bluuebunny/crossref_metadata_2025 huggingface dataset:
Inheritance of Characters Important to Drought Tolerance in New Guinea Impatiens (Impatiens hawkeri)
Authors: Quené Robert W. , Strefeler Mark S. , Strope Kerry M.
Published: February 2019

The study was designed to provide information on the inheritance of certain characters important to drought tolerance in New Guinea impatiens. Seven genotypes, three were drought tolerant and four drought susceptible, were crossed in a full diallel with selfs. Drought tolerance of parents was estimated using stomatal conductance. At least 55 seedlings per cross were grown in the greenhouse for 2 months and evaluated for drought tolerance. Leaf fresh weight (LFW) leaf area (LA), leaf length (LL), leaf width (LW), and leaf thickness (LT) were measured using 10 leaves from each plant (parents plus progeny). From these measurements, we calculated LFW/LA and LL/LW. Stomatal conductance was measured on parents plus progeny of three crosses (drought tolerant × drought tolerant, drought tolerant × drought susceptible and drought susceptible × drought susceptible). Heritabilities and nonadditive and additive genetic variance for each trait were determined. All characters were significantly different between families. LFW/LA and LT was positively correlated with drought tolerance. The heritabilities for these traits were high, indicating that these characters can be used for selecting for drought tolerance in New Guinea impatiens and that rapid progress can be and was made in improving drought tolerance in New Guinea impatiens.
Optimization of Microprojectile Bombardment-mediated Gene Delivery into Bisected Axillary Buds of Grape Hybrid Cultivars
Authors: Tapia Maritza I. , Read P.E. , Kaeppler H.F. , Herman P.L.
Published: February 2019

Direct DNA delivery via microprojectile bombardment has been successfully used to transform a wide range of species. Transformation using this system is dependent on the optimization of several parameters. These parameters involve the explant, the gene construct, and parameters in the bombardment system. DNA was delivered into bisected axillary buds of grape hybrids `Chancellor' and `Valiant'. Target tissues were bombarded with gold microprojectiles coated with GUS::NPTII fusion gene construct(pBI426). Several experiments with varying parameters were conducted in order to increase the frequency of DNA delivery. Data were analyzed as a completely random design with 6 single petri dish as a replication and 50-60 bisected axillary buds per replication in each treatment. The treatment design was the single-factor method. Higher frequencies of transient transformation were obtained using microprojectiles of 1.6 μm diameter, adding 0.15 m mannitol and 0.15 m sorbitol, under a pressure of 68.6 cm Hg and a target distance of 6 cm. After 40 days on the selection medium containing 50 mg kanamycin/L regenerated plantlets were obtained and 40% of them expressed the GUS gene. The biolistic approach using bisected axillary buds as target tissue could be a method to achieve stable transformation and transgenic grape plants.
The Effect of Wind on the Vegetative and Reproductive Growth of Four Primocane-fruiting Red Raspberries (Rubus idaeus L.) in the Establishment Year
Authors: Privé Jean-Pierre , Allain N.
Published: February 2019

Four primocane fruiting (PP) red raspberry cultivars, `Bogong', `Cascade', `Heritage', and `Dinkum', were grown in exposed or sheltered (50% permeable artificial windbreak) sites fully exposed to prevailing westerly winds. The cultivars were evaluated to determine the effects of wind stress on vegetative and reproductive development and leaf gas exchange during the establishment year. The artificial windbreak resulted in an overall 35% reduction in wind velocity, increased the number of calm days (<5.4 km·h–1) and decreased the incidence of strong breezes (>36 km·h–1). Concurrently, the artificial windbreak did not have much of an effect on altering relative humidity, air or soil temperature. All cultivars responded similarly to wind exposure Plants in exposed sites had reduced leaf areas, internode lengths, leaf, cane, and total above ground dry weights. Leaf gas exchange parameters (Pn, gs and Ci) expressed per unit leaf area did nor differ between treatments for most of the season but the sheltered plants as a whole supported a greater total leaf area and must have fixed a greater amount of carbon than the exposed plants. These larger sheltered plants produced a more extensive fruiting framework and resulted in a 2-fold yield increase. For these reasons, it is highly recommended to shelter raspberry plants from wind in the establishment year.
Water Use by Three Landscape Trees under Limiting Conditions
Authors: Khoury Ramzy , Tipton Jimmy
Published: February 2019

Evergreen elm (Ulmus parvifolia), southern live oak (Quercus virginiana), and South American mesquite (Prosopis alba) were irrigated at 75%, 50%, and 33% of reference evapotranspiration for 2 years in Phoenix, Arizona. Each tree was irrigated with twenty-nine 3.8-L·h–1 drip emitters to a depth of 90 cm. Initial trunk diameters were about 4 cm. Water use was monitored by heat balance sap flow gauges and related to canopy volume, projected canopy area, and total leaf area. Oak used more water than elm, and elm more than mesquite under all irrigation regimes. Irrigation regimes had a greater effect on oak and elm water use than on mesquite, but all trees maintained an acceptable canopy regardless of treatment.
Effects of Fluorescent Intracanopy Lighting on Cowpea Canopy Productivity and Yield
Authors: Chun Changhoo , Joly Robert J. , Mitchell Cary A.
Published: February 2019

The planophile (horizontal) leaf presentation of closed cowpea (Vigna unguiculata Walp.) leaf canopies limits PAR absorption from overhead lamps to the top layer of overlapping leaves, resulting in suboptimal canopy photosynthesis and premature senescence and abscission of lower, shaded leaves. Very low crop yield rates have been obtained in growth chamber studies using dense cowpea stands compared to greenhouse and field studies using more widely spaced plants. Nine separate growth compartments were constructed in each of two growth rooms. Eight or sixteen 15-W fluorescent lamps were mounted horizontally or vertically in tiers within each compartment, remote from their ballasts, and which can be switched on or off separately according to different lighting strategies. Mylar sleeves around each tube prevents contacting leaves from overheating. Intracanopy lighting arrangements draw from 0.27 to 0.54 kW of power/m3 of growth volume, compared to 1.18 kW·m–3 for traditional overhead lighting. PPF within compartments varies from 80 to 280 mmol·m–2·s–1, depending on sensor location, lamp arrangement, and lamp number. Each compartment is equipped with a recirculating hydroponic system. One room is operated with overhead plus intracanopy lighting, whereas the other utilizes intracanopy lighting only. Cowpea canopies are being grown under different lighting strategies and compared for growth, yield, productivity, leaf orientation, and individual leaf gas-exchange rates. Electrical power draw and total electrical energy consumption are being compared among treatments.
Molecular Properties of Three Soluble Invertase Forms from Lilium longiflorum Flower Buds
Authors: Ranwala Anil P. , Miller William B.
Published: February 2019

Three soluble invertase isoforms from Lilium longiflorum flower buds that had been separated by DEAE-Sephacel chromatography were purified to near homogeneity by further chromatography on hydroxylapetite, Con-A sepharose, phenyl agarose, and Sephacryl S-200 gel filtration. Nondenaturing polyacrylamide gel electrophoresis (PAGE) gave a single band in all three invertases that corresponded to a band of invertase activity in a duplicate gel. The SDS-PAGE of the purified invertase I resulted in a single band with apparent relative molecular mass of 78 kDa. Invertase II and III were resolved to a similar polypeptide pattern by SDS-PAGE with three bands of 54, 52, and 24 kDa. Antiserum of tomato acid invertase cross-reacted with all three invertase protein bands. Antiserum of wheat coleoptile acid invertase cross-reacted only with 54 and 52 kDa bands of invertase II and III but did not recognize invertase I protein. Con-A peroxidase was bound to invertase I protein and all three protein bands of invertase II and III, suggesting that all proteins were glycosylated. Invertase I protein could be completely deglycosylated by incubating with peptide-N-glycosidase F to result in a peptide of 75 kDa. Invertase II and III were partially deglycosylated by peptide-N-glycosidase F resulting proteins bands of 53, 51, 50, and 22 kDa.
Wetting Characteristics of Different Peat and Peat: Bark-based Potting Media: Influence of Wetting Agents in Improving Wetting and Rewetting Performance
Authors: Mane Santakumari , Turner James A.
Published: February 2019

Eight different peat-based or peat: bark-based potting media were evaluated for their wetting performance when treated with the media wetting agent AquaGro 2000 (2–5 oz/yd3). Upon initial irrigation, no differences in wetting uniformity were observed in seven of the eight test media regardless of their media wetting agent treatments. In four media, water retention was reduced by media wetting agent treatment, however, uniform distribution of water was achieved. AquaGro 2000 improved uniformity of initial wetting in one medium in which the initial moisture content was 6.5%. Uniformity of wetting and water retention improved with increasing wetting agent rate. All media were allowed to air dry and then were re-irrigated. Wetting agent-treated media rewet uniformly, while rewetting varied greatly in untreated media (7.5%–82.5%). Less than 50% of the mass of untreated media wet subsequent to drying. Those portions of the untreated media that did wet retained up to three times more water per unit volume compared to AquaGro 2000-treated media. AquaGro 2000 enhanced uniformity of rewetting, reduced water logging, and improved drainage at all rates (2–5 oz/yd3) tested. Media composition (peat vs. peat: bark did not affect wetting agent efficacy.
Effect of Compost Sources and Fertigation Frequency on Growth of Potted Poinsettia
Authors: Ku Catherine S.M. , Bouwkamp John C. , Gouin Frank R.
Published: February 2019

Treatment combinations of four cultivars, 26 mixes, and three fertigation treatments were evaluated in a completely randomized design. Poinsettia cultivars included `V-14 Glory', `Red Sails', `Lilo Pink', and `Annette Hegg'. The 26 mixes were 25%, 33%, and 50% of eight compost sources blended with 1 peat: 1 perlite (v/v), and Sunshine mix and Pro-Gro were the control. The eight compost sources were yard waste, lime and polymer dewatered biosolid, municipal solid waste (MSW), co-composted MSW 1 and 2, crab waste, and poultry litter. Fertigation treatment was began on first, second, or third week after potting. Fertigation solution was 250 mg/L N from 21N–2.2P–15.8K. The controls produced premium quality plants with 38 cm in canopy diameter, 11 total number of branches, and 28 cm in shoot height. Poultry litter, yard waste, polymer dewatered biosolid, crab waste, and MSW produced good quality plants with canopy diameter ranging from 30 to 35 cm. The canopy diameter with 25% compost treatments were 6% to 20% greater than those with 50% compost treatments. Total number of branches, shoot height, canopy diameter, and plant grade with first week fertigation were only 3% greater than those with fertigation delayed 1 or 2 weeks.
Pulse Irrigation Strategies for Poinsettias
Authors: Moody D. Sean , Newman Steven E. , Hopper Douglas A.
Published: February 2019

Three irrigation strategies [10% leaching, 0% leaching (pulse), and ebb-and-flood] and two constant liquid feed fertilizer treatments, 150 and 300 ppm N, were applied to poinsettias, `Freedom Red' and `V-17 Angelika Red', with a harvest date of November 25, 1995. There were no differences in plant dry weights among the three irrigation strategies at the 150 ppm N treatment. At 300 ppm N, 10% leaching irrigation grew plants with the greatest dry weights, followed by the ebb-and-flood treatment and the pulse treatment, respectively. The 10% leaching and ebb-and-flood plants had the greatest growth index, while the pulse treatment growth index was lower. Growth index was greatest for the 10% leaching strategy for `Freedom Red', while ebb-and-flood had the lowest index. The growth index was greater at 150 ppm N for `Freedom Red' compared to 300 ppm N. `V-17 Angelika Red' was not influenced by fertility level. Pulse irrigation grew marketable poinsettia plants at lower fertility levels.
Fine Population Structure of Discula destructiva
Authors: Caetano-Anollés G. , Trigiano R.N. , Windham M.T.
Published: February 2019

Fifty-one isolates of Discula destructiva obtained from various Cornus species were evaluated using arbitrary signatures from amplification profiles (ASAP). ASAP analysis is based on dual-step arbitrary primer-based amplification procedure that produces “fingerprints of fingerprints” and in many instances increases detection of polymorphic DNA. This novel technique was able to distinguish groups of isolates from the northeast, middle and southeast range of the disease as well as western United States and Canada. The data supports the contention of recent and independent introduction of the disease on both east and west coasts, a genetic “bottleneck” that has limited diversity of the pathogen, and directionality of introduction of disease from coastal ports-of-entry to interior populations of C. florida and C. nuttalli.
Teaching in the Virtual Classroom: Using Internet and Computer Resources to Enhance Educational Opportunities in a General Plant Sciences Class
Authors: Rom Curt R.
Published: February 2019

To enhance the opportunities for students to access information and the instructors of a large, general plant science class, “Virtual Classroom” concepts using computers resources were implemented. The Virtual Classroom uses three computer resources: 1) a closed subscription LISTSERV for the extramural class discussions, 2) electronic mail for homework assignment and submission, and 3) a World Wide Web Internet homepage for the course. In a large, introductory-level class, student–teacher interaction can be limited. The size of the class and the content may inhibit questioning and discussion among the class participants. The LISTSERV allowed for questions to be posed by students at their leisure and facilitated discussion among students and the instructor outside of the confines of the class meeting. The LISTSERV also allowed instructors to to respond to the students by referring questions to “experts” on a particular subject. Using e-mail for homework assignment and submission was useful for tracking when student read assignments and submitted completed assignments. Electronic assignment grading and returning was paperless and easy for instructors to maintain. The homepage provided students with a permanent syllabus, lecture outlines, homework assignment descriptions, and study aids. Additionally, from the homepage students were able to send e-mail to instructors and search library databases and other electronic databases. Experiences from the instructors using these computer resources will be presented and discussed.
Postharvest Application of Natureseal Heat Treatments for Extending the Shelf Life of Stored Blueberries
Authors: Basiouny Fouad M.
Published: February 2019

Fruit of Rabbiteye blueberry (Vaccinium ashie Reade cv. `Tifblue') were hand-picked at horticultural maturity and received postharvest liquid coating and heat treatments at 37.7°C for 30 minutes. After precooling for 2 hours and subjected to the treatments, fruit were placed in ventilated card boxes and stored at 1 ± 2°C and 90% to 95% relative humidity for 4 weeks. Heat, liquid coating, or both benefited fruit by reducing storage moisture loss and prolonging fruit shelf life compared to nontreated fruit. However, combining liquid coating with heat treatment did not result in higher differences in storability or fruit quality characteristics.
Evaluation of Stomatal Density and Calcium Concentration on Pods of Six Commercial Cultivars of Snap Beans (Phaseolus vulgaris L.) at Four Planting Dates
Authors: Quintana Juan M. , Harrison Helen C. , Nienhuis James , Palta Jiwan
Published: February 2019

Pod stomatal density and Ca concentration levels were analyzed for six commercial snap bean cultivars harvested at four planting dates in an attempt to find morphological traits that are related to cultivar differences in pod Ca concentration. The experimental layout was a randomized complete-block design with two replications per planting date, all grown in one location. Snap beans were planted at 1 week intervals beginning 9 June 9 1995 and were harvested in August. Sampling consisted of five pod sizes (1, 2, 3, 4, and 5 according to commercial standards) from each genotype. Stomatal countings were performed using a microscope linked to a television camera. Determinations for pod Ca concentration were made using an atomic absorption spectrophotometer. No differences were detected for pod Ca concentration among planting dates, although there were differences for pod Ca concentration and stomata density among cultivars. Pod stomatal density was positively correlated to pod Ca concentration (R2 = 0.60), while pod maturity appeared to be negatively correlated to pod Ca concentration (R2 = 0.37) and pod stomatal density (R2 = 0.49).
The Earth Box: A Containerized Gradient Concept
Authors: Geraldson C.M.
Published: February 2019

The Earth Box, a completely enclosed system made of recycled plastic, is designed to provide a continuing source of water and nutrients to replace that as removed by the crop. Nutrients move by gradient from a surface source to the root; water moves to the root by seepage upward from a water reservoir. The Box holds 2.3 cubic feet of media (soil or potting mix) supported on an aeration screen 0.5 inch above a water reservoir that holds 2.3 gallons. The total concept is designed to synchronize the nutrient–water input with removal, thus, providing an undiminishing nutritional stability in the soil solution. Two tomato plants per box have produced 30 to 50 pounds of fruit with a quality that reflects the continuing optimal nutrition. Other vegetable crops, strawberries, and flowers have been grown in the Earth Box with similar results. Nutritional stability in the conventional soil solution can deteriorate with variations in the soil-plant-season, which limits productivity. Whereas with the gradient, nutritional stability is constant regardless of the soil-plant-season or whether grown in the field or a container. The gradient procedure is not conventional or hydroponic; hydroponic cultures are nutritionally stable to begin with, but like conventional procedure, that stability is vulnerable. The gradient concept, whether it be in a container or in the field, has the potential to become a globally sustainable production system—minimal water, minimal pollution, minimal management with a maximum productivity. The Earth Box is primarily for the home gardener but the feasibility as a commercial edition is now being evaluated.
Extending Crop Nutrient Information: Involving the Whole Industry
Authors: Lamberts Mary , Olczyk Teresa , O'Hair Stephen K. , Carranza Juan , Bryan Herbert H. , Hochmuth George , Hanlon Edward
Published: February 2019

Replicated fertility trials with four vegetable crops on the limestone soils of Dade County, Fla., have been conducted for 3 years (1993–94 through 1995–96). The purpose was 1) to determine crop nutrient requirements, 2) to calibrate a soil testing model, and 3) to develop additional information for plant sap quick tests. The crops included snap beans, Irish potatoes, sweet corn, and malanga (a.k.a. yautia or tannia, Xanthosoma sagittifolium Schott). Another two field demonstrations using reduced rates of phosphorus on tomatoes were conducted in 1995–96. The involvement of the local fertilizer industry in these trials and grower outreach efforts will be discussed.
Addressing Organic Sustainable Growers' Needs
Authors: Hadad Robert
Published: February 2019

Organic production of vegetable and fruit crops in Kentucky is gaining ground. Acreage and grower numbers are increasing. Health concerns and certain economic advantages for the grower are the impetus for rise in organic production. There is a need to collate cultural practice information and present it in a usable form for Kentucky. Work is being done to consolidate information on cultural practices, current research, and marketing opportunities. To address these concerns, older extension horticultural publications are being amended and new bulletins are being written. To accomplish this, grower meetings, farm visits, scouting for problems in crops, conducting research, and sifting through literature are some of the steps being taken. The greater implementation of cultural practices such as rotations, cover crops, green manures, living mulches, and minimum tillage are helping to reduce dependence on chemical sprays, chemical fertilizers, and soil destroying practices. Through this liaison, we are bringing together a new group of agricultural producers with interdepartmental specialists within the university and new insights and partnerships are being forged.
Restriction Enzyme Analyses of Cytoplasmic Diversity in Leek
Authors: Leite D.L. , Havey M.J.
Published: February 2019

Hybrid leek (Allium ampeloprasum) is significantly more uniform and higher yielding than open-pollinated populations. Because leek has perfect flowers, a male-sterility system is required to produce hybrid seed economically. No cytoplasmic male sterility (CMS) has been described in leek. Restriction fragment length polymorphisms (RFLPs) in the chloroplast and mitochondrial genome have correlated with the expression of CMS in many crops. We undertook restriction-enzyme analyses of the chloroplast and mitochondrial DNAs to identify polymorphic organellar genomes among 65 accessions of cultivated leek. Polymorphisms were detected in the chloroplast and mitochondrial genomes. Reciprocal crosses were generated to establish the transmission of the organellar genomes of leek.
Comparison of Strawberry F. chiloensis and F. ×ananassa in Response to Water Stress: II. Leaf Fluorescence, Chlorophyll Content, and 4th-derivative Spectra
Authors: Chen Chuhe , Cameron J. Scott , Klauer Stephen F.
Published: February 2019

Leaf fluorescence characteristics, chlorophyll (Chl) content and 4th-derivative spectra were measured six times before, during, and after water stress development in F. chiloensis and F. ×ananassa grown in growth chambers. The younger strawberry leaves under water stress maintained higher Chl a, Chl b, and total Chl contents than those under nonstressed conditions, while the older ones lost Chl quickly under water stress and then died. In comparison to F. ×ananassa, F. chiloensis had significantly higher Chl a, Chl b, and total Chl contents and peak amplitudes of Cb 630 and Ca 693 in 4th-derivative spectra under stressed and nonstressed conditions. The differences in peak amplitude of Ca 693 between the two species increased under water stress. Fq was the most sensitive fluorescence characteristic to water stress and was reduced significantly under stress. Fm and Fv decreased significantly under more severe water stress. A reduction in Fv suggests that severe water stress might cause thylakoid damage and photoinhibition in the leaves, which resulted in a very depressed CO2 assimilation level. F. chiloensis had significantly higher Ft and Fq before and under water stress development (but not after stress recovery) than F. ×ananassa.
Effect of Rootball Size On Growth, Leaf Nitrogen Content, and Total Stem Nonstructual Carbohydrate Content Of Landscapesized Sugar Maple
Authors: Harris J. Roger , Knight Patricia , Fanelli Jody
Published: February 2019

Two rootball sizes as well as a nontransplanted control were randomly assigned to Acer saccharum Marsh. (sugar maple) trees in four adjacent nursery rows at Waynesboro Nurseries in Waynesboro, Va. One size (75 cm in diameter) corresponded to the American Association of Nurserymen standards. The other rootball size was 90 cm in diameter. Trees were transplanted just before bud swell or during shoot elongation. Rootball size had no effect on height, stem diameter, or twig growth, total nonstructual leaf nitrogen content (LNC), or total stem nonstructual carbohydrate (TNC). Height growth was reduced by 81%, stem diameter growth by 71%, and twig growth by 82% for trees transplanted before bud swell compared to nontransplanted trees. LNC was 25% more on transplanted trees than on nontransplanted trees, presumably due to a dilution effect. TNC was 20% higher on transplanted compared to nontransplanted trees. Growth was severely curtailed on late-transplanted trees for all characteristics measured compared to all other treatments.
Nutrient Management for pH Control in a Controlled Ecological Life-support System
Authors: Lea-Cox John D. , Stutte G.W. , Berry W.L. , Wheeler R.M.
Published: February 2019

Maintaining pH to optimize nutrient availability in unbuffered nutrient solutions is important for closed spaceflight hydroponic systems and in agriculture. Total nutrient uptake is reflected by electrical conductivity (EC) measurements, while pH reflects the net imbalance of cation and anion absorption. The pH of nitrate-only (0 : 100 ) nutrient solutions normally increases, whereas with equimolar (50 : 50 ), solutions, pH decreases. However, when solution pH was controlled to 5.8 by a mixed N sources (25 : 75 ), plant yields of semi-dwarf wheat (Triticum aestivum cv. `Yecora Rojo') were equal to the control (0 : 100 ) system. When nutrient uptake was monitored at 15-min intervals, it was found that and were taken up simultaneously. Uptake of was more rapid than . The change in pH and EC was primarily a function of the absorption of three ions, namely , , and K+. A significant amount of the K+ uptake was highly correlated (P < 0.001) to the presence of in solution. When the daily N requirement was supplied as a 25 : 75 mixture, comparatively little change in solution pH occurred, with reduced K+ uptake by the plants. Thus, by knowing the daily crop N requirement from the relative growth rate, the pH fluctuations within hydroponic nutrient solutions can be reduced with daily additions of a balanced nutrient solution with a 25 : 75 mixture of N.
Characterization and Use of Nitrogen Contained in Sweet Corn Silage Waste in Cropping Systems
Authors: Fritz Vincent A. , Randall Gyles W. , Rosen Carl J.
Published: February 2019

Sweet corn silage waste is ≈18% dry matter and contains 1.2% N and 0.26% P on a dry-weight basis. Silage waste in rates of 0 to 448 T·ha–1 was applied to a previously harvested sweet corn field in late summer. Beginning the following spring, soil samples were periodically collected to follow the rate of N mineralization. Field corn was planted to the site the following spring as the test crop. At harvest, grain, stover, and silage yields were recorded and N removal from the system was followed through grain and tissue sampling. Additional studies were also conducted to evaluate the impact of primary tillage method on subsequent N mobilization from sweet corn silage waste and to assess the residual N release potential beyond the first year following silage waste application. Results suggest that land application of sweet corn silage waste at 224 T·ha–1 would be environmentally responsible, provided that adequate nitrogen credit from the silage waste is integrated into the total nitrogen needs of the subsequent crop. Greater mineralization is achieved when the silage waste is moldboard plowed compared to chisel plowing. Chisel plowing could result in greater residual N carryover during the year following silage waste application. Seedling emergence rates were faster and grain yield was superior in some years in moldboard-plowed plots compared to chisel-plowed plots. Further calibration of additional N fertilizer on land that received silage waste is necessary for improved production efficiency and sweet corn silage waste use in production systems.
Isozyme and RAPD Analyses of Witch Hazel Cultivars
Authors: Marquard Robert D. , Chan Charlotte R. , Davis Eric P. , Stowe Emily L.
Published: February 2019

Numerous isozyme systems were found to be polymorphic in witch hazel (Hamamelis spp.). However, aconitase (ACO), malate dehydrogenase, phospho-glucose isomerase (PGI), and phosphoglucomutase were most useful for identification of cultivars. From these enzyme systems, three genes were identified that control patterns of ACO (2) and PGI (1). Isozymes can be used to help verify cultivars and their simple inheritance could be useful to validate hybrids and gene flow between plants. DNA was readily extracted from young leaf tissue after grinding in liquid nitrogen and extraction in warm CTAB. DNA was amenable to amplification using polymerase chain-reaction technology. Primers (400) were screened to identify polymorphic RAPD bands. Ultimately, 19 primers were used to generate 68 RAPD markers that were reproducible. Cultivars were scored for presence or absence of the 68 markers. Genetic similarities were calculated using a Nei coefficient and clustering was conducted for more than 40 cultivars using a UPGMA program. Arbitrarily, the cultivars were assigned to seven groupings after cluster analysis. The seven classes gave one group each of H. japonica and mollis; two groups of H. vernalis; and three groups of H. ×intermedia. Clustering allowed some interpretation about relatedness among cultivars and genetic similarity data helped assign some cultivars to a particular taxa that were previously in question.
Integration of Genetic Linkage Maps of BC1 and F1 Populations of the Intergeneric Cross of Citrus grandis × Poncirus trifoliata Using RAPD Markers
Authors: Weber Courtney A. , Moore Gloria A.
Published: February 2019

A greater saturation of the previously constructed genetic linkage map of Citrus is important in the long term goal of mapping quantitative trait loci (QTL) such as those controlling cold and salt tolerance. Segregation for cold tolerance appears to be greatly enhanced in the intergeneric F1 population of Citrus grandis × Poncirus trifoliata as compared to the BC1 population previously used for mapping due to the higher percentage of P. trifoliata genes present. This is not unexpected since P. trifoliata is the source of cold tolerance in this cross and is a highly heterozygous species. An integration of the maps of the two populations using about 50 random amplified polymorphic DNA (RAPD) markers common to the two populations is possible using the JoinMap computer program. This will allow the placing of approximately 100 new polymorphic RAPD markers from the F1 population identified by screening from 42 random oligonucleotide primers onto the Citrus map. This saturated map will be used to locate QTL following bulk segregation analysis of cold tolerance in the F1 population.
Genotype of Flowering Stems of Antirrhinum majus L. Influences Ethylene Evolution and Fresh Weight Changes Postharvest
Authors: Stimart Dennis P. , Schroeder Kenneth R.
Published: February 2019

Cut flowers of a short (S)-lived (3-day) inbred, a long (L)-lived (15-day) inbred and their hybrid (F1, 7.3 days) of Antirrhinum majus L. were evaluated for fresh weight and ethylene evolution change postharvest when held in deionized water. Fresh weight change of all accessions increased 1 day postharvest then declined over the remainder of postharvest life. The loss of fresh weight was most rapid for S and less rapid for F1 and least rapid for L. Ethylene release postharvest for S and F1 started on day 1, but for L ethylene release started on day 9. Once ethylene evolution began it continued through postharvest life. On the last day of postharvest life, ethylene release from S and F1 were similar, but L was twice the level as S and F1. It appears that a slower decline in fresh weight, a delay in outset of ethylene release and higher final amount of ethylene release at senescence are heritable and associated with longer keeping time of A. majus.
Crossability of 14 Rubus Species with Red Raspberry and Blackberry Cultivars
Authors: Finn Chad , Wennstrom Kirsten , Hummer Kim
Published: February 2019

Populations of 40 Rubus sp., representing the Malachobatus, Idaeobatus, Eubatus, and Anoplobatus, were planted in the field in 1994. To get a preliminary idea of how successful crosses between these species and standard cultivars would be, 58 crosses were attempted between standard cultivars and randomly selected genotypes of the 14 species that produced a significant number of flowers in 1995. Diploid species were crossed with `Tulameen' and `Meeker' raspberry and the tetraploid species with `Cherokee' and `Chester' blackberry. Twenty-two crosses produced seed lots ranging from 8 to 630 seeds. Crosses were successful with R. caesius, R. caucasicus, R. coreanus, R. georgicus, R. parvifolius, R. rosifolius, and R. sumatranus. Crosses were not successful with R. eustephanos, R. insularis, R. innominatus, R. lambertianus, R. sachalinensis, R. setchuenensis, R. swinhoei, and R. tsangorum. In vitro seed germination was attempted with all crosses. Larger seed lots were also germinated using standard procedures for Rubus. There is a great deal of variability in leaf morphology of the young seedlings within a cross that suggests that some or all of the seedlings are true hybrids. Seedlings that are not true hybrids could result from contaminant pollen or, as in R. armeniacus, pseudogamous embryo formation. Crossing results from 1995 and 1996, including crosses attempted and seed numbers per cross, will be presented along with, for the 1995 crosses, the number of germinated seedlings and our assessment of whether they appear to be true hybrids.
Evaluation of Scotch Bonnet and Habanero Peppers (Capsicum chinense) For Resistance to Southern Root-knot Nematodes
Authors: Fery R.L. , Thies J.A.
Published: February 2019

Scotch Bonnet and Habanero peppers, extremely pungent cultivar classes of Capsicum chinense, are becoming popular in the United States. Since the southern root-knot nematode (Meloidogyne incognita) is a major pest of many C. annuum cultivars commonly grown in the United States, a series of greenhouse and field studies was conducted to determine whether Scotch Bonnet and Habanero peppers also are vulnerable to the pest. An effort was made to collect Scotch Bonnet and Habanero seeds from all available commercial and private sources. In an initial greenhouse test, a collection of 59 C. chinense accessions was evaluated for reaction to M. incognita (race 3). All accessions obtained from commercial sources were moderately susceptible or susceptible. However, four accessions obtained via Seed Savers Exchange listings exhibited high levels of resistance. Three of these accessions (identified by the seed sources as Yellow Scotch Bonnet, Jamaica Scotch Bonnet, and Red Habanero) were studied in subsequent greenhouse and field plantings, and each was confirmed to have a level of resistance similar to the level of resistance exhibited by the C. annuum cv. Mississippi Nemaheart. Each of the resistant lines has good fruit and yield characteristics. The two Scotch Bonnet accessions produce yellow, bonnet-shaped fruit. The Red Habanero accession does not produce the lantern-shaped fruit typical of Habanero cultivars; the fruit have a bonnet shape.
Cytological and Morphological Characterization of Amphidiploids for Rose Breeding
Authors: Ma Yan , Byrne David H. , Porter Katrina G.
Published: February 2019

Several colchicine-induced amphidiploids of blackspot-resistant, wild diploid rose species were produced for interbreeding with tetraploid garden roses. Shoot-tip chromosome counts confirmed that 86-7 (Rosa wichuraiana Crep. × R. rugosa rubra Hort.) and 86-3 (R. laevigata Michx. × R. banksiae Aiton) are amphidiploids (2n = 4x = 28), and that 84-1000 (R. roxburghii Tratt. × R. laevigata Michx.) is a mixoploid with diploid (2n = 2x = 14) and hypotetraploid (2n = 4x-1 = 27) sectors. The measured volume of pollen grains and guard cells was higher in the tetraploids. Pollen stainability was higher in amphidiploids 86-3 and 86-7 than in mixoploid 84-1000. The amphidiploid 86-7 has greater pollen fertility as determined by crossing with a range of commercial tetraploid roses than 86-3 and 84-1000, but is less fertile than its parental diploid species. Leaflets of the amphidiploids are larger and more crinkled along the midrib than in their diploid parents. These three amphidiploids provide new additions to tetraploid rose germplasm.
Pollination Methods for Cornus Breeding
Authors: Craddock James Hill , Sauve R.J. , Schlarbaum S.E. , Skinner J. , Trigiano R.N. , Windham M.T. , Witte W.T.
Published: February 2019

Hand pollinations and honey bees were used to cross Cornus florida cultivars in a series of experiments investigating dogwood pollination biology from a breeding viewpoint and testing the use of insects (domestic honey bees and ladybug beetles as pollinators in dogwood breeding. Experiments were conducted to study possible incompatibility between dogwood cultivars and to determine if self-compatibility and self-fertility occur in Cornus florida. Since 1993, ≈200 seedlings have been produced by hand and insect-mediated pollinations. Honey bees can be used in dogwood breeding. Trees cross pollinated by ladybeetles had lower fruit set than trees cross pollinated by honey bees. Greenhouse forcing to accelerate anthesis and cold storage to delay the onset of bloom of container-grown trees can extend the dogwood breeding season effectively.
Regeneration of Panax ginseng C.A. Meyer by Organogenesis and Nuclear DNA Analysis of Regenerants
Authors: Lim Hak-Tae , Lee Haeng-Soon , Eriksson Tage
Published: February 2019

Plant regeneration ability of ginseng (Panax ginseng) via organogenesis was studied morphologically and anatomically. Compact callus was introduced from four different types of explants—leaf, petiole, flower stalk, and root—of in vitro-grown plantlets. Petioles were found to be the best material for callus induction. Calli induced on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid (1.0 mg·L–1) and kinetin (0.1 mg·L–1) were conditioned for 2 weeks on the same medium. These calli differentiated into adventitious shoots when cultured on half-strength MS basal medium plus kinetin at 1.0 mg·L–1 and STS at 2.5 mg·L–1. An addition of GA3 (1.0 mg·L–1) and BA (1.0 mg·L–1) to MS basal medium, however, induced high-frequency in vitro flowering (86.1%) and multiple shoot budding, which affected the normal, complete development of plantlets. Plantlets with well-developed root systems were obtained 6 weeks after regenerated shoots had been transplanted to half-strength MS20 medium containing IBA at 0.25 mg·L–1. Nuclear DNA content was measured to check the stability of their ploidy level. Based on DNA flow cytometric analysis, all of the regenerants were typically diploids as were the mothers plants, indicating that nuclear DNA content remained stable during cell differentiation.
Root Growth and Organogenesis in Thidiazuron-treated Ginseng (Panax quinquefolium L.)
Authors: Proctor J.T.A. , Slimmon T. , Saxena P.K.
Published: February 2019

Ginseng is an herbaceous perennial that grows in the understorey of deciduous hardwood forests and is also cultivated for its highly valued root. The primary method of propagation of ginseng is by seed which requires the breaking of dormancy by stratification, a process which takes 18–24 months. Investigation of factors controlling the growth and development of ginseng plants is a prerequisite to the development of a more efficient system of ginseng propagation. We have recently modulated the morphogenetic potential of geranium roots and stimulated de novo development of shoots and embryo-like structures which later formed whole plants using thidiazuron (TDZ). Our objective was to investigate the morphological changes in seedling and mature ginseng plants induced by TDZ, particularly in relation to root and shoot morphogenesis and economic yield. Applications of TDZ (0.22 and 2.20 ppm), either as foliar sprays or soil watering to greenhouse-grown seedlings over 18 weeks (2 weeks after sowing to 20 weeks when plants were harvested) induced similar effects. These responses included increased stem length and diameter, and shoot and root weight (economic yield). Single foliar applications of TDZ at 62.5 and 125 ppm to 3-year-old field-grown ginseng plants 3 months before harvest increased root biomass (economic yield) by 19% to 23%. Roots of TDZ-treated seedlings and 3-year-old field-grown plants developed thickened secondary roots on the upper part of the taproot. The root-like structure of these secondary roots was confirmed by histology. In addition, TDZ treatments induced adventitious buds on the shoulder of 3-year-old roots. These buds developed into shoots to give multi-stem plants following a period of dormancy, which was overcome with GA3 (gibberellic acid) treatment before planting.
Partial Organogenesis and Somatic Embryogenesis from Petiole Explants of Field-grown Papaya (Carica papaya L.)
Authors: Jayasankar S. , Yadava U.L
Published: February 2019

Petiole discs from young leaves of female papaya (L-45) plants were cultured in MS or B5-based media containing 0, 2.25, 4.5, 11.25, and 22.5 μm 2,4-D. Compact embryogenic callus emerged from vascular tissue of petiole discs in about 3 weeks. In MS medium, 66% and 51% explants formed embryogenic callus with 11.25 and 22.5 μm 2,4-D, respectively. On the other hand, 79% explants formed embryogenic callus in B5-based medium with 4.50 μm 2,4-D. However, explants became necrotic in B5-based medium with 22.5 μm 2,4-D. Subculturing callus in auxin-free medium resulted in the development of roots or somatic embryos. Microscopic observations revealed that the roots were produced only by the callus that had retained its continuity with the vascular tissue. This investigation revealed that petioles from field grown papaya plants are potential explants for somatic embryogenesis and 2-week exposure to 2,4-D is adequate for inducing morphogenesis. Additionally, an interaction between 2,4-D and the components in the MS and B5-based media was observed.
An in Vitro Potato Bioassay to Investigate Tuber Inductive Factors in Continuously Reused Hydroponic Nutrient Solutions
Authors: Yorio N.C. , Stutte G.W.
Published: February 2019

An experiment was conducted in the Biomass Production Chamber (BPC) at Kennedy Space Center to examine the effects of using continuously reused nutrient solution in an NFT system to support potato growth in batch and continuous planting scenarios. Tuberization was hastened and plant growth reduced on plants grown in the aged nutrient solution. We have previously reported that the effect is removed when the aged nutrient solution is filtered through activated charcoal. In order to investigate this apparent plant growth regulator response, an in vitro bioassay has been developed that allows for repeatable, small scale, and rapid testing of the tuber-inducing response. The bioassay is a liquid culture system that employs 600-mL Berzelius beakers capped with modified Sun transparent tissue culture bags, a light shield around the root zone, and a polyurethane foam support, which holds a micropropagated potato plantlet. With this bioassay, we have observed the same plant stunting and tuber initiation effects that were previously seen with the aged nutrient solution. The bioassay appears to be sensitive to environmental factors (PPF, photoperiod, and temperature) that influence tuberization. In addition, partially purified preparations of the apparent growth regulators have elicited the tuberization response. Currently, efforts are underway to examine the role of the microbial community associated with the BPC nutrient delivery system on the tuberization response.
Propagation of Pistachio Trees Using Epicotyl Grafts
Authors: Talaie A. , Javanshah A.
Published: February 2019

Methods to shorten the required fruiting period for pistachio may reduce production costs. Therefore, grafting is recommended. We examined three grafting methods: fabble, cleft, and side. Fabble grafts had 66% success and therefore a higher efficiency than the other two types of grafts examined. BA or ascorbic acid did not have a considerable positive effect on graft healing and there may have been some negative effects. The results of microscopic dissection show that healing between rootstock and scion, i.e., formation of callus, xylem, and phloem tissues in the epicotyl stage, are similar and the plants propagated by epicotyl grafts enjoy maturity signs from ontogeny points of view in two growing seasons.
Effects of Low O2 on the Timing of the Onset of the C2H4 Climacteric and Subsequent Ripening of `Gala' Apples at 1°C
Authors: Solomos Theophanes
Published: February 2019

We have investigated the effects of different O2 concentrations on the onset of the climacteric rise in C2H4 evolution and subsequent ripening of `Gala' apples. The data show that the effect of low O2 on the timing of the onset of the C2H4 climacteric is saturable in that for low O2 to retard the onset of the rise in C2H4 evolution its concentration must be decreased below 8%. Further, the results suggest that the retarding effects of low O2 on the onset of ripening cannot be ascribed to the inhibitory effects of low O2 on the action of the low levels of C2H4 evolution by preclimacteric apples. The results concerning the rate of C2H4 evolution and accumulation of the ACC-oxidase protein show that application of low O2 after the initiation of the climacteric rise in C2H4 is not as effective in delaying senescence as when it is imposed early, i.e., at the preclimacteric stage.
Changes in Hemicellulose-associated Pectin during Softening of Peach Fruit
Authors: Hegde Supreetha , Maness Niels O.
Published: February 2019

Softening to a normal melting flesh texture in peaches involves a combined participation between polymers located in the middle lamella and primary cell wall. Pectins located in the primary cell wall polysaccharide matrix which cosolubilize when hemicellulose is extracted with KOH have received less attention than the chelator or sodium carbonate soluble pectin likely to be associated with the middle lamella. We conducted a series of extractions for cell walls prepared from softening peach fruit (47, 30, and 15 N firmness) using 0.5 m imidazole, sodium carbonate and a graded series of KOH. Hemicellulose-associated pectin was a substantial proportion of most KOH extracts (30 to 50 mole percent) and fractionated on size exclusion chromatography as a high apparent molecular weight peak which became more prominent as fruit softened and could be separated from two lower apparent molecular weight peaks by anion exchange chromatography. The nature of a hemicellulose-pectin interaction in peach was apparently by physical entrapment, versus covalent cross-linking. Softening related changes in hemicellulose-associated pectin will be addressed.