gal). CO2 concentration of the supplied air and photosynthetic photon flux on the culture shelf were maintained at 1500 μmol·mol-1 and 150 μmol·m-2·s-1, respectively. Plantlets grown in forced ventilation systems were compared to plantlets grown in standard (natural ventilation rate) tissue culture vessels. The forced (F) ventilation treatments were designated high (FH), medium (FM), and low (FL), and corresponded to ventilation rates of 23 mL·s-1 (1.40 inch3/s), 17 mL·s-1 (1.04 inch3/s), and 10 mL·s-1 (0.61 inch3/s), respectively, on day 12. The natural (N) ventilation treatment was extremely low (NE) at 0.4 mL·s-1 (0.02 inch3/s), relative to the forced ventilation treatments. On day 12, the photoautotrophic growth of plantlets was nearly two times greater with the forced ventilation system than with the natural ventilation system. Plantlet growth did not significantly differ among the forced ventilation rates tested. The uniformity of the plantlet growth in the scaled-up culture vessel was enhanced by use of air distribution pipes that decreased the difference in CO2 concentration between the air inlets and the air outlet.

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Sandra B. Wilson and Nihal C. Rajapakse

Plant response to photoselective plastic films with varying spectral transmission properties was tested using lisianthus (Eustoma grandiflorum) `Florida Pink', `Florida Blue', and `Florida Sky Blue'. Films were designated YXE-10 (far-red light-absorbing film) and SXE-4 (red light absorbing film). Light transmitted through YXE-10 films reduced plant height compared to control plants by 10% (`Florida Blue'), and stem dry weight by 19% to 40%, but the response varied by cultivar. Internode length was reduced by 10% to 19% when `Florida Pink' and `Florida Sky Blue' plants were grown under YXE-10 films. Leaf and root dry weights were not affected by YXE-10 films, with the exception that `Florida Sky Blue' plants had a lower leaf dry weight than the control plants. Light transmitted through SXE-4 films increased plant height of `Florida Pink' plants by 15% but not of `Florida Blue' or `Florida Sky Blue.' Regardless of cultivar, dry weight of leaf, stem and root tissue was not affected by SXE-4 films as compared to control films. The average number of days to flower and bud number were not affected by YXE-10 or SXE-4 films, regardless of cultivar. The results suggest that selective reduction of far-red wavelengths from sunlight may be an alternative technique for greenhouse production of compact plants, but the magnitude of the response is cultivar specific.

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Milton E. Tignor and Sandra B. Wilson

Information is more accessible to students than ever before. Gone are the days of a single instructor being the ultimate authority on a specific scientific discipline. Search engines, online journals, virtual libraries, and the development of Internet II will continue to drive the increase in availability of information. With basic computer skills, the average college student can put their hands on more subject data than they could possibly read during the time frame of a semester-long course. Therefore, it is more critical than ever to give students the logical tools to evaluate information and construct intelligent arguments. One particular area of interest to the horticulture industry is the impact of environmental regulations and public concern over common horticultural production practices such as irrigation, land development, application of pesticides, and developmental manipulation using growth regulators. South Florida is a mosaic of pristine natural areas, major agricultural production regions, densely populated urban areas, and regions of rapid suburban growth. As a result, there is heightened public awareness of environmental issues, which often leads to spirited conflicts among people with diverse professional backgrounds and personal interests. This catalyzed the development of a new course entitled “South Florida Flora and Ecosystems” that uses several different types of critical thinking exercises to help relate course content information into the cultural and political framework of South Florida. Techniques such as role playing, utilizing guest speakers with opposite opinions on the same topic, and active evaluation of data were used to enhance student learning, increase environmental awareness, and place undergraduate horticultural students one step closer to becoming “society-ready” graduates.

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Sandra B. Wilson and Peter J. Stoffella

Peat is used extensively in the nursery industry as a primary component in commercial “soilless” potting media. The increased use of peat as an organic amendment with superior water-holding capacity is challenged by economic and environmental pressures. Developing inexpensive and nutrient-rich organic media alternatives can potentially reduce fertilization rates, irrigation rates, and ultimately, nursery costs. In addition, controversy over the effects of peat mining has inspired a national search for peat substitutes. With our burgeoning population, it is logical to screen waste products as potential alternatives to peat. Growth of Pachystachys lutea Nees. (Golden Shrimp Plant) transplants was evaluated in media containing 0%, 25%, 50%, 75%, or 100% compost derived from biosolids and yard trimmings. Compost was amended with a commercial peat- or coir-based media. As compost composition in the peat or coir-based media increased from 0% to 100%, carbon/nitrogen (C/N) ratios decreased, and media stability, N mobilization, pH, and electrical conductivity (EC) increased. Bulk density, particle density, air-filled porosity, container capacity, and total porosity increased as more compost was added to either peat- or coir-based media. Plants grown in media with high volumes of compost (75 or 100%) had reduced leaf area and reduced shoot and root DW than the controls (no compost). Regardless of percentage of compost composition in either peat or coir-based media, all plants were considered marketable after 8 weeks.

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Sandra B. Wilson and Dennis R. Decoteau

Similarities exist between the effects of phytochrome and cytokinins on plant growth and development (e.g., chloroplast development, amaranthin synthesis, seed germination). It is unclear, however, if and how these two systems interact. The coaction between phytochrome and cytokinins was investigated by using Nicotiana plumbaginifolia plants transformed with the isopentenyl transferase (ipt) cytokinin gene and treated with end-of-day (EOD) red (R) and far-red (FR) light. The ipt gene was under control of either a constitutive cauliflower mosaic virus promoter (35S-plants) or an inducible, heat shock promoter (HS-plants). When treated with EOD FR light, whole plants were characterized by decreased chlorophyll concentrations and increased fresh weights. When treated with EOD R light, 35S-plants contained high concentrations of zeatin riboside (ZR) compared to plants treated with EOD FR light. When treated with EOD FR light, HS-plants contained high concentrations of ZR compared to plants treated with EOD R light. Both cytokinin responses were photoreversible. The reasons for the differences between the 35S- and HS-plant responses are not known. Results appear to implicate interactions between phytochrome and cytokinins in plant growth and development.