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Gina E. Fernandez, Laura M. Butler, and Frank J. Louws

Strawberry (Fragaria × ananassa) `Chandler' plants from three sources were grown in the annual hill plasticulture system during two growing seasons (1996-97 and 1997-98). These trials evaluated the yield and vegetative performance of bareroot plants from Prince Edward Island and Ontario, Canada, and plug plant tips that were rooted in North Carolina but obtained from Ontario Canada. At the end of the season, total and marketable yields and fruit weight were not different among the plant sources. In addition, plants from all three plant sources produced equivalent yields on a weekly basis. Monthly whole plant harvests revealed that plant source did not affect leaf area, root, crown, leaf, flower or fruit dry weight during most of the growing season. In addition, plant growth parameters (specific leaf area, leaf area ratio, leaf weight ratio, and root to shoot ratio) in general did not differ among plant source in any 1 month. Plant growth did show shifts in dry weight allocation and leaf area as the season progressed that were uniform among plant sources, with the majority of the growth occurring in the spring in the two months prior to harvest. This uniformity among plant sources will allow future research to emphasize plant production practices that may reduce the risk of pest and disease problems or optimize production practices favored by growers.

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Pietro Santamaria and Antonio Elia

In a growth chamber, endive (Cichorium endivia L. var. crispum Hegi) plants were grown using a solution culture method to evaluate the influence of four ammonium : nitrate (NH4-N : NO3-N) percentage ratios (100:0, 70:30, 30:70, and 0:100) on growth (leaf area, dry mass, crop growth rate, relative growth rate, and net assimilation rate), yield characteristics (head and root fresh mass and root length), quality (dry matter, nitrogen, and nitrate), and inorganic ion content. No symptoms of NH4 + toxicity were detected in endive plants 8 weeks after beginning nutrient treatments. Moreover, by feeding N in mixed form, the growth indices increased compared to indices from feeding with any of the two N forms alone. Ammonium-fed plants produced nitrate-free heads with a fresh mass (171 g) similar to nitrate-fed plants. Compared to the other treatments, the heads of NH4 +-fed plants were darker green and more succulent. Mixed N improved yield but caused a remarkable accumulation of nitrate in heads. Following an increase in NO3-N from 30% to 70% in the nutrient solution, head fresh mass rose from 196 to 231 g and NO3 - concentration more than doubled (from 2.4 to 6.1 g·kg-1 fresh mass). With 100% of NO3-N, NO3 - concentration was 5.5 g·kg-1 fresh mass. With higher NO3-N percentages in the nutrient solution, the difference in the concentration of inorganic cations and anions increased, but K+ concentration was also high in ammonium-fed plants (on average 77 g·kg-1 dry mass). Head total N accumulation was increased by the presence of NH4 + in the nutrient solution and decreased with 100% NO3-N. From the commercial viewpoint, the produce obtained from 100% NH4-N was good, with the value-added factor of the absence of nitrate. This may be an extremely remarkable factor because of the commercial limits on the allowable nitrate content in leafy vegetables already enforced by many European countries and those the European Union is going to adopt in a directive.

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Joyce G. Latimer and Reuben B. Beverly

Brushing (40 strokes per 1.5 minutes, twice daily) or moisture stress conditioning (MSC) (daily nonlethal dry-down cycles) reduced seedling growth of two cucumber (Cucumis sativus L.) cultivars in 1991 and three squash (Cucurbita pepo L.) cultivars in 1991 and 1992. In both years, watermelon [Citrullus lanatus Thunb. (Matsum. & Nakai)] cultivars varied in responsiveness to brushing; brushing reduced stem length 0% to 44% over four cultivars in 1992. MSC reduced growth of all cultivars. Brushing increased the rate of water loss from detached leaves of cucumber, squash, and watermelon, whereas MSC decreased water loss from leaves of cucumber and squash. In 1991, under well-watered posttransplant conditions, MSC increased the mean relative growth rate (RGR) of cucumber and watermelon transplants in the greenhouse. Brushing increased the RGR of watermelon transplants. In 1992, MSC increased the RGR of squash and watermelon transplants grown under posttransplant drought-stressed conditions, while brushing had no effect. Both conditioning treatments controlled plant growth in the greenhouse without diminishing subsequent plant performance.

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Susan Kreder and Albert H. Markhart III

Environmental conditions are known to affect the growth and quality of culinary and medicinal herbs. Hydroponic growing conditions often produces greater yields for many leafy crops compared to growth in more-traditional media. The objective of this investigation was to compare the yield and quality of sweet basil grown in continuous flow solution culture or well-irrigated Universal Mix. Sweet basil plants were germinated under mist and then transplanted to a continous-flow hydroponics system or to 6-inch pots containing Universal Mix. Rows of pots alternated with a row of hydroponic plants in a temperature-controlled greenhouse. Temperatures were maintained between 20 and 25 °C, the relative humidity was not controlled, pot-grown plants were irrigated as needed. HID lights added sublimentry irradiation and maintained a photoperiod of 18 h. Cohorts of plants were harvested at five time points between transplanting and maturity. Plants were divided into leaves, stems, and roots, dried, and the data subjected to mathmatical growth analysis. Several leaves from each plant were harvested and analyzed by gas chromotograpth for essential oils. Plants grown in hyroponics grew faster and produced more harvestable leaf material than the media-grown plants. Details of the plant growth analysis and the essential oil composition will be presented.

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D. Marshall Porterfield, Mary E. Musgrave, and Thomas W. Dreschel

A ground-based comparison of plant nutrient delivery systems that have been developed for microgravity application was conducted for dwarf wheat (Triticum aestivum L. `Yecora Rojo') and rapid-cycling brassica (Brassica rapa L. CrGC#1-33) plants. These experiments offer insight into nutrient and oxygen delivery concerns for greenhouse crop production systems. The experiments were completed over a 12-day period to simulate a typical space shuttle-based spaceflight experiment. The plant materials, grown either using the porous-tube nutrient delivery system, the phenolic foam support system, or a solidified agar nutrient medium, were compared by plant-growth analysis, root zone morphological measurements, elemental composition analysis, and alcohol dehydrogenase enzyme activity assay. The results of these analyses indicate that the porous tube plant nutrient delivery and the phenolic foam systems maintain plant growth at a higher level than the solidified agar gel medium system. Root zone oxygenation problems associated with the agar system were manifested through biochemical and morphological responses. The porous tube nutrient delivery system outperformed the other two systems on the basis of plant growth analysis parameters and physiological indicators of root zone aeration. This information is applicable to the current crop production techniques used in greenhouse-controlled environments.

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Justine E. Vanden Heuvel, J. Alan Sullivan, and John T.A. Proctor

Treatments of either staked (stabilized) or not staked (control, freestanding) canes were applied to Rubus idaeus L. `Boyne' and `Regency' during the 1997 and 1998 seasons to determine the effect of stabilizing fruiting canes in a windy environment. Treatments were applied in late April of each year, and canes were removed following harvest for growth analysis. Stabilizing (staking) floricanes increased yield per cane in `Boyne' by 68% and in `Regency' by 189%, primarily through increases in fruit number per cane. Leaf area of the staked canes was 41% larger for `Boyne' and 159% for `Regency' than that of the control canes, suggesting that more leaf area was retained for photosynthesis, resulting in greater yield. Primocane diameter in `Boyne' and primocane height in `Regency' were also increased by staking, but floricane structure was unaffected.

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Janice Smith, Charles Raczkowski, and Marihelen Kamp-Glass

Crop canopy cover data is used to study canopy structure and crop growth analysis. This study was conducted to determine the easiest and most reliable method of calculating crop canopy cover. Using Decagon Sunfleck Ceptometer was compared with the traditional method (tape measure) of retrieving crop canopy cover data. Data was collected on silage corn (Zea mays) and soybeans (Glycine max L.). The method of collecting data using the ceptometer was simple and quick compared to the traditional method. The ceptometer, even with human variability, was found to be ≈99% accurate. The traditional method was found to have >10% variability. The ceptometer is a much quicker and more reliable tool to use. It appears to decrease the variability in the collection of crop canopy cover data.

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Andrea Luvisi, Alessandra Panattoni, Roberto Bandinelli, Enrico Rinaldelli, Mario Pagano, Barbara Gini, Giorgio Manzoni, and Enrico Triolo

Plant tagging using radiofrequency identification (RFID) microchips is attractive for ornamental shrubs, such as rose (Rosa spp.), due to their high market value, wide distribution, health certification system, and numerous uses. Differently from other woody species for which methods of microchip implantation have been tested, rose tagging requires the possibility of insertion within canes of less than 10 mm diameter, such as those typically found in the rose nursery setting. Moreover, the possibility of tagging after grafting without changing common plant production procedures and aesthetic value are important considerations. Toward this aim, a new method of microchip insertion was developed. To test its effects on roses, two cultivars were subjected to a tagging procedure, and histological observations of tissues around the microchip and growth analysis of plant canes were performed. Microchip implantation did not cause xylem necrosis in 8- to 9-mm-diameter canes, but in lower diameter canes wilt of the lateral shoot and detriments in growth were observed compared with control plants. The tagged roses were tracked by a database developed for rose information, field log, and botanical sheet retrieval. Our findings suggest that rose plants can be safely tagged with a RFID microchip following suitable selection of cane calliper as early as the nursery phase without negative effects on plant appearance.

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Brent L. Black and Richard H. Zimmerman

Bottom ash from a coal-fired power plant and two composts were tested as components of soil-free media and as soil amendments for growing highbush blueberry (Vaccinium corymbosum L.). Combinations of ash and compost were compared to Berryland sand, and Manor clay loam, and compost amended Manor clay loam. The pH of all treatment media was adjusted to 4.5 with sulfur at the beginning of the experiment. In 1997, plants of `Bluecrop' and `Sierra' were planted in 15-dm3 pots containing the pH-adjusted treatment media. The first substantial crop was harvested in 1999. At the end of the 1999 season, one half of the plants were destructively harvested for growth analysis. The remaining plants were cropped again in 2000. Yield and fruit size data were collected in both seasons, and leaf and fruit samples were collected in 1999 for elemental analysis. The presence of coal ash or composted biosolids in the media had no detrimental effect on leaf or fruit elemental content. Total growth and yield of both cultivars was reduced in clay loam soil compared to Berryland sand, whereas growth and yield of plants in coal ash-compost was similar to or exceeded that of plants in Berryland sand.

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Kent D. Kobayashi

How do we enhance the learning experience of graduate students in scientific writing, an essential skill in their professional development? A graduate course TPSS 711 “Scientific Writing for Graduate Students” was developed to address this need. Its objectives were to help students write, analyze, and revise parts of a scientific paper; critically evaluate their own writing and the writings of others; and become familiar with types of publications. The diverse topics included purpose of scientific writing; organizing your writing; parts of a scientific paper; data analysis and growth analysis; writing the content of a poster or oral presentation; newspaper articles and popular works; extension publications; technical writing for the general public; thesis/dissertation writing; a journal editor's perspective; and reviewing a manuscript. TPSS 711 had an enrollment of 11 TPSS master's students. Students were in their second through fifth semesters of their graduate program. A student survey showed no student had submitted a manuscript to a peer-reviewed journal, had a peer-reviewed article published, or had a newspaper, trade magazine, or popular work published. Only 9% of the students had a paper published in a conference proceedings or presented a scientific paper outside Hawaii, with only 18% having presented a paper in Hawaii. Writing assignments, in-class activities, and evaluations of the writings of others helped students gain intensive hands-on experience in scientific writing. As a course requirement, students submitted an abstract and presented a paper at our college's annual scientific symposium. Course evaluations indicated this course was important and valuable in helping enhance the students' learning experience.