bluuebunny/crossref_metadata_2025 huggingface dataset:
426 Deer Response to Selected Plant Extracts
Authors: Harris Christine E. , Simonne Eric , Codreanu Peggy , Eakes Joseph
Published: February 2019

Feeding damage by white-tailed deer to vegetable and ornamental crops are often adverse to plant growth, and result in economic and aesthetic losses. While the efficacy of commercially available deer repellent products is questionable, plant extracts may provide an environmentally sound alternative to traditional chemical treatments. Commercially available plant extracts (Dusty Miller, peppermint, Madagascar periwinkle, wax myrtle, barberry, juniper, geranium, rosemary, lemon balm, and yucca) known to be unpalatable plants were chosen as treatments. Thiram and putrescent egg spray were used as positive controls along with a no-spray treatment. Gomphrena were grown off-site in trade gallon pots and used as test plants. Sixteen deer were confined in two 1-acre study pens at the Auburn Univ. Deer Research Facility. Feeding damage was recorded daily using a 0 to 3 rating scale corresponding to 1/3, 2/3, and complete destruction, respectively. All damage data were converted into percent damage. Barberry and wax myrtle extracts made gomphrena more palatable to the deer as feeding damage exceeded that of the untreated plants. However, lemon balm, rosemary, yucca, and peppermint provide some level of protection against feeding damage to gomphrena. Fifth-day damage ratings for these extracts were 37%, 35%, 13%, and 19%, respectively. Fifth-day damage for untreated plants was 40%. Peppermint and yucca extracts appear to be promising alternatives to thiram and putrescent egg-based products.
428 Nitrogen Form Affects Growth, Mineral Nutrient Content, and Root Anatomy of Cotoneaster and Rudbeckia
Authors: Kraus Helen T. , Warren Stuart L.
Published: February 2019

Five ratios of NH4:NO3 (100:0, 75:25, 50:50, 25:75, and 0:100) were evaluated for impacts on growth of Cotoneaster dammeri Schneid. `Skogholm' (cotoneaster) and Rudbeckia fulgida Ait. `Goldsturm' (rudbeckia). Nitrate decreased dry weight and leaf area, while nutrient solutions containing >25% NH4 increased shoot and root growth of cotoneaster and rudbeckia. Additionally, NO3 decreased accumulation of some cationic nutrients and N in roots and shoots of cotoneaster and rudbeckia compared to solutions containing either NH4 alone or mixes of NH4 and NO3. Nitrogen contents (in milligrams) in cotoneaster fertilized with NO3 decreased an average of 54% and 58% in rudbeckia compared to N supplied as NH4 alone. These dramatic reductions in growth and tissue nutrient content reiterate the need for proper N form selection. Root diameter of cotoneaster was higher with a mix of NH4 and NO3 than with NO3 alone; whereas, the N form had no impact on diameter of rudbeckia roots. However, the stele of both cotoneaster and rudbeckia roots was larger and contained more secondary xylem with larger tracheary elements with a mix of NH4 and NO3 compared to nutrient solutions with NO3 alone. Increased number and size of secondary tracheary elements may relate to increased dry weight and leaf area of both cotoneaster and rudbeckia fertilized with mixes of NH4 and NO3 compared to NO3 alone.
429 Detecting Incipient Water Stress in Buffalograss and Kentucky Bluegrass through Foliage Temperature using Lowcost Infrared Sensors
Authors: Stewart J. Ryan , Kjelgren Roger
Published: February 2019

Infrared sensors were used to quantify canopy temperature and thus detect differences in incipient water stress between a cool-season grass [Kentucky bluegrass (KBG) (Poa pratensis)] and a warm-season grass [buffalograss (BG) (Buchloe dactyloides)]. The infrared sensors, connected to a datalogger, measured average hourly leaf–air temperatures (TL–TA) 1 m above eight replicate plots of Kentucky bluegrass and eight replicate plots of buffalograss. Air temperature and relative humidity from a nearby weather station were used to calculate the average hourly vapor pressure deficit (VPD). In late July, we ceased irrigating and measured TL–TA and soil water content while allowing the turf to dry down for 5 weeks. Soil water content was measured with a neutron probe. Both species exhibited a significant relationship between TL–TA and VPD. As the VPD increased, TL–TA decreased in both species (KBG r2 = 0.73, BG r2 = 0.71) on the 2nd day after an irrigation during well-watered conditions. An artifact was created on the first day after an irrigation as a result of excessive surface evaporation. KBG and BG were similar under well-watered conditions. KBG had a higher TL–TA after 4 to 5 days without irrigation. By contrast, BG did not have a higher TL–TA until 25 to 30 days without irrigation. Part of BG's drought avoidance was extraction of soil water down to 0.9 m vs. 0.45 m for KBG.
435 Seasonal Amplitude and Distribution of Elevated Atmospheric CO2 in Phoenix, Arizona, USA
Authors: Martin Chris A. , Stabler Linda B.
Published: February 2019

Combustion of fossil fuels in urban areas might increase local atmospheric CO2 concentrations and could result in an urban to rural CO2 concentration gradient. Our objective was to ascertain if such a CO2 gradient exists and to characterize seasonal patterns of amplitude and distribution of atmospheric CO2 concentrations in the Phoenix, Ariz., metropolitan, area. Atmospheric CO2 concentration was measured along a series of gradients that transected the greater Phoenix metropolitan area in June 1999, in Dec. 1999, and Jan. 2000. Carbon dioxide concentration was measured with a portable infrared gas analyzer in open system mode from a mobile vehicle traveling at a constant rate of speed. All measurements were made around 0500 and 1500 HR on days when weather conditions were clear and calm. The CO2 intake port was located above the vehicle at a height of 2.5 m. Data were categorized based on distance from the Phoenix urban core, defined as the intersection of Central Avenue and Van Buren Street. Gradients of high to low CO2 concentration existed from city center to outlying rural areas. Carbon dioxide concentrations were highest during winter and varied most during the afternoon. Mean CO2 concentrations in central Phoenix were 12% higher than surrounding rural areas during summer, but were up to twice as high as rural areas during winter. We conclude that there is a potential for atmospheric CO2 fertilization of plants in the Phoenix area, particularly of urban landscape plants that are biologically active during winter.
443 Resistance in Impatiens wallerana to Western Flower Thrips [Frankliniella occidentalis (Pergande)] Feeding Damage
Authors: Herrin B. Bejie , Warnock Daniel F.
Published: February 2019

Western flower thrips are an ever-increasing problem in greenhouse floriculture crops. Thrips resistance to pesticides as well as tighter regulations on pesticide use are making thrips management in the greenhouse more difficult. To improve host plant resistance, a study was conducted to determine if impatiens cultivars varied in their susceptibility to western flower thrips feeding damage. In a replicated study, nine impatiens cultivars were inoculated with about 30 thrips. Thrips were allowed to feed on individual plants during an 8-week period of growth. During plant growth, visual evaluations to estimate thrips feeding damage were conducted every 2 weeks. At the conclusion of the experiment, a final visual evaluation was made and thrips numbers were determined. Cultivars varied in estimates of thrips feeding damage. Several cultivars exhibited significantly reduced levels of thrips feeding damage. Of these cultivars, some had high thrips population levels, indicating tolerance, while other cultivars had low thrips population levels, an indication of antibiosis. One cultivar was determined to be highly susceptible to thrips feeding damage. This cultivar was so damaged by the end of the study, remaining plant material was unable to support thrips populations. Variability was found in the levels of thrips feeding damage and thrips population levels indicating the presence of tolerance and/or antibiosis. Because of detected variability, the potential for improving impatiens resistance to thrips feeding damages exists.
455 Yield and Yield Attributes of Onion Cultivars Grown in Arid Regions
Authors: Alsadon Abdullah A.
Published: February 2019

Eleven onion (Allium cepa L.) cultivars were selected to evaluate their yield performance under the arid conditions of the Riyadh area in the Central region of Saudi Arabia during the 1996–97 and 1997–98 growing seasons. The selected cultivars were: Colossal PVP 234, Contessa, Dorado, Red Creole, Ring Master, Rio Sultan, RioTalat, Texas Grano 502, Texas Early Grano 502, Und Grande and Yellow Spanish. Yield (ton/ha) and yield attributes such as bulb diameter, length, weight and dry matter were assessed. Transplants grown in plastic trays for 45 days under greenhouse conditions were transplanted in the field on 7 Jan. 1997 and on 29 Dec. 1997 and harvesting was carried out on 19 May 1997 and on 15 May 1998 for the first and second season, respectively. Significant differences were observed between cultivars and among growing seasons, with significant interaction for yield and bulb weight. The top high yielding cultivars in the first season were Und Grande, Texas Early Grano 502, Colossal PVP 234, Contessa and Dorado. In the second season, Dorado, Red Creole, Contessa, Ring Master and Und Grande outyielded other cultivars. Under the conditions of this study, Contessa, Dorado, Red Creole, Texas Early Grano 502, and Und Grande had the highest yield attributes that made them recommended for growing in the arid regions. The yield and yield attributes of each cultivar will be discussed.
467 Mapping Anthocyanin Pathway Genes in Raspberry
Authors: Weber Courtney A. , Boone William
Published: February 2019

The role of plant pigments in human health has been under intense scrutiny recently. Anthocyanin pigments have been shown to be powerful antioxidants and may contribute to other areas of human health. In red and black raspberry, Rubus idaeus and Rubus occidentalis, respectively, no less than eight different anthocyanin pigments have been identified. However, the genetics controlling the presence and ratios of the different pigments is poorly understood. Various researchers have identified four loci that impart fruit pigment deficiencies and three loci that affect the pigment ratios. The underlying gene function of these loci is not known. Efforts are under way to map two pigment deficiency loci in red raspberry using bulked segregant analysis. Screening with 800 random primers has produced two markers with >90% and two with >80% correlation to one loci. For the other loci, 10 markers with >80% correlation have been identified. Mapping is ongoing with the first linkage map for raspberry to be presented. Populations to test allelism between sources of pigment deficiency are being evaluated for further mapping of loci of the anthocyanin production pathway. Data on cloning of genes in the anthocyanin pathway based on database sequences with degenerative primers for further elucidation a anthocyanin production in raspberry will be presented.
468 Inheritance of Day Neutrality and Heat-delay Insensitivity in Dendranthema grandiflora Tzvelv.
Authors: Anderson Neil O. , Ascher Peter D.
Published: February 2019

Greenhouse and garden chrysanthemums are quantitative short-day (SD) plants for flower bud initiation (FBI) and qualitative (obligate) SD plants for flower bud development (FBD). Continuous or intermittent application of red light in the middle of the dark period (night), inhibits FBI. The chrysanthemum breeding program has been selecting for day-neutral (DN) types, i.e. that will undergo FBI and FBD under any photoperiod. The inheritance of DN was studied using six cultivars (n = 2 SD types, n = 4 DN types) that were crossed in a complete diallel over two crossing periods. Pollinations were replicated and ovules were counted. Histograms of self and cross seed set showed a distribution from 0% to 100%, with the majority of pollinations below 30%. Mean self seed set (2.6%) was less than the mean cross seed set (32.8%), indicating the presence of a self incompatibility system. Parents and F1 progeny were grown under LD conditions (red light, night interruption, 2200-0200 HR) and high temperatures (30 °C day/25 °C night, to screen for heat delay insensitivity). F2 progeny could not be generated due to self incompatibility. The fraction of flowering: non-flowering progeny and the number of days to first flower was recorded on the flowering individuals for comparison with the parents. Due to small progeny numbers, reciprocal crosses were bulked prior to Chi-square tests (1:1, 3:1, 1:3). The number of days to first flower ranged from 27 to 93+ in all progeny with significantly earlier and later outliers present. Most Chi-square tests were not significant, indicating that the inheritance of DN and heat delay insensitivity are not controlled by a single gene. Additive and epistatic effects may also be present.
483 Identification of S-RNase in Tetraploid Sour Cherry
Authors: Yamane H. , Tao R. , Sugiura A. , Hauck N. , Iezzoni A.
Published: February 2019

Most fruit tree species of Prunus exhibit gametophytic self-incompatibility, which is controlled by a single locus with multiple alleles (S-alleles). One interesting aspect of gametophytic self-incompatibility is that it commonly “breaks down” as a result of polyploidy, resulting in self-compatible individuals. This phenomenon is exhibited in the diploid sweet cherry (P. avium) and the tetraploid sour cherry (P. cerasus), in which most cultivars are self-compatible. Recently, S-gene products in pistil of Prunus species were shown to be S-RNases. As sour cherry is one Prunus species, it is likely to possess S-alleles encoding pistil S-RNases. To confirm this, we surveyed stylar extracts of 11 sour cherry cultivars, including six self-compatible and five self-incompatible cultivars, by 2D-PAGE. As expected, all 11 cultivars tested yielded glycoprotein spots similar to S-RNases of other Prunus species in terms of Mr, immunological characteristics, and N-terminal sequences. A cDNA clone encoding one of these glycoproteins was cloned from the cDNA library constructed from styles with stigmas of a self-compatible cultivar, `Erdi Botermo'. Deduced amino acid sequence from the cDNA clone contained two active sites of T2/S type RNases and five conserved regions of rosaceous S-RNases. In order to determine the inheritance of self-incompatibility and S-allele diversity in sour cherry, we conducted genomic DNA blot analysis for sour cherry germplasm collections and mapping populations in MSU using the cDNA as a probe. To date, it appears as if self-compatibility in sour cherry is not simply controlled by a self-fertile allele as demonstrated in other Prunus species.
498 Increasing Postproduction Quality and Longevity of Flowering Potted Plants
Authors: Nell Terril A. , Leonard Ria T. , Barrett Jim E. , Clark David G.
Published: February 2019

Production and postproduction factors were examined to evaluate effects on postproduction performance and longevity of several varieties of potted African violets, carnations, chrysanthemum, cyclamen, gerbera, Hiemalis begonia, hibiscus, hydrangea, kalanchoe, and lisianthus. Various N rates (150–600 ppm) and fertilizer termination 2 to 3 weeks prior to flowering were evaluated. Chrysanthemums, hydrangea, and lisianthus had better quality and longevity at N rates ranging from 200 to 300 ppm, while all other crops performed best at 150 ppm N. Terminating fertilizer had no effect on longevity or quality of carnation, gerbera, Hiemalis begonia, hydrangea, or kalanchoe, while chrysanthemum and cyclamen had a significant increase in longevity when terminated. Lisianthus had an increase in quality and longevity when fertilizer was continued to the end of production. Shipping at the proper bud developmental stage significantly influenced flower opening and longevity in the postharvest environment. Lisianthus and hydrangea need to have at least 75% of the buds fully opened, while carnations, chrysanthemum, cyclamen, and kalanchoe need at least 25% to 50% open. Hiemalis begonia, a very long-lasting potted plant, tolerated a range of 10% to 75% open flowers at shipping. Optimum transport temperature and transport duration varied for each crop. Generally, transporting for 3 days at 2 to 7 °C was best for carnation, chrysanthemum, and gerbera, while transporting at 7 to 12 °C was best for cyclamen, Hiemalis begonia, hydrangea, kalanchoe, and lisianthus. Hibiscus performed best when transported at 18 °C. Longevity and quality were maximized when maintained at 18 to 21 °C at 14 μmol·m–2·s–1. Differences in variety performance was a major factor in postproduction performance.
510 Impact of a Reduced Fungicide Program on `Liberty' Apple Tree Vigor, Productivity, and Fruit Quality
Authors: Berkett L.P. , Garcia M.E. , Clements J. , Neff G.
Published: February 2019

Apple scab, a fungal disease caused by Venturia inaequalis, is considered the most important disease of apple worldwide. The disease can be devastating, causing reduction in yield or making the apples unfit for the market. Currently, the production of marketable fruit from scab susceptible cultivars depends on the repeated applications of fungicides. Scab-resistant apple cultivars, which are genetically immune to apple scab, can offer a biological alternative to fungicide use. `Liberty,' was bred for immunity to apple scab; however, it is not immune to other apple diseases and pests. Research has been conducted during a 3-year project (1996–1998) to determine whether reduced fungicide programs adversely affect overall tree vigor, productivity, and fruit quality. Data collected include tree vigor (TCSA and time of leaf abscission), tree productivity (YE), and fruit quality (fruit firmness and disorders during storage). Results indicate no significant differences between the two treatments (reduced fungicide and no fungicide application) in most of the parameters measured. Based on fruit that were harvested and graded to commercial standards, the estimated gross monetary value of the crop does not show difference between treatments. These results could translate into an economic advantage for growers when one factors in the savings in fungicide purchases. In addition, there are also health and environmental advantages to reduced fungicide usage.
516 Does Diphenylamine Reduce Chilling Injury in Green Bell Peppers?
Authors: Purvis Albert C.
Published: February 2019

Diphenylamine has been used to reduce low-temperature-induced storage scald of apples for decades. Its effectiveness in reducing scald has been attributed to its antioxidant properties. Oxidative reactions have also been implicated in chilling injury of other commodities, including green bell peppers (Capsicum annuum L.). Diphenylamine was applied as a dip at rates of 500 to 2000 ppm to green bell peppers prior to storing them for 7 days at 1 °C. The development of sheet pitting, the most common visible symptom of chilling injury in bell peppers, was inhibited almost completely by diphenylamine. Diphenylamine, however, only slightly reduced the chilling-induced decrease in chlorophyll fluorescence ratios. Darkening of the vascular tissues of the calyxes and seed darkening, which are also symptoms of chilling injury, were not prevented by diphenylamine. Thus, diphenylamine either did not get into all of the sites of oxidative reactions or some of the manifestations of chilling injury are initiated by processes other than oxidative ones.
522 Cost Analysis and Perceived Value of Selected Landscape Features
Authors: Hardy Jill , Behe Bridget , Barton Susan , Page Thomas , Fernandez R. Thomas , Schutzki Robert , Rowe D. Bradley
Published: February 2019

For most residential home improvements, excluding landscapes, professionals can document return on investment. Our objective was to compare costs of installing landscapes with perceived home value, and determine return on investment. We administered surveys in eight selected U.S. cities in 1999. Self-selected participants from home and garden shows were asked to examine a photograph of a home without landscaping (base home), and were given its value estimated by local realtors. Participants were asked to view 16 additional photographs of the base home with different landscapes. Cost estimates for landscape materials and installation were calculated. Results showed that a sophisticated landscape with large and diverse plant material added up to 13% to the perceived value of a new $200,000 home. On average, any level of landscaping added value to the home. The increase in perceived value as a percentage of project cost was greatest for simple designs with small evergreen plant material. Complicated designs that included hardscapes and large, diverse plant material returned the least. In general, we found that return on investment for landscaping is comparable to the returns gained on several major home improvements, yet differed with respect to geographic region. We found that colored hardscape, developed from a red brick paver walkway, returned less than color from flowering annuals. Return on investment was greatest for annual plants added for color.
526 Hawaiian Islands Horticulture: A Prehistoric Perspective
Authors: Bevacqua Robert F.
Published: February 2019

The introduction of horticulture to the Hawaiian Islands by Polynesian voyagers in AD 300 represents the culmination of eastward voyages of discovery by navigators whose origins were in southeastern Asia and who dispersed an important assemblage of horticultural crops through the Pacific islands. Archaeological, botanical, and linguistic evidence has been used to establish that these voyagers, using double-hulled sailing canoes, transported 27 horticultural plants with them in their voyage of discovery of the Hawaiian Islands. This assemblage included banana, coconut palm, sweetpotato, yam, breadfruit, and taro. The introduction of these plants had a dramatic and damaging impact on the island ecosystem. Many native species of plants and birds became extinct as the settlers used fire as a tool in clearing land for the planting of the introduced plants. A complex civilization developed based on the production of horticultural crops. The staple of food for this society was taro or kalo. The corm or underground portion was mashed with water and eaten as a paste called poi. Large, irrigated, terrace systems were developed for taro production. The most enduring achievement of the Polynesian navigators who explored and colonized the Hawaiian Islands was the dispersal of an assemblage of horticultural plants that transformed the natural environment of both Hawaii and much of the world's tropical regions.
532 Endogenous Gibberellins in Developing Apple Seeds in Relation to Biennial Bearing
Authors: Tu Yicheng , Hirst Peter , Coolbaugh Ronald , Pharis Richard
Published: February 2019

It is believed that gibberellins (GA) produced in apple seeds act as an inhibitory signal to flower induction in the neighboring buds. The alternate bearing behavior of an apple cultivar is therefore likely to be associated with the activity of endogenous GAs in the seeds of that cultivar. To elucidate the impact of GAs on the flowering of biennial and non-biennial apple cultivars, fruits were sampled from `Fuji' (biennial, on-year) and `Gala' (non-biennial) trees periodically during the early part of the growing season. Seeds were removed from fruits immediately, frozen in liquid Nitrogen and freeze dried. Full scan analysis for GAs using GC-MS identified 16 GAs: GA1, GA3, GA4, GA7, GA20, GA31, GA34, GA35, GA44, GA50, GA54, GA61, GA63, GA68, GA80, and GA88. In addition, we also traced a number of GA-like mass spectra that do not match any published GA mass spectrum reference. The possible structures of these GA-like compounds were also proposed. More types of GAs were found in `Fuji' seeds than in those of `Gala'. This suggests higher GA activity in `Fuji' considering almost all the GAs identified are biologically active. Unlike the results of recent researches on GAs in other apple cultivars, we found that the major GA types in both cultivars are GA80 and GA63, rather than GA4 and GA7. `Fuji' contained significant amounts of GA88, which did not appear in `Gala' samples. Other studies are currently underway to quantify specific GAs from these seeds using deuterated internal standards.
571 Undergraduate and Graduate Curriculum in Public Horticulture at The University of Tennessee
Authors: Hamilton Susan L. , Albrecht Mary L.
Published: February 2019

Students wanting to prepare for a career in public horticulture can now enroll in a new undergraduate and graduate curriculum at the Univ. of Tennessee. Beginning fall semester, 1999, students enrolled in the Dept. of Ornamental Horticulture and Landscape Design (OHLD) can opt to follow the new Public Horticulture concentration in the ornamental horticulture and landscape design major. The Public Horticulture concentration was the result of a year-long curriculum revision that reflects growth in career options in horticulture. The goal of the Public Horticulture concentration is to prepare students for careers that promote horticulture and emphasize people and their education and enjoyment of plants. Such careers include director of a botanical garden, arboretum, or park; city or urban horticulturist; extension agent, teacher, educational director, or program coordinator; professional garden writer/editor or publication manager; horticulture therapist; public garden curator; and plant collections manager. The Public Horticulture concentration allows students to take a breadth of ornamental horticulture courses, five of which are specific to public horticulture, along with supporting course work in soils, entomology, plant pathology, and botany, while providing the opportunity for students to take electives in education, extension, public administration, grant writing, museology, psychology, information sciences, journalism, and management. Students also complete an internship for graduation and have the opportunity to work in the Univ. of Tennessee Inst. of Agriculture Gardens.
582 Maintenance of Fruiting Potential through the Winter for Merlot Grapevines Grown in Southwestern Michigan
Authors: Zabadal Thomas J. , Dittmer Thomas
Published: February 2019

Producing the cold-tender wine grape Merlot is a major challenge in the cool-climate viticultural region of southwestern Michigan. Merlot grapes produced in this region provide a strong market opportunity; therefore, several strategies for preserving the fruiting potential of vines through the winter were evaluated over 5 years. Vines were managed with frequent trunk renewal so that they were pliable and capable of being laid near the ground. One treatment was (A) a control. Three treatments involved pruning vines in the late fall to two to four canes, which were then (B) laid on the ground without any cover, (C) attached to a wire near the ground and covered with straw, or (D) attached to a wire near the ground and covered with 20 cm of soil. The fifth treatment (E) involved arching unpruned vines to place canes near the ground but without any covering. Pruning was completed in spring, and vines were tied using fan training. Vines were adjusted to a maximum of 40 live nodes per vine. Winter minimum temperatures averaged 1, 8 and 16 °C warmer than the air temperature at 1.5 m above ground when measured at 0.3 m above ground (B and E), under the straw mulch (C), and under the soil (D), respectively. Very low ambient air temperatures of –27 and –28 °C were experienced in two of the winter periods. C, D, and E consistently provided greater node survival through the winter than control vines. B was inconsistent in performance. The lowest annual yields for A through E for the 5-year period were 3.1, 0.7, 8.3, 6.7, and 9.0 tons per hectare, respectively. These data indicate that treatments C, D, and E were capable of reliable annual production of Merlot grapes even in years with episodes of low winter temperatures. Projects are under way to develop commercial capability for the vine burial and mulching techniques used in this study.
592 Water Flux from Lettuce Plants at Reduced Atmospheric Pressure
Authors: Corey Kenneth A. , Fowler Phil A. , Wheeler Raymond M.
Published: February 2019

Reduced atmospheric pressures may be used to minimize mass and engineering requirements for plant growth habitats used in some extraterrestrial applications. A chamber with high vacuum capability and thermal control at Kennedy Space Center was used to measure water loss of lettuce plants at reduced atmospheric pressures. A test stand with three, high-pressure sodium vapor lamps was used to determine short-term plant responses to reduced pressure. Initial experiments with lettuce showed that a pressure of 10 kPa (≈0.1 atm) resulted in a 6.1-fold increase in the rate of water loss compared to water loss at ambient pressure. However, due to low relative humidity, plants wilted after 30 minutes exposure to 10 kPa. A follow-up experiment in which relative humidity was controlled between 70% and 85%, demonstrated that water loss was directly proportional to the vapor pressure gradient, regardless of atmospheric pressure in the pressure range of 10 to 101 kPa. However, the response was curvilinear, suggesting effects on the pathway resistance. Results indicate that plant growth at atmospheric pressures of 5 to 10 kPa should be achievable. Further work will necessitate better relative humidity control and carbon dioxide control in order to separate vapor pressure deficit effects from diffusion effects.
629 Influence of Plant Growth Regulator Chemicals, on the Growth and Development of Angelonia angustifolia `Blue Pacific', Asteriscus maritimus `Compact Gold Coin', and Heliotropium aborescens `Fragrant Delight'
Authors: Bartel Amy Lynn , Starman Terri W.
Published: February 2019

Angelonia angustifolia `Blue Pacific', Asteriscus maritimus `Compact Gold Coin', and Heliotropium aborescens `Fragrant Delight' are three vegetatively propagated species of annuals. The objective of this study was to find which plant growth regulator chemicals could be used to control height and produce compact, well-branched, flowering plants. The plants arrived as rooted plugs and were transplanted to 10-cm plastic containers. When the roots of the transplanted plugs reached the edge of their containers, 15 days after transplanting, the plant growth regulator chemicals were applied. Five different chemicals were used in spray applications at two rates measured in mg/L: ancymidol at 66 and 132; daminozide at 2500 and 5000; paclobutrazol at 20 and 40; ethephon at 500 and1000; and uniconazole at 10 and 20. One drench application of uniconazole at 1 and 2 mg/L and one control (water spray) were also used. Total plant height, plant width, flower number, node number, stem length, internode length, and numbers of days to visible bud were recorded. Ancymidol at both rates caused stunting and flower distortion in asteriscus; however, it was not effective on angelonia or heliotrope. Paclobutrazol and uniconazole sprays were ineffective in controlling height on all three species. Ethephon at both rates was effective in controlling height, and producing well-branched plants in all three species, yet it caused a delay in flowering. Uniconazole drench at both rates was also effective in controlling height but caused stunting. In general, daminozide at 5000 mg/L was most effective in controlling foliage height without a delay in flowering or decrease in flower size or number in all three species.
649 Post-production Fertility Management of New Guinea Impatiens Hanging Baskets
Authors: Zhang Donglin , Zuck Michael G.
Published: February 2019

To grow and sell fully charged hanging baskets to the customers is the future trend of retail markets. Impatiens ×hawkeri Bull. `Guadeloupe' (New Guinea Impatiens, Paradise KNG Series) was grown under liquid fertilizer culture until it reached marketable size on 4 June 1999. Then three different fertilizers (two slow-release and one organic) were applied at concentrations of 1.2, 2.4, and 3.6 g pure nitrogen and all hanging baskets were placed in four different family-owned nurseries. Overall performance, media pH, electrical conductivity (EC), and nutrients were measured every 3 weeks and tissue nutrients were analyzed every 6 weeks. New Guinea Impatiens requires low-fertility. Mature plants survived 3 months without extra fertilizer. The best performance was observed under the 3.6 g pure nitrogen treatment. Medium pH ranged from 6.0 to 7.5. No significant effect was observed among the different fertilizers and concentrations. EC increased in the first 6 weeks, then decreased to the beginning level at about 0.5 dS/m after 12 weeks under all fertilizer treatments. Compared with organic fertilizer, slow-release fertilizers had significantly lower EC, especially during the first 9 weeks. Macronutrients in media followed the same trend as EC, as did N and P levels in leaf tissues. K levels in leaf tissues decreased under all treatments and Ca and Mg levels showed an opposite trend compared with medium ones. The results indicate that both slow-release and organic fertilizers can be applied to charge New Guinea Impatiens hanging baskets for 3 months.
653 Achieving and Maintaining a Sustainable Agriculture
Authors: Harwood Richard R.
Published: February 2019

Our farm operations will face an array of challenges over the next decade that are increasing both in scope and intensity. Global markets, global supply, competition for water, land costs driven by the value of non-agricultural use, complexity of regulation, and consumer concern over what they perceive to be safe food are among the many challenges to farm enterprise sustainability. We will have to “contain” our soil, nutrients, crop and animal residues and production inputs within our field boundaries and in the upper layers of soil. We must do all of this while increasing productivity (achieving ever-higher nutrient and crop residue flow) and being cost-competitive. Many exciting advances are being made in engineering as well as in crop genetics. The most far-reaching, however, will be the contributions that will come from other parts of the biological revolution. The science of production ecology is helping us to better understand the myriad of biological and biogeochemical processes that we deal with daily. We are moving toward management of the genetics of pest populations. We will purposefully manage the diversity and amounts of crop residues in our fields which, in turn will control the populations of plants and animals in our soil. We will manipulate the incorporation and release of nutrients from organic fractions in our soil for containment and nutrient recycling. Our nutrient and chemical inputs will be targeted and largely supplemental rather than the direct mainstay of our production. If our production is to be a sustainable part of the landscape we must be seen to provide a high level and quality of hydrological and biodiversity services as part of our management of green space. The more advanced farms have pieces of this future in place now. Numerous examples will be presented from current research, focusing heavily on crop/soil interactions.
661 Molecular Biology of Host–Pathogen Interactions in Harvested Horticultural Crops
Authors: McCollum T.G.
Published: February 2019

Decay caused by fungal pathogens accounts for significant postharvest losses. Although the application of synthetic fungicides can reduce postharvest decay, increasing public concern over using fungicides as well as the resistance that develops to them indicate that alternative means of decay control are needed. Freedom from disease before harvest is the norm rather than the exception. Numerous defense mechanisms, both preformed and inducible, are involved in plant resistance to fungal pathogens. Understanding how natural defense mechanisms are regulated and how to maintain them in harvested products may provide the basis for new strategies to reduce postharvest losses caused by pathogens. Host–pathogen interactions have been well studied in growing plants but much less extensively in harvested organs. The interaction between host and pathogen is dynamic; changes in both organisms are required for disease development. Following harvest, the incidence of decay increases indicating that changes in the host render it more susceptible to pathogen development. Recent studies by plant physiologists and pathologists have contributed to our understanding of changes in harvested tissues that render them less resistant to decay as well as changes in the host that are induced in response to fungal infection.
669 Greenhouse Vegetable Production in China
Authors: Zheng Guanghua
Published: February 2019

There was a remarkable growth in China's greenhouse horticulture during the past decade. In 1989, the greenhouse area in China was 22,000 ha, but this figure reached up to 350,000 ha in 1999, about 16 times as large as that in 1989. Currently, the main greenhouse design used for commercial production is the energy conservation type—solar greenhouse—and many growers use eco-organic soilless culture for production. The substrates used for vegetable production are perlite, vermiculite, peat, coal cinder, sand, coir, sunflower stem, and sugar cane stem. Dry solid organic manure is mixed into the substrates before conducting cultivation, and then only water is for irrigation. Growing vegetables in this way improved quality, increased market value, and decreased environmental pollution.
673 A Synthesis of Worldwide Approaches for Rationalizing Nitrogen Fertilization of Vegetable Crops
Authors: Tremblay N. , Bélec C.
Published: February 2019

The necessity of achieving appropriate nitrogen fertilization of vegetable crops relates to both economical and environmental sustainability. Split nitrogen applications have been shown to improve N-use efficiency, in line with the aforementioned objective and should therefore be encouraged. Given the variation in the amount of N naturally provided to, or uptaken by, the crop, strategies are required to tailor supplementary fertilization to actual crop needs, keeping in mind the absolute requirement for optimal yield in quality and quantity. It is suggested that the fertilization rates applied at sowing or later in the season can be figured in two manners. The first relies on modelling; the second on measurements. The modelling (N budget) approach, mostly linked to initiatives on the European continent, would be most applicable to the determination of the first fertilizer dressing. When a plant stand is established, however, canopy-based measurements made either directly or remotely could be developed to make use of the capability of the plants to integrate the properties of the soil environment and to decide upon further top-dressed applications. For this purpose, a fully fertilized “reference plot” has to be introduced in the field in order to overcome the variability induced by season, site and cultivar. With the emergence of “precision farming” and “remote sensing technologies” it is now possible to adjust fertilizer inputs not only at the field level but also within fields based on actual, localized requirements.
689 Field Research and Development of Plant Growth Regulators by the Agrochemical Industry
Authors: Campbell Craig A.
Published: February 2019

The purpose of this presentation is to describe the general Field R&D process undertaken by Abbott Laboratories and other agrochemical companies when developing a new plant growth regulator (PGR). A recently registered PGR for citrus named `EcoLyst' is used throughout the presentation as an example of common development strategies. Agrochemical companies acquire many new PGR compounds from outside sources, while others are discovered internally. Internal technology is obviously much simpler to control. In Abbott's case, most of the new PGR compounds are brought in from other places as a result of focused efforts to find new technology for development. Researchers, sales and marketing personnel, and full-time acquisition specialists all share the responsibility for finding new prospect PGRs. After a new PGR is identified, a company like Abbott must first determine if the lead is potentially available, and then, if it has sufficient value to warrant acquisition or in-licensing efforts. Once a PGR passes an initial screening process and is approved for potential development, a coordinated chain of events is initiated throughout the company's organization to accelerate work on the project. Field R&D creates a comprehensive research plan for the PGR that contains development goals. The scope of the research program increases significantly after the first research year, provided results are favorable. University and government scientists are generally brought into the research programs after a year or two of in-house testing. At predetermined control points in the development process, go/no go decisions are made based on reviews of research data, business plans, and regulatory progress.
696 Asian Horticultural Crops and Human Dietetics
Authors: Palaniswamy Usha
Published: February 2019

Great mass of epidemiological evidence linking better health and lower risk of major diseases and chronic conditions such as heart disease and cancer to Asian dietary practices have stimulated interest in the Asian food crops. Another reason why Asian crops are gaining popularity is the dramatic growth in the Asian American population in North America, increasing more than 20% in the United States in the 1990s. The Asian populations are also increasing in diversity by the growing numbers of Indians, Thais, Vietnamese, and Cambodians, who are adding up to the more-established Asian Americans of Chinese, Japanese, and Korean origin. In addition to the diverse “fresh” vegetarian cuisine, the Asian medical systems that predominantly use herbs have fueled an interest in “foods used as medicine” and have acclaimed popularity among the general public.
Optimal Training of Apple Trees for High-density Plantings
Authors: Brown Gerald R. , Wolfe Dwight E.
Published: February 2019

An experiment was initiated at the Univ. of Kentucky Research and Education orchard, Princeton, Ky., to determine the training practices needed to obtain early production and optimal fruit size from trees trained to either the slender spindle or the French axe system on vigorous sites. One-hundred-eighty trees (five rows, 32 trees per row) of `Golden Delicious' on M.9 rootstock were planted in May 1997, in a randomized complete-block design with eight treatment combinations, consisting of two training systems and four levels of training intensity. Trunk circumference averaged 61 cm at planting and did not vary significantly among rootstocks. A trellis was constructed, and trickle irrigation was installed. All trees are currently alive. Each season, over half the total time spent training the trees was spent during the first 5 weeks the trees were trained. About 2 minutes per week was needed to train each tree during the first 5 weeks, but only 45 seconds per week was needed in the sixth through the 16th week. Trunk circumference, yield, and average weight per fruit did not vary significantly in the analysis of variance. Training per kilogram of fruit averaged 4.2 minutes.
The Georgia Advanced Master Gardener Training
Authors: Westerfield Robert
Published: February 2019

Georgia has about 6000 Master Gardeners in the state. Although the initial training received by these volunteers was excellent, there was a need for more in-depth, updated, specialty training. Advanced Master Gardener Training was developed to provide a higher level of educational training to veteran Master Gardeners. Thirteen specialty topics were developed to enhance volunteer knowledge in areas such as envionmental horticulture, turf grass, or xeriscape. Over 600 Master Gardeners have now gone through advanced training and have been certified. Pre- and post-testing has shown a significant increase in knowledge gained at these trainings. Master Gardeners are required to attend five specialty trainings and pass the post-test before they are certified as “Advanced Master Gardeners.” In return for the training, Master Gardeners are required to serve as resources in the topics of the programs they attend. They may be asked to write news articles, teach programs, or assist with future advanced training. A “second level” advanced training is being planned for 2001 with a stronger emphasis on water quality and envionmental horticulture.
Firmness of `Brightwell' Rabbiteye Blueberry in Response to Various Harvesting and Handling Procedures
Authors: NeSmith D. Scott , Prussia Stanley E. , Krewer Gerard
Published: February 2019

Experiments were conducted during 1999 at the Univ. of Georgia Research Farm near Alapaha with the rabbiteye blueberry (Vaccinium ashei Reade) cultivar Brightwell to determine how various harvesting and handling tactics influenced firmness. The research was facilitated by availability of a mechanical harvester and a commercial packing line. Firmness was determined with a FirmTech II firmness tester on fruit samples before and after cold storage. Fruit harvesting methods included machine harvesting in bulk, hand harvesting in bulk, and hand harvesting directly into clam shell containers. Assessment of precooling effects were made by comparing firmness of fruit that were placed immediately over ice after harvest to fruit that remained at ambient temperatures for 24 hours after harvest. Additional measurements were made to discern the effects of grading and sorting on fruit firmness. The data overall indicated that `Brightwell' fruit firmness was “acceptable” regardless of the harvesting and handling methods experienced. However, there were considerable firmness losses caused by the various procedures. The greatest loss in fruit firmness (20% to 25%) was caused by machine harvesting. This was followed by a 15% to 18% loss of firmness due to grading and sorting. Immediate cooling of fruit after harvest resulted in only a 8% to 12% increase in firmness as compared to keeping fruit at ambient temperature for 24 hours. These findings should be useful to growers and packers in targeting segments of their operations that can be manipulated to improve berry firmness and quality for fresh market sales.
Changes in Antioxidant Activity in Developing and Ripening Strawberry Fruit
Authors: Woods F.M. , Mosjidis C. , Hilmerick D. , Ebel R.C , Wilkins B.
Published: February 2019

Strawberry fruit (Fragaria ×ananassa `Chandler') were evaluated at five different stages of growth and development for changes in the senescence process in fruit tissues. Levels of total antioxidant activity, hydrogen peroxide (H2O2), lipid peroxidation product, malondialdehyde, and ethylene production were determined. Total antioxidant activity (TAA) was measured in terms of in situ antioxidants to scavenge the ABTS.superscript +superscript radical cation. With the progression of ripening and senescence, there was a significant decline in TAA that coincided with increased concentration of H2O2, lipid peroxidation and increased production of ethylene. Our results illustrate that the senescence process in strawberry fruit is associated with the decline of TAA and the potential initiation and accumulation of reactive oxygen species. These results are additionally discussed in terms of potential processes associated with abiotic and biotic environmental stresses. Moreover, although strawberry fruit are typically classified as nonclimacteric, this study illustrates that the free radical mediated senescence process is similar to that of climacteric fruits.