bluuebunny/crossref_metadata_2025 huggingface dataset:
354 Influence of Foliar Application of Calcium Nitrate on Carrot Root Tissue Electrolyte Leakage and Storage Characteristics
Authors: Lee Chiwon W. , Cho Keun Ho , Cihacek Larry J. , Stack Robert W.
Published: February 2019

The influence of calcium nitrate fertilization on the storage characteristics of carrot (Daucus carota) roots was investigated. Plants of `Navajo' carrots grown under irrigation were sprayed with a 2% solution of Ca(NO3)2 4H2O at a rate of 50 kg/ha Ca 10 days before harvest. Quality of carrot roots stored at 5 °C was evaluated monthly for sweetness, tissue electrolyte leakage, disease development and visual characteristics. For disease development, the crown portion of the carrot roots was inoculated with an ascospore solution (2 × 109 spores/mL) of white mold (Sclerotinia sclerotiorum) before storage. When determined after 1 month of storage, percent tissue electrolyte leakage in the Ca-treated carrots decreased 52% as compared to that obtained from the control. Sugar contents of the cortex and xylem tissues were not affected by calcium nitrate fertilization. Changes in other quality parameters of carrot roots for an extended storage period, including white mold development, will be presented. Initial findings of this research suggest that foliar calcium feeding at the final stage of plant growth may enhance the quality of carrot roots during storage.
355 Effect of Season on Nitrate Accumulation in Hydroponic Lettuce
Authors: Gent Martin P.N.
Published: February 2019

Serial plantings of hydroponic lettuce were grown throughout the year in the northeast United States to determine how sunlight intensity and solution nitrate affect nitrate in leaf tissue. Two nutrient solutions were used. All essential elements were supplied at the same concentration, except nitric acid was added to the high-N treatment to increase nitrate to 5.7 mm (352 ppm), compared to 4.0 mm (248 ppm) in the low-N treatment. A feedback control system maintained a constant conductivity and volume in the recirculating nutrient solution. The actual nitrate concentration in solution was higher in winter than in summer. In winter, it rose to 800 ppm in the high-N solution, while it remained below 200 ppm in the low-N solution. In summer, nitrate was 200 to 400 ppm in the high-N solution, compared to 40 to 120 ppm in the low-N solution. Concentration of other mineral elements remained at levels similar to the original formulation. Nitrate concentration in leaf tissue when the lettuce plants reached a marketable size was sensitive to sunlight and nitrate supply. In spring and summer, tissue nitrate was as low as 1100 ppm. It increased to about 4000 ppm in lettuce grown in mid-winter in a shaded greenhouse and fed high-N solution, while low-N plants had less than 3000 ppm nitrate. Tissue nitrate was related to solution nitrate. Tissue nitrate increased in proportion to solution nitrate, up to about 400 ppm nitrate in solution, then leveled off at a concentration of about 4000 ppm in the leaves, a relation that was the same under all sunlight intensities. The accumulation of nitrate in the nutrient solution was one cause of the high concentration of nitrate in lettuce leaves.
361 Effects of Fertilizer Rates on Fruit Quality of `White Marsh' Grapefruit in a Sandy Soil
Authors: He Z.L. , Calvert D.V. , Alva A.K. , Li Y.C.
Published: February 2019

Fertilization is among the most important factors influencing fruit quality of citrus. Effects of Individual element such as N, P, or K on fruit quality have been well-documented. Much less has been done on the interactions of N, P, and K in relation to citrus fruit quality. A field experiment was conducted from 1994 to 1999 in a commercial grove on a Riviera fine sand (Loamy, siliceous, hyperthermic Arenic Glossaqualf) to investigate the effects of fertilizer rates and sources on fruit quality of 26-year-old `White Marsh' grapefruit trees (Citrus paradisi Macfad.) on Sour Orange rootstock (Citrus aurantium Lush). Fertilizer was applied as water-soluble dry granular broadcast (three applications/year) at N rates of 0, 56, 112, 168, 224, and 336 kg/ha per year using a N;P:K blend (1.0:0.17:1.0). There was a quadratic relationship between fruit weight or peel thickness and fertilizer rates. Fruit weight per piece increased with fertilizer rates from 0 to 168 kg N/ha per year, but decreased from 168 to 336 kg N/ha per year. Fruit size was small at zero or low fertilizer rates due to nutrient deficiencies. Large fruit sizes of `White Marsh' grapefruit in the sandy soil were achieved at fertilizer rate around 168 kg N/ha per year. Increasing fertilizer application rates higher than 168 kg/ha per year greatly increased the number of fruit per tree, but decreased the size of fruit. Peel thickness, which is related to the fruit size, declines at higher fertilizer rates. Increase in fertilizer rate from 0 to 336 kg N/ha per year increased solids content and fruit acid concentration of the grapefruit. Fertilization rate effect on fruit Brix concentration was more complicated. Brix concentration was not affected by increasing fertilizer rates from 0 to 168 kg N/ha-per year, but was increased at higher fertilization rates (168 to 336 kg N/ha per year). As a result, the Brix/acid ratio was, in general, decreased by increasing fertilizer rates.
363 Near-infrared Reflectance Spectroscopy for the Determination of Total Nitrogen, Amino Acid, and Nonstructural Carbohydrates in Apple and Almond Samples
Authors: Ding Pinghai , Dong Shufu , Cheng Lailiang , Bi Guihong , Fuchigami Leslie H.
Published: February 2019

Near-infrared (NIR) reflectance spectroscopy was used to determine the chemical composition of fruit and nut trees. Potted almond and bench-grafted Fuji/M26 trees were fertigated during the growing season with different N levels by modifying the Hoagland to create different levels of nitrogen and carbohydrates in plant tissues during dormancy. Dried, ground, and sieved shoot, shank, and root samples were uniformly packed into NIR cells and scanned with a Foss NIRSystem 6500 monochromator from 400 to 2500 nm. Statistical and multiple linear regression methods were used to derive a standard error of performance and the correlation between NIR reading and standard chemical composition analysis (anthrone, Kjedahl and Ninhydrin methods for carbohydrate, total N, and amino acid analysis, respectively) were determined. The multiple determination coefficients (R2) of apple and almond tissues were 0.9949 and 0.9842 for total nitrogen, 0.9971 and 0.9802 for amino acid, and 0.8889 and 0.8687 for nonstructural carbohydrate, respectively.
364 Studies on the Effects of Nitrogen Source on Pecan Nutrient Uptake and Plant Growth and Development
Authors: Kim Tehryung , Mills Harry A. , Wetzstein Hazel Y.
Published: February 2019

As a plant nutrient, nitrogen is the element in highest demand in terms of quantity and makes up about 2% to 3% of plant dry matter. In this study, we evaluated the effect of nitrogen source on plant growth and nutrient uptake in pecan (Carya illinoensis). Seedlings were hydroponically grown under three nitrogen nutrient regimes where the ratio of nitrate: ammonium was varied, i.e., 3:1, 1:1, and 1:3. High ammonium nutrition had an inhibiting effect on seedling growth. Plants grown under 1:3 (nitrate: ammonium) exhibited significantly lower biomass, decreased root/shoot ratio, and lower specific leaf weight than other treatments. Total nitrogen uptake on a dry weight basis was highest in the high ammonium treatment. In the equal molar treatment (1:1 nitrate: ammonium), plants exhibited preferential uptake of ammonium-form nitrogen. Ammonium-form nitrogen is generally used in pecan orchard practice. Our data suggest that further studies evaluating the effects of nitrogen source are warranted to determine if similar detrimental effects on pecan growth occur in the field. Such studies would be useful for optimizing current fertilization practices.
365 Seasonal Fluctuations in Nutrients and Resorption Efficiencies of Different Pecan Genotypes
Authors: Kim Tehryung , Wetzstein Hazel Y.
Published: February 2019

It has been shown that perennial woody plants exhibit marked seasonal changes in nutrient content, carbon metabolism, and organ development. A knowledge of seasonal nutrient allocation and temporal accumulation patterns can be useful in the development of fertilization regimes that reflect the biology of a tree crop. Maintenance of optimum leaf nutrient status is an important priority in pecan cultural practice. However, a systematic evaluation of nutrient resorption is lacking in pecan. In this work, seasonal changes in nutrients and carbohydrates were evaluated in pecan trees grown under orchard conditions. In addition, resorption efficiencies of eight pecan cultivars were evaluated. Significant levels of resorption were observed in all essential elements, but cultivar differences were not significant. Seasonal patterns of nutrient and carbohydrate content in leaf, stem, and shoot tissue, will be presented as well as a structural evaluation of abscission zone formation.
368 Effects of Nitrogen Fertilization on Saw Palmetto (Serenoa repens)
Authors: Carrington Mary E. , Ozores-Hampton Monica , Mullahey J. Jeffrey
Published: February 2019

Saw palmetto (Serenoa repens), a palm species native to the Southeastern United States, is used in ornamental plantings and landscaping. From Mar. 1998 to Mar. 1999, we conducted an experiment to assess effects of different levels of nitrogen addition on three sizes of containerized saw palmettos in southwest Florida. Palmettos were in 26-L containers (plant height 30 to 50 cm, no above-ground rhizome), 38-L containers (plant height 50 to 80 cm, above-ground, prostrate rhizome), and 170-L containers (three erect above-ground rhizomes 1 to 2 m high). We applied granulated ammonium nitrate (34% N) to the soil surface four times during the year, at 6 yearly rates of N addition for each size category of palmettos (24 palmettos in each size category). We also applied granulated concentrated triple superphosphate (46% P2O5) and potassium chloride (60% K2O) at constant yearly rates for each size category. We measured height and width of plants and length and width of leaves at the beginning and end of the experiment. We quantified leaf N, P and K concentration two days after first fertilizer application, and at the end of the experiment. For 26-L plants, increasing rates of N addition were reflected in higher levels of leaf N concentration two days after the first application. Leaf growth was less, and leaf K concentration at the end of the experiment was lower with increasing rates of N addition. Leaf P concentration at the end of the experiment decreased, and then increased with increasing rates of N addition. Plant growth for 170-L plants decreased and then increased, and leaf P concentration at the end of the experiment decreased with increasing rates of N addition.
370 Iron and Iron Compounds Reduce Phosphorus Leaching from Nursery Containers
Authors: Gillman Jeffrey H. , Rosen Carl J.
Published: February 2019

Phosphorus contamination of surface water is a growing problem associated with container production of nursery plants. Iron and iron compounds have the ability to adsorb phosphorus and render it immobile. Incorporating iron compounds into media at the base of nursery containers serves to filter out phosphorus from fertilizers while still allowing the plant to collect enough phosphorus to grow. Two experiments were devised. The first experiment examined how much phosphorus various iron compounds would adsorb. Metallic iron adsorbed the most phosphorus, followed by HCl reacted magnetite (a form of iron ore), Fe2O3, Fe3O4 and magnetite. In the second experiment, PVC tubes (4 cm inner diam.) were filled to a level of 5 cm with a phosphorus adsorbing layer containing growing media that was 25% or 50% by weight iron compounds. Compounds included metallic iron, HCl reacted magnetite and magnetite. Plain media was used as a control. A layer of 15 cm of media and slow-release fertilizer was applied above the adsorptive layer. One hundred milliliters of distilled water was applied to PVC tubes daily to simulate irrigation. Metallic iron reduced phosphorus leachate to almost 0 for over 2 weeks. HCl reacted magnetite was also effective in reducing phosphorus leachate. Magnetite only affected phosphorus leachate slightly.
371 Influence of Inorganic and Organically Based Fertilizers on Plant Growth and Nutrient Leaching
Authors: Altland James E. , Gilliam Charles H. , Edwards James H. , Keever Gary J.
Published: February 2019

Selected fertilizer treatments were applied to vinca (Catharanthus roseus `Peppermint Cooler') in the landscape to determine their effect on growth and nutrient leaching. In plots 0.9 m × 2.3 m, inorganic fertilizers were applied as either a single application of 4.9 g N/m2 pre-plant, or a split application with 4.9 g N/m2 applied pre-plant followed by application of 2.45 g N/m2 at 8 and 12 weeks after planting (WAP). Inorganic fertilizers included 15N–0P–12.6K granular fertilizer, Osmocote 14N–6.0P–11.6K, and Osmocote 17N–3.0P–10.1K controlled-release fertilizers. Three different organically based fertilizers were applied pre-plant and were composed of recycled newspaper amended with animal manures (chicken, beef cattle, or dairy) and adjusted with (NH4)2SO4 to achieve C:N ratios of either 20:1 or 30:1. A standard industry treatment of 13N–5.6P–10.9K (4.9 g N/m2) incorporated pre-plant and 17N–3.0P–10.1K (4.9 g N/m2) topdressed post-plant was also included. Leachates, collected with lysimeters, from inorganic fertilizer plots had lower levels of total N (NO3– + NH4+) compared to organically based fertilizer plots through 8 WAP. Of the inorganic fertilizer plots, those receiving 15N–0P–12.6K granular fertilizer had higher total N levels at 1, 2, and 4 WAP than other inorganic fertilizer plots. Total N in leachates declined over the study and by 12 WAP were similar among all treatments. Vinca treated with organically based fertilizers (C:N 20:1) had the highest foliar color ratings through 8 WAP; however, color ratings declined thereafter and by 16 WAP had the lowest ratings. Plants treated with organically based fertilizers had greater shoot dry weights 20 WAP and larger growth indices 8 and 20 WAP.
372 Nitrogen and Phosphorus Release from Controlled-release Fertilizers while Overwintering Nursery Stock under Plastic
Authors: Ristvey Andrew , Lea-Cox John
Published: February 2019

Nutrient release patterns from several different controlled-release fertilizers (CRF) were studied during the overwintering period of a long-term nutrient uptake, leaching, and loss study of Azalea (Rhododendron) cv. `Karen' and Holly (Ilex cornuta) cv. `China Girl', under sprinkler and drip irrigation. In Maryland, diurnal winter temperatures can vary from ≈10 °C to above 15 °C. Most growers, therefore, cover frames with opaque plastic for cold protection from November through April. This is also the period when many growers apply CRFs on those plant species that take more than 1 year to produce. Few data are presently available on the release patterns of CRFs under variable temperature conditions in late winter/early spring. We hypothesized that substrate temperatures warmer than 15–16 °C will result in CRFs releasing nutrients at a time when root systems are inactive, with a major loss of nutrients with the first few irrigations in Spring. This 105-day study quantified nitrogen (N) and phosphorus release patterns from four brands of CRF (Osmocote, Nutricote, Scotts High N, and Polyon) with 270- and 360-day release rates, under these conditions. Each CRF was top dressed onto blocks of 18-month-old holly or azalea (n = 112) in 11.5-L (3-gal) containers, at a (low) rate of 6.1 g N per container. Ten randomly selected pots from each treatment were sampled every 15 days using two sequential leachings of distilled water, for a target leaching fraction of 25%. Leachates were recovered and analyzed for nitrate and orthophosphate concentrations. Ambient canopy temperatures were recorded continuously with remote temperature (HoBo) sensors from which degree days above 15–16 °C were calculated and correlated with CRF release patterns.
377 Differential Response of Two Poinsettia Cultivars to Calcium Stress for Postharvest Disorders
Authors: Bible Bernard , McAvoy Richard
Published: February 2019

Poinsettia (Euphorbia pulcherrima Willd. ex Klotzch) bracts are susceptible to postharvest disorders like the pathogen Botrytis cinerea and the abiotic disorder bract necrosis that degrade plant appearance. `Freedom Red' and `Supjibi' poinsettias were grown hydroponically with Ca concentrations of 0.5 or 4 mm. Forty days after initial anthesis, plants were harvested and their bracts subdivided into true-bracts and transitional-bracts for determination of incidence of botrytis lesions and bract necrosis. Mineral nutrients in bract margins were determined only for true-bracts. Margin Ca concentrations were relatively high in true bracts only for `Supjibi' plants exposed to 4 mm Ca solutions. Botrytis incidence was increased for transitional-bracts but not true-bracts for both cultivars by plant exposure to low (0.5 mm) Ca solutions compared to control (4 mm Ca) plants. The smaller the poinsettia roots relative to shoots, the higher the incidence of botrytis for `Freedom Red' transitional-bracts and `Supjibi' true-bracts. Botrytis incidence was higher on transitional-bracts (13%) than on true-bracts (3.5%) for both cultivars exposed to low Ca, whereas the incidence of bract necrosis on `Supjibi' was the same on true-bracts and transitional-bracts in either Ca solution. Bract necrosis was not evident on `Freedom Red' plants in either the 0.5 or 4-mmmm Ca solutions, however for `Supjibi' exposure to low Ca solutions increased incidence of bract necrosis from 5.5% for controls to 19.3%. The effect of Ca stress applied to poinsettia roots was genotype dependant for bract necrosis but not for botrytis.
378 Calcium–Boron Regimes Effect Incidence of Postharvest Disorders on Poinsettia Bracts
Authors: Bible Bernard , McAvoy Richard
Published: February 2019

Incidences of poinsettia (Euphorbia pulcherrima Willd. ex Klotzch) bract disorders like the pathogen Botrytis cinerea and the abiotic disorder bract necrosis are related to nutrient stress. `Supjibi' poinsettias were grown hydroponically with four Ca-B combinations of 0 or 4 mm Ca added with either 5 or 120 μmol B added. Forty-one days after initial anthesis, plants were harvested and their bracts subdivided into true-bracts and transitional-bracts for determination of incidence of botrytis lesions and bract necrosis. Mineral nutrients in bract margins were determined for leaves, transitional-bracts and true-bracts. Leaf margins had the highest concentrations of Ca and B. Margins of transitional-bracts had substantially lower concentrations and margins of true-bracts the least. The low Ca (0 mm) or low B (5 μmol) treatments greatly reduced the concentrations of these elements, respectively, in all three tissue types. The low Ca-low B treatment increased the incidence of bract necrosis on true-bracts from 1.9% on controls (4 mm Ca, 120 μmol B) to 27%. Low Ca treatment increased bract necrosis on transitional-bracts from 1.6% on controls to 24.3%. Bract necrosis incidence was the same on true-bracts and transitional-bracts, whereas the incidence of botrytis was higher on transitional-bracts than on true-bracts. Botrytis incidence was increased for true-bracts and transitional-bracts by plant exposure to low Ca solutions compared to plants in 4 mm Ca. Low Ca reduced growth in roots, but not shoots. Ca and B stress to roots increased the incidence of bract necrosis on true-bracts, while only Ca stress increased incidence of botrytis.
381 Food Safety Starts on the Farm: A Comprehensive Food Safety Curriculum for Fruit and Vegetable Extension Agents
Authors: Gravani Robert B. , Rangarajan Anusuya , Bihn Elizabeth
Published: February 2019

The 1998 Fresh Trends Survey, conducted by “The Packer,” indicated that about 60% of consumers are more concerned today, than 1 year ago, about Salmonella, E. coli 0157:H7, and other bacteria on fresh produce. Since 1987, the number of produce-associated outbreaks has doubled, affecting twice as many people, and involving a variety of fruits and vegetables. Three quarters of these outbreaks (75%) were associated with domestically grown produce. In recent months, as several large grocery chains have informed their produce suppliers that growers must have a certified plan for the farm that focuses on reducing risks for microbial contamination, to continue supplying fruits and vegetables. These actions have caused extreme concern among fruit and vegetable producers. A comprehensive educational curriculum has been developed for growers and shippers focused on recommended “Good Agricultural Practices.” This effort is the result of an extensive collaborative project, involving researchers, extension educators, and grower organizations nationwide. The curriculum sections include the history of foodborne illness associated with produce, the basic principles of food microbiology, recommended good agricultural practices to reduce risks of contamination due to irrigation water, wild and domestic animals, manure, and farm workers hygiene, resources for training employees, farm assessment worksheets, and other information resources. These educational materials and visuals will be made available on CD-ROM in the near future.
383 Landscape Professionals Learn Environmental Practices through the FYN/CLIP Program
Authors: Knox Gary W. , Burkey Fred , Kelly-Begazo Christine
Published: February 2019

The Florida Yards & Neighborhoods Program (FYN) provides special educational and outreach activities directed at the community to help Floridians reduce pollution and enhance their environment by improving landscape management. The Commercial Landscape Industry Professionals program (CLIP) was developed to provide training in FYN principles to Florida's landscape professionals. CLIP was pilot-tested from 1997 to 1999 in the six-county Indian River Lagoon area of coastal east-central Florida. Teaching resources, audiovisuals, teaching outlines, and reference materials were developed to create an FYN/CLIP curriculum, which was delivered to landscape maintenance personnel through a series of training programs. In addition, the pilot program developed marketing approaches, incentives, and recognition programs for landscape professionals to encourage their participation in CLIP training programs. Evaluations of training programs and results of pre- and post-test questionnaires demonstrate the effectiveness of the FYN/CLIP program.
400 Pepper Growth and Productivity Response under Various Certified Organic Soil Treatments
Authors: Delate Kathleen , Lawson Vincent
Published: February 2019

Organic farming has increased to a $6 billion industry in the U.S. and continues to expand 20% annually. In Iowa, organic acreage for all crops has increased from 13,000 in 1995 to 130,000 in 1999. Most organic farmers rely on crop rotations, compost, or manure applications, and cover crops to maintain soil fertility. In our trials at the Iowa State Univ. Muscatine Island Research Farm, a cover crop of hairy vetch (Vicia villosa) and rye was seeded in the fall and incorporated 2 weeks prior to transplanting `Lantern' pepper plants. Other organic and conventional soil treatments were applied at transplanting and at 3 weeks post-planting. Four replications of 40 peppers transplanted at 31 × 61-cm spacing under seven fertilization treatments were observed for plant growth and yields. The fertilization goal was to obtain equivalent nitrogen and calcium rates in the organic and conventional systems. Plants fertilized with the compost at 88 kg/ha N plus BioCal® (a liming industry by-product) were not significantly greater in leaf biomass than plants conventionally fertilized with equal amounts of N. All organic and conventional treatments had greater biomass and yield than the organic and conventional controls (no fertilizer), respectively (P = 0.05). Pepper fresh weight was greater in the vetch-strips treatment than in the vetch-incorporated, and the 44 kg/ha N compost treatment, but significantly less than the conventionally fertilized plants. Second year results demonstrated similar results to the 1998 trial where the greatest yields in the organic system occurred in the compost at 88 kg/ha N plus BioCal® treatment, demonstrating to organic farmers that comparable yields can be obtained in systems employing alternatives to synthetic nitrogen fertilizer.
420 Creating a Synchronous Course between Universities Using Distance Technologies
Authors: Williams Kimberly A. , Paparozzi Ellen T.
Published: February 2019

A model for the creation of shared synchronous courses between universities has been developed based on our experiences during the development and delivery of an upper-level undergraduate/graduate course in Plant Nutrition and Nutrient Management offered by Kansas State Univ. and the Univ. of Nebraska–Lincoln. The course was conducted during the Spring 1999 semester using two-way compressed video so that instructors and students at both sites could see and hear each other in live time. Our model is set up as a flow-chart and currently has 10 steps that include areas such as “Identifying the Need,” “University Must-Do's,” “Distance Class Technology Requirements,” and “Advertising the Course.” Each step details procedures to follow, offers ideas and suggestions, and includes examples taken from our course. Also included is information about web site development and chat room use. The model is easily adapted for use with distance technologies similar to two-way compressed video such as Internet 2. An electronic version of the model can be accessed at http://www.oznet.ksu.edu/dp_hfrr/Floriculture.
430 Ecotype Affects Growth and Flowering of Rudbeckia hirta L.
Authors: Norcini Jeffrey G. , Thetford Mack , Moore Kimberly A. , Bell Michelle L. , Harbaugh Brent K. , Aldrich James H.
Published: February 2019

Evidence is presented that native populations of Rudbeckia hirta L. (Blackeyed Susan) may be adapted to regional conditions. Two Florida ecotypes, one from north Florida (NFL) and one from central Florida (CFL), were better able to withstand the low fertility sites under three AHS Heat Zones (9, 10, 11) in Florida than were plants grown from Texas (TEX) seeds. Plants from TEX seed were the largest and showiest (generally the greatest number of flowers; largest flowers) but the shortest-lived. Most of these plants did not survive beyond August (about 6 months after transplanting) regardless of site. The CFL plants were especially tolerant of flooding conditions at Ft. Lauderdale. Under garden conditions, CFL Black-eyed Susan may be a highly desirable wildflower for subtropical or tropical summers.
436 1-Methylcyclopropene and Waxing Regulate the Ripening Storage Life of Avocado Fruit
Authors: Jeong Jiwon , Huber Donald J. , Sargent Steven A.
Published: February 2019

1-Methylcyclopropene (1-MCP), an inhibitor of ethylene action, has been shown to extend the storage life of avocado fruit. Waxing is also known to extend the storage life of avocado by reducing water loss and modifying the fruit internal atmosphere. In this study, 1-MCP and waxing were used to investigate their effects on ripening characteristics in avocado fruit. Preclimacteric `Tower II' and `Booth 7' avocados were treated with 1-MCP (Ethylbloc®) for 12 h at 20 °C. Half of the fruit were waxed (Sta-Fresh 819F®, FMC Co.) after 1-MCP treatment. The fruit were subsequently stored at 13 °C or 20 °C at 85% RH. As evaluated by fruit firmness, ethylene evolution, and respiration rate, 1-MCP and waxing delayed the ripening of `Tower II' avocados stored at 20 °C. Fruit treated with both 1-MCP and wax had better retention of green peel color and fruit firmness, and the delayed climacteric pattern of ethylene evolution and respiration rates. Waxing reduced weight loss and retarded softening, but did not delay climacteric ethylene evolution and respiration rates. Whereas firmness of control fruit decreased from >100 N to 20 N in as few as 7 days at 20 °C, fruit treated with both 1-MCP and wax reached 20 N over 11 days at 20 °C. The firmness of `Booth 7' avocados treated with both 1-MCP and wax decreased from >170 N to 20 N over a 5-week period at 13 °C. Current studies are addressing the nature of the dramatic decrease in firmness of MCP-treated fruit.
437 Development of Safe Working Atmospheres for Enhanced Storage of Horticultural Crops
Authors: Mir N.A. , Beaudry R.M.
Published: February 2019

O2 and C2H4 are biologically active molecules of importance in plant metabolism and their availability is manipulated to modify plant behavior during storage and the shelf-life period of harvested plant products. Respiratory curves describing the dependence of O2 uptake on O2 were obtained for slicing and `Roma'-type tomato, and `Jonathan' and `Empire' apple fruit at 20 °C for ripening fruit and for mature, non-ripening fruit. Mature, non-ripening fruit were maintained in that state by the application of 1-methylcyclopropene (1-MCP) or the use of a nonripening mutant in the case of tomato. The range of O2 atmospheres wherein the reduction of O2 relative to ambient yielded a significant (50%) reduction in respiration relative to the maximal rate of respiration, but was above the fermentation threshold, was termed the `safe working atmosphere' (SWA). For apple, there was no SWA for non-ripening apple fruits since a 50% reduction in respiration occurred at the fermentation threshold. During ripening, the respiratory curve shifted, revealing a marked increase in the apparent Km and maximal rate of respiration with no change in the fermentation threshold, resulting in the creation of a SWA of 6.5 kPa O2. A similar, less dramatic, shift in the respiratory curve for tomato fruit also occurred. In a flow-through system, low O2 reduced the rate of respiration of ethylene insensitive tomato fruit by ≈50% and resulted in an approximate doubling of the storability of the fruit. Insensitivity to ethylene yielded fruit with a respiratory rate approximately one-half that of ripening fruit, but storability was improved about 5-fold. The data collectively suggest that inhibition of ripening, rather than global metabolism via reduced respiration is key to preserving fruit quality.
438 Use of 1-MCP to Reduce the Requirement for Refrigeration and Modifed Atmospheres in the Storage of Apple Fruit
Authors: Beaudry R.M. , Mir N.A.
Published: February 2019

The growth regulator 1-methylcyclopropene (1-MCP) is a vapor under physiological conditions and acts by inhibiting the binding of the hormone ethylene to its binding site and a single exposure can temporarily render plant material insensitive to ethylene when applied at the parts-per-billion level. Apple fruit were harvested 1 week prior to the climacteric (harvest 1), at the onset of the climacteric (harvest 2), and 1 week after the onset of the climacteric (harvest 3). Fruit were stored at 0, 5, 10, 15, and 20 °C and were given treatments with 1 ppm 1-MCP on a once-per-week, once-per-2 weeks, once-per-month, and once-per-year basis or were left untreated. In terms of reduced softening, earlier harvested fruit were more responsive to the 1-MCP treatment and the efficacy of 1-MCP was enhanced by repeated application. At 20 °C, control fruit (all harvests) softened to less than 50 N pressure within 20 days. For fruit treated once with 1-MCP, fruit of harvest 1 reached this threshold by 63 days, those of harvest 2 after 56 days and those of harvest 3 by 40 days. Fruit treated on a once-per-month basis began to soften by 56 days for harvest 3, while those of harvest 1 and 2 did not. Fruit treated once per week or once per 2 weeks did not soften relative to initial firmness (68N) during the first 63 days of the study. 1-MCP effectively prevented softening at all temperatures relative to the controls, however, as temperature decreased, the benefits of 1-MCP application became less pronounced. Decay was a significant problem for fruit stored at 15 and 20 °C storage temperatures. Roughly 30% to 60% of the fruit were lost to decay in the first 60 days of the study. 1-MCP application reduced, but did not prevent decay. Storage of 1-MCP-treated apple fruit at elevated temperatures will likely require some means of controlling decay in storage.
446 Potted Sunflowers: Production and Postharvest Study
Authors: Pallez Laurence C. , Dole John M. , Whipker Brian E.
Published: February 2019

Days from sowing to anthesis were significantly different among six sunflower (Helianthus annuus L.) cultivars and ranged from 52 days for `Big Smile' to 87 days for `Pacino'. Height ranged from 13.5 cm for `Big Smile' to 37.3 cm for `Pacino'. Postproduction life ranged from 10 days for `Pacino' and `Elf' to 15 days for `Big Smile'. Postproduction quality ratings (1 to 5, with 5 the best) ranged from 3.9 to 5 after 5 days and 1 to 4.2 after 10 days. Quality ratings after 15 days were not significantly different among cultivars, because few plants were marketable at 15 days. Increasing the number of plants per pot from one to three or five reduced number of days to anthesis and postproduction life. Pot sizes of 10-, 13-, or 15-cm diameter, had no influence on production or postproduction characteristics. Promalin (62.5 to 500.0 mg·L–1) was not commercially useful in extending postproduction life. Two cultivars were found to be most suitable for pot production, `Pacino' and `Teddy Bear', with one plant per 15-cm pot and sprayed with B-Nine at 8000 mg·L–1.
447 Predicting Development of Lilium (Asiatic Hybrid) using Thermal Units
Authors: Steininger J. , Pasian C.
Published: February 2019

The objective was to develop a Thermal Units model to be used as a timing tool for two cultivars of Asiatic lilies: `Butter Pixie' and `Horizon'. Two-hundred-eighty-six plants of each cultivar were evaluated over a 2.5-year period. Environmental data were collected using thermocouples and data-loggers. Developmental events observed daily were: shoot visible out of the soil (VS), visible flower bud (VB), and open flower (OF). Rates of development (the inverse of the numbers of days to complete a given phenophase) increased with temperature up to a point. Thereafter, as temperature continued to increase, rate of development either slowed or declined. A piece-wise linear regression change point model was fitted to each data-set using S+ statistical package. This allowed the determination of the base temperature (Tb), optimal temperature (To), and the point of inflection (Ti). Tbs for the phenophase VS:OF of `Butter Pixie' and `Horizon' were – 0.4 °C and 3.0 °C, respectively. The resulting discontinuity of data prompted improvements in the thermal unit calculation formula. Using the new formula, thermal units were calculated. 1,102 °Cd and 833 °Cd had to be accumulated to complete the phenophase VS:OF for `Butter Pixie' and `Horizon', respectively. Predicted date of events were calculated and compared with the observed values. Subdividing the phenophase VS:OF into two (VS:VB and VB:OF) and using their respective Tbs and thermal units requirements reduced the error of prediction to 1.87 d from 2.13 d for `Butter Pixie' and to 1.86 d from 2.39 d for `Horizon'.
448 Cutting the Main Stem of Sunn Hemp Plants Increased Flower Production
Authors: Abdul-Baki A.A. , Bryan H.H. , Zinati G.M. , Klassen W. , Codallo M. , Heckert N.
Published: February 2019

Prolific flowering is essential for economic seed production in sunn hemp (Crotalaria juncea L.). Since flowers appear as racimes on the distal portions of secondary branches and since the branching is restricted by a strong apical dominance, lifting the apical dominance by cutting the tops of plants should induce more branches and more flowers per plant. We evaluated this concept in a field experiment conducted in 1999 at the Tropical Research and Education Center, Univ. of Florida, Homestead, by cutting main stems of 100-day-old plants in a dense stand (113,000 plants/ha) at 30, 60, and 90 cm above the soil surface. Cutting at all heights induced more branching and flowering than the control. The highest positive response was in plants in which the main stem was cut at 90 cm above soil surface.
463 Keeping in Touch While Studying Abroad
Authors: Rhodus Tim
Published: February 2019

Study Abroad programs are designed to provide a variety of learning opportunities for students. Experiencing firsthand the culture, environment, and/or industry is often described as the most memorable benefit by those who study for a quarter or semester in another country. Unfortunately, it is difficult to share this learning experience with classmates and family members who are back at home. One solution that has been implemented with the College's Study Abroad program at The Ohio State Univ., is to design a web site that chronicles the experiences and activities of students while they are abroad. In addition to the photos and stories being contributed from abroad, classmates and other individuals from the home institution can submit questions and participate in threaded discussions with those abroad. For example, students at home can post questions regarding an upcoming tour location and utilize the responses and photos for a class they are attending. Finally, being able to review experiences from previous trips is an outstanding strategy for promoting the program to new students. Online experiences from the Dominican Republic and England programs are available at: http://cfaes.ohio-state.edu/studyabroad.
466 The Reduced Pigment (rp) Gene and Biosynthesis of alpha-Tocopherol in Carrot Roots
Authors: Goldman I.L.
Published: February 2019

Carrots contribute ≈14% of the total Vitamin A to the human diet in the United States due to the presence of the provitamin A carotenoids α- and β-carotene. We have described a recessive gene (rp) that inhibits carotenoid biosynthesis in carrot by 93%, resulting in whitish-yellow roots. The rp mutation is also associated with relatively high levels of a tocopherol (Vitamin E, 0.61±0.15 mg α-tocopherol/100 g FW). Vitamin E is a powerful antioxidant that must be obtained from the diet. The biosynthesis of a tocopherol in carrot has not been studied in any detail; however, the rp gene may provide clues as to its mechanism. The production of carotenoids and tocopherols is biosynthetically linked by their common precursor, geranylgeranyl diphosphate (GGDP). GGDP is converted into phytoene by phytoene desaturase to produce carotenoids and combined with homogentisic acid to produce tocopherols. Carotenoid and tocopherol profiles for various carrot genotypes are presented alongside a model describing the potential relationship between root carotenoids and tocopherols in carrot. The presence of significant amounts of tocopherols in carrot could significantly raise the nutritional profile of this vegetable.
470 Narrow-sense Heritability Estimates for Melon Root Traits
Authors: Crosby Kevin M.
Published: February 2019

Improving melon root systems by traditional breeding is one component of the program to develop multiple-stress-resistant melons at the Texas Agricultural Experiment Station, Weslaco. Ten diverse melon lines representing four horticultural groups were intercrossed utilizing a Design II mating scheme. The male parents were: `PI 403994,' `Perlita,' `Doublon,' `Caravelle', and `PI 525106.' The female parents were: `Créme de Menthe,' `Magnum 45,' `BSK,' `PI 124111 × TDI', and `Deltex.' F1 progeny were grown in pasteurized sand in the greenhouse using a randomized complete-block design with four reps. After 4 weeks, root systems from all plants were carefully washed to remove the sand. Each root system was then placed onto a glass, plated, and scanned into the computer software Rhizo Pro 3.8 (Regent Instruments, Quebec). This software calculated root lengths of various diameter classes, root area, and root tip number. All data was input into Agrobase software for calculation of genetic variances based on Design II analysis. Significant differences of contributions by male parents to progeny variation were few. Only length of roots with 1.0- to 1.5-mm-diameter and vine length were significantly different. Differences in contributions by female parents to all traits except root tip number were highly significant. No significant interaction effects were observed for any trait. Narrow-sense heritability estimates were moderate to high for all traits. The range was from 0.56 for root tip number by males to 0.81 for both length of 0.5- to 1.0-mm-diameter roots and vine length for females. Estimates for total root length (0.76) and root surface area (0.77) were high. The lack of male by female interaction suggests very low dominance genetic variation and contributed to high heritability estimates, which represent predominantly additive gene action. Additive genetic variation allows more-efficient progress by selection, making the potential for root system improvement favorable.
474 High Application Rates of Reclaimed Water Benefit Citrus Growth and Production
Authors: Parsons Larry R. , Wheaton T. Adair , Castle William S.
Published: February 2019

Citrus trees in an experimental planting responded well to high application rates of reclaimed water. Irrigation treatments included annual applications of 400 mm of well water and 400, 1250, and 2500 mm of reclaimed water. The effects of these irrigation treatments on two citrus cultivars (`Hamlin' orange and `Orlando' tangelo) combined with four rootstocks were compared. Growth and fruit production were better at the higher irrigation rates. The concentration of soluble solids in juice was diluted at the highest irrigation rate, but total soluble solids per hectare increased due to the greater fruit production. Average soluble solids/ha production was >15% higher at the 2500-mm rate than the 400-mm reclaimed water rate. While fruit soluble solids were usually lowered by higher irrigation, the reduction in fruit soluble solids observed on three of the rootstocks did not occur in trees on Carrizo citrange. Trees on Cleopatra mandarin grew similarly at the different irrigation rates, but canopy volume of trees on Swingle citrumelo was significantly smaller at the 400 mm rate than at the 2500 mm rate. Fruit peel color score was lower but juice color score was higher at the highest irrigation rate. Weed pressure increased with increasing irrigation rate, but was controllable. Both juice and fruit soluble solids were higher on Swingle citrumelo and lower on Cleopatra mandarin rootstock. Total soluble solids/ha, solids/acid ratio, and juice color were higher on Swingle rootstock. Reclaimed water, once believed to be a disposal problem in Florida, can be an acceptable source of irrigation water for citrus on well drained soils at rates up to twice the annual rainfall.
479 Fruit Characteristics and Productivity of Date Palm Trees (Phoenix dactylifera L.) as Affected by Some Growth Regulators
Authors: Aljuburi Hameed J. , Al-Masry Hasan. , Al-Muhanna Saeed A.
Published: February 2019

Date palm trees are among the most plentiful fruit trees in the Arabian Gulf States. Bioregulators have been used for the improvement of quality and productivity of date plam tree fruits. Application of gibberellic acid (GA3), naphthalene acetic acid (NAA), and ethephon, separately or in a mixture, has significant effects on fruit set, fruit dry matter percentage, fruit soluble percentage, fruit ripening, and yield of date palm trees. A study was conducted to assess relative effectiveness of GA3, NAA, ethephon, and a mixture of growth regulators on some fruit characteristics, and productivity of `Barhee' date plam trees. Five uniform female `Barhee' date palm trees were pollinated on 5–15 Mar. 1994, 1995, and 1996 by placing eight fresh male strands on female spadix centers (flower cluster). Ten flower clusters were used on each tree, and every two flower clusters were subjected to one of the following treatments: control (water), 150 mg·L–1 GA3, 100 mg·L–1 NAA, 1000 mg·L–1 ethephon, and a mixture of growth regulators. The fruit set (%), dry matter (%), total soluble solids (°Brix), fruit ripening (%), and fruit weight (kg per bunch and per tree) were measured. The data showed that the application of GA3 or ethephon on flower clusters of `Barhee' date palm trees had no constant effect on fruit characteristics and productivity of trees. NAA or a mixture of growth regulators reduced fruit dry matter percentage, fruit ripening percentage, and increased fruit weight per bunch and per tree. Spraying `Barhee' date palm flower clusters with NAA or a mixture of growth regulators 20 days after pollination decreased dry matter percentage, fruit ripening, and increased fruit flesh percentage and tree yield.
484 Constructing the BAC Contig for the Evergreen Gene Region in Peach [Prunus persica (L.) Batsch]
Authors: Wang Ying , George Laura L. , Reighard Gregory L. , Scorza Ralph , Abbott Albert G.
Published: February 2019

Evergreen genotypes of peach [Prunus persica (L.) Batsch] have been identified in Mexico, where terminal growth on evergreen trees is continuous under favorable environmental conditions. This evergreen trait in peach is controlled by one single gene (evg), and this evergreen condition is homozygous recessive. Four dominant AFLP markers, EAT/MCAC, ETT/MCCA2, EAT/MCTA, and ETT/MACC, were found to be tightly linked to the evg locus at 1 cM, 4.6 cM, 5.8 cM, and 11 cM, respectively. All four markers were sequenced and identified. A peach BAC library was constructed by using the pBeloBAC11 vector for building the physical map for the evg gene. This library represents four times the coverage of the peach genome with the average insert size of 50 to 70 kb. The EAT/MCAC AFLP marker fragment was used for screening the peach BAC library. A single BAC clone, 18F12, was confirmed to contain this fragment. The final BAC contig for this evg gene region and the potential homology between peach and Arabidopsis thaliana will be presented and discussed.