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Richard H. Mattson*, Eunhee Kim, Gary E. Marlowe, and Jimmy D. Nicholson

At the Lamar County Adult Probation Program in Paris, Texas, a three-year study (Spring 2001-Fall 2003) involving 376 probationers was conducted to investigate the rehabilitative effects on probationers of a horticulture vocational training program. Data were collected on 189 adults who were randomly assigned to a horticulture group doing greenhouse plant production and vegetable gardening activities. The horticulture group was compared with 187 adults who were in a non-horticulture community service group doing trash clean-up and janitorial work. Within the horticulture group, significant improvement occurred in horticultural knowledge (KSU General and Specific Horticulture Exams), self-esteem (Rosenberg Self-Esteem Scale), and environmental awareness (Environmental Response Inventory). These changes did not occur within the non-horticulture community service group. Future research will examine recidivism rates and vocational placements of probationers from both groups.

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Helen Beaufort-Murphy

Yield and insect damage of 50 potato cultivars, representative of genetic variation found in CIP germplasm collection, were evaluated over two years in a wide range of environmental conditions throughout Peru, from 4°S to 17°S, including coastal desert, cool highland and humid jungle, at altitudes from 180m to 3280m. Storage root and foliage yields were related to maximum and minimum temperature, photoperiod, precipitation, soils, and insect damage. Genotypic yield varied considerably from one location to another. Jonathan (Peruvian cultivar) produced well in Cañete (coastal desert) but not in the jungle or highlands. Jewel (US cultivar) produced well in Yurimaguas (jungle) but not in coastal deserts. Pesticides were not used but several cultivars had little or no insect damage, others were badly damaged. Some cultivars produced a reasonable yield over a wider range than did others. Results suggest that a cultivar can be strongly adapted to a particular set of environmental conditions. Data provide valuable information for growers-breeders.

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L. Art Spomer, Sharon L. Knight, and Mary Ann Lila Smith

Horticulture Research Methodology courses are an important if not essential introduction to research for beginning graduate students. Such courses are often characterized by presentation of a series of experimental techniques, lacking continuity and out of context with real-world research situations. In the described course, students gained expertise with a range of environmental and plant measurement techniques within the framework of a semester-long experiment. The experimental techniques were introduced and incorporated into the experiment at appropriate stages. Each student engaged in hands-on participation in development of a proposal; experimental set up, implementation, and daily maintenance; and data accumulation, analysis, and reporting (in HortScience manuscript format). In addition to direct experience with all subject techniques, each student had individual responsibility for characterization of a. selected plant (or environmental) parameter. This format successfully accomplished the provision of direct and coherent experience with a wide variety of important horticultural research techniques within a real-world setting.

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Hiroshi Shimizu, Erik S. Runkle, and Royal D. Heins

A model was constructed to predict shoot-tip temperature of poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) according to an energy-balance equation by using five greenhouse environmental factors: dry-bulb, wet-bulb, and sky (glazing or shade screen) temperature; transmitted shortwave radiation; and air velocity. An experiment was conducted to collect the five environmental variables that were used as model inputs, and shoot-tip temperature data were used to validate the predicted shoot-tip temperature in a commercial greenhouse. The standard deviation of the difference between predicted and measured shoot-tip temperature was 0.798 and was calculated by using 8547 data points, and >84% of the actual and predicted data points were within 1 °C. A sensitivity analysis performed with the model indicated that, among the three temperatures measured, plant shoot-tip temperature was primarily influenced by the dry-bulb temperature. For example, shoot-tip temperature increased an average of 0.74 °C for every 1 °C increase in dry-bulb temperature when dry-bulb temperature varied from 28 to 42 °C, wet-bulb temperature was 27.8 °C, sky temperature was 39.8 °C, shortwave radiation (285 to 2800 nm) was 760 W·m-2, and air velocity was 0.44 m·s-1. Under these conditions and a dry-bulb temperature of 32.6 °C, an increase in shortwave radiation of 500 W·m-2 increased the shoot-tip temperature by an average of 3.3 °C. This developed model may be a useful tool to predict shoot-tip temperature and evaluate the effect of greenhouse environmental factors on shoot-tip temperature.

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Chenggang Wang, Rolf Färe, and Clark F. Seavert

In this paper we analyze the sources of variation in revenue per unit of trunk cross-sectional area (TCA) across a 0.87-ha block of 272 pear (Pyrus communis L.) trees in 2003. Revenue capacity efficiency associated with TCA provides an overall measure of nutrient deficiency and revenue inefficiency caused by environmental constraints in the fruit production process. Data envelopment analysis (DEA) is adopted to estimate revenue capacity efficiency and its components. The deficiencies of macro- and micronutrients are measured and optimal nutrient levels computed for each individual tree. These measures are aggregated for comparing between grids and between rootstocks.

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John M. Skelly, Don D. Davis, and Dennis R. Decoteau*

An Air Quality Learning and Demonstration Center has been developed within the Arboretum at Penn State Univ.. The Center provides opportunities where students (of all ages) and teachers (grade-school through to classes within the Univ.) can learn about air quality as one of our most important natural resources. A seasonally interactive display of air quality monitoring instrumentation, self guided walkways through gardens of air pollution sensitive plant species, innovative techniques for demonstrating the effects of air pollutants on plants, displays of recent research findings, industry supported displays of pollution abatement technologies, and a teaching pavilion are within the Center. A Pennsylvania Dept. of Environmental Protection air quality monitoring station with ozone, sulfur dioxide, nitrogen oxides, carbon dioxide, PM < 2.5 u mass and speciation samplers, and a complete meteorological station provide data on the immediate environmental parameters. These data are relayed to an LCD crystal display board that has been mounted on the outside of the monitoring building; visitors are able to see the various measures of the air quality on a real time basis. Pannier type fiberglass display panels provide understandings of the various facets of air pollution formation and transport phenomena, air quality monitoring methods, the functions of open-top chambers, foliar symptoms expressed by pollution sensitive plants within the bioindicator gardens, and the impacts of pollution on agricultural and forested ecosystems. Handicapped accessible walkways lead visitors throughout the Center to the Teaching Pavilion that easily accommodates 80 persons. The pavilion is equipped with drop down curtains, electric power, and internet connections.

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M.W. van Iersel and B. Bugbee

Long-term, whole-crop CO2 exchange measurements can be used to study factors affecting crop growth. These factors include daily carbon gain, cumulative carbon gain, and carbon use efficiency, which cannot be determined from short-term measurements. We describe a system that measures semicontinuously crop CO2 exchange in 10 chambers over a period of weeks or months. Exchange of CO2 in every chamber can be measured at 5 min intervals. The system was designed to be placed inside a growth chamber, with additional environmental control provided by the individual gas exchange chambers. The system was calibrated by generating CO2 from NaHCO3 inside the chambers, which indicated that accuracy of the measurements was good (102% and 98% recovery for two separate photosynthesis systems). Since the systems measure net photosynthesis (Pnet, positive) and dark respiration (Rdark, negative), the data can be used to estimate gross photosynthesis, daily carbon gain, cumulative carbon gain, and carbon use efficiency. Continuous whole-crop measurements are a valuable tool that complements leaf photosynthesis measurements. Multiple chambers allow for replication and comparison among several environmental or cultural treatments that may affect crop growth. Example data from a 2 week study with petunia (Petunia ×hybrida Hort. Vilm.-Andr.) are presented to illustrate some of the capabilities of this system.

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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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E.W. Stover and D.W. Greene

Plant response to foliar application of plant growth regulators (PGRs) is often variable, in part due to environmental factors. Weather prior to application is thought to influence cuticle development and thus PGR uptake. For example, in growth chamber studies foliar uptake of 1-naphthaleneacetic acid (NAA) is sometimes increased when fruit trees are placed in low temperature and high humidity several weeks prior to application. Environmental conditions over an extended period of time after application may influence PGR conversion to active form (e.g., ethephon), PGR metabolism, or metabolic factors that affect PGR activity in the plant. The effects of environmental conditions on PGR uptake have been investigated extensively in laboratory studies. In many cases, uptake is clearly increased by high temperatures immediately after application. Laboratory studies report a linear positive correlation between temperature and uptake and greater temperature response above 25 °C (77.0 °F). High humidity and longer drying time often are also reported to increase PGR uptake in laboratory studies. These results are consistent with many grower observations on effects of weather on chemical thinning and have been incorporated into many product labels and extension recommendations. However, relatively few field experiments have been reported in which the relationship between PGR response and environmental conditions were assessed. Wash-off studies have demonstrated that rain shortly after application may reduce efficacy of NAA. Several studies demonstrate environmental interaction with metabolic activity involved in PGR action. For example, shading after thinner application is reported to increase fruitlet abscission and enhance effectiveness of some thinning agents. Chemical thinning of apples (Malus ×domestica) with ethephon is reported to correlate strongly with temperature in the days after application, while studies suggest that higher temperatures after aminoethoxyvinylglycine (AVG) application may reduce control of preharvest drop. However, the stage of fruitlet development at apple thinning often appears to be more important than environmental conditions at the time of PGR application. In addition, field experiments indicate that longer drying times at lower temperatures seem to largely compensate for greater uptake rates at higher temperatures. This paper discusses data from published and previously unpublished experiments in order to understand the effects of environment on PGR response variability.

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Leslie K. Lake, Warren E. Shafer, Sheryl K. Reilly, and Russell S. Jones

Plant growth regulators (PGRs) are often used in crop production for specific niche market needs. PGRs are frequently viewed as secondary business opportunities by the private sector, especially when compared to herbicide, insecticide, and/or fungicide markets. Nonetheless, PGRs are regulated by the U.S. Environmental Protection Agency (USEPA), and the additional cost of regulatory compliance as part of commercial development is significant. Of the two broad classes of pesticides regulated by the USEPA, conventional chemicals and biological pesticides (or biopesticides), many PGRs belong to the biopesticide class, specifically the biochemical category. Because of USEPA's responsibility to assure that any pesticide used in commerce will not result in unreasonable adverse effects to humans or the environment, specific data requirements have been established for product registration. Registrants must address each requirement, either by submitting relevant data or a request to waive the requirement, prior to receiving a federal registration. For biochemical PGRs, the acceptability of data or waiver requests, as well as any proposed label uses, are reviewed by the Biopesticides and Pollution Prevention Division (BPPD). The BPPD was formed in 1994 to facilitate the development of biopesticide products. Given the time and expense associated with PGR product development and commercialization, registrants should work closely with the USEPA and other stakeholders to help ensure successful product development.