bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Norwegian Open-Source Plug-and-Abandonment Database With Applications
Authors: Myrseth Velaug , Perez-Valdes Gerardo A. , Bakker Steffen J. , Midthun Kjetil T. , Torsæter Malin
Published: January 2017

An estimated 3,000 oil wells need to be plugged and abandoned on the Norwegian Continental Shelf (NCS), with approximately 150 new wells being drilled each year. The petroleum industry estimates the total plugging costs to be almost 900 billion Norwegian kroner (NOK), and that the work will take up to 40 years to complete. Because of the current tax regulations in Norway, the state indirectly pays 78% of the costs (approximately 700 billion NOK). It is therefore vital to reduce expenses by targeted research and development (R&D) of new technology, and to ensure better planning of plug-and-abandonment (P&A) operations in and between licenses.

The current study aims to gather available data relevant for Norwegian P&A operations in an open-source database, and to develop and use a P&A planning software that serves as a decision-support tool for various problems operators face. The software can be used to generate planning schedules, identify bottlenecks in P&A operations, and analyze potential efficiency gains from technology improvements and cooperative plugging campaigns. We will use a cross-disciplinary approach that combines the fields of operations research with technological expertise.

In this paper, we present the outline of the database and the current status of available data for P&A operations on the NCS, as well as a short literature review. Available data are categorized according to the different choices that need to be made within a single P&A operation, with regard to both technological aspects and the existing regulatory framework. We also discuss the type of analysis the P&A planning software is envisioned to perform.

Industry, government, and ordinary tax payers will all benefit from knowledge sharing, optimized planning, and more targeted R&D efforts on this topic. The results from this study will be used to identify important cost drivers and to draw up a roadmap for future P&A-related R&D.
Laboratory Testing on Proppant Transport in Complex-Fracture Systems
Authors: Li Nianyin , Li Jun , Zhao Liqiang , Luo Zhifeng , Liu Pingli , Guo Yujie
Published: January 2017

In the fields of unconventional gas and tight oil development, stimulated-reservoir-volume (SRV) fracturing is a key technology. Injecting low-viscosity sand-laden fluid at a high flow rate has the capacity to form complex-fracture networks. Therefore, placing proppant deep into these complex-fracture networks results in a conductive path for production enhancement. In addition, this technique reduces flow resistance when fluid flows from the rock matrix to the wellbore.

Currently, the sand features in low-viscosity, sand-laden, high-flow-rate fluid are not fully understood. How this type of fluid can be used for proppant transportation in subsidiary fractures is particularly unclear. This study offers a full exploration of the practical conditions of engineering. Considering the similarity criterion of geometry and velocity, this experiment features the construction of a large-scale device used for proppant placement in visualization of complex-fracture networks. The device can change fracture angles, width, and quantity. Building on the single factors experiment, this paper presents a series of tests to evaluate the transport of proppant in complex-fracture networks. A variety of slickwater-treatment tests are simulated by pumping sand slurry through the visualization-of-complex-fracture-networks device while varying parameters of perforation, fracture angles, proppant size, pump rate, and proppant concentration. As the experiment shows, treatment tests that are used with variable factors obtain different laws regarding traction-carpet features, traction-carpet areas, and balance height and time in complex-fracture networks. In addition, this paper describes a 3D physical model designed by SolidWorks (2011) grid software to make complex-fracture grids. The paper also discusses the process of simulating proppant-concentration-distribution fields in a model of complex-fracture networks. A comparison of the results between the physical and numerical models reveals that during the process of SRV, the law of proppant placement in complex-fracture networks can serve as a guideline for engineering design.
Nanoparticle-Enhanced Hydraulic-Fracturing Fluids: A Review
Authors: Al-Muntasheri Ghaithan A. , Liang Feng , Hull Katherine L.
Published: January 2017

Hydraulic-fracturing fluids are used to break down subterranean formations where oil and gas are trapped. Pad or prepad fluids are first pumped into the formation to generate the fracture geometry. Once the fracture geometry is created, additional fluid containing proppant is used to transport these solid particles into the fractures. Then, the hydraulic pressure is released and the fracture will tend to close. At that stage, the proppant prevents fracture closure and provides a conductive channel for hydrocarbons to flow into the wellbore. Biopolymers, synthetic polymers, foams, viscoelastic surfactant (VES) fluids, and slickwater are all used as fracturing fluids, each with properties that are beneficial under certain conditions. Today, their formulations are well-developed, and more recently, may incorporate small-sized particles in the nanometer size range. Such nanoparticles have addressed certain technological limitations of fracturing fluids. For example, VES fluids were reported to suffer high leakoff rates in moderate permeability reservoirs (200 md) and were limited in temperature (beyond approximately 220°F, viscosity was diminished significantly). Another challenge is the pressure-dependent behavior of borate-crosslinked gels, where the viscosity was found to drop significantly under high pressures. Also, in high-temperature reservoirs (>350°F), it is very challenging to design a fluid that can sustain enough viscosity for a required period of time. Synthetic polymers (mainly acrylamide-based polymers) are commonly used and have been reported to be used at high concentrations. These high-concentration requirements are imposed by the need for a stable viscosity under high-temperature conditions. High polymer loading increases the potential of formation damage caused by the fluid residue. These challenges, which can be addressed by nanotechnology, could have a major impact on hydraulic-fracturing applications. For instance, the working temperature limit of VES-based fluids was improved from 200 to 250°F (93 to 121°C) by adding zinc oxide (ZnO) and magnesium oxide (MgO) nanoparticles. The borate-crosslinked gels were found to maintain their viscosity at pressures up to 20,000 psi when using boronic acid-functionalized nanolatex silica particles as crosslinkers, while under such high pressures, conventional borate crosslinkers showed more than 80% reduction in viscosity. Moreover, the rheological properties of mixed VES/polymer fluids were enhanced when using nanoparticles. Use of foams can reduce the amount of water consumed in hydraulic fracturing. Alfa olefin sulfonate (AOS) surfactant can be foamed by use of carbon dioxide (CO2). Aluminum oxide nanoparticles were found to stabilize the foams created by AOS, VES, and CO2. This has a potential application in waterless fracturing. This review paper will capture all of these aspects and summarize the most recent experience of nanoparticle usage in hydraulic-fracturing fluids design.
Photoperiod, Irradiance, and Temperature Affect Echinopsis ‘Rose Quartz’ Flowering
Authors: Erwin John , O’Connell Rene , Altman Ken
Published: January 2017

Photoperiod, irradiance, cool temperature (5 °C), and benzyladenine (BA) application effects on Echinopsis ‘Rose Quartz’ flowering were examined. Plants were placed in a 5 °C greenhouse under natural daylight (DL) for 0, 4, 8, or 12 weeks, then moved to a 22/18 °C (day/night temperature) greenhouse under short days (SD, 8-hour DL) plus 0, 25, 45, or 75 μmol·m−2·s−1 supplemental lighting (0800–1600 hr; 8-hour photoperiod), long days (LD) delivered with DL plus night-interruption lighting (NI) (2200–0200 hr), or DL plus 25, 45, or 75 μmol·m−2·s−1 supplemental lighting (0800–0200 hr) for 6 weeks. Plants were then grown under DL only. Percent flowering plants increased as irradiance increased from 0–25 to +75 μmol·m−2·s−1 on uncooled plants, from 0% to 100% as 5 °C exposure increased from 0 to 8 weeks under subsequent SD and from 25% to 100% as 5 °C exposure increased from 0 to 4 weeks under subsequent LD. As 5 °C exposure duration increased from 0 to 12 weeks (SD-grown) and from 0 to 8 weeks (LD-grown), flower number increased from 0 to 11 and from 5 to 21 flowers per plant across irradiance treatments, respectively. Total production time ranged from 123 to 147 days on plants cooled from 8 to 12 weeks (SD-grown) and from 52 to 94 days on plants cooled for 0–4 weeks to 119–153 days on plants cooled for 8–12 weeks (LD-grown). Flower life varied from 1 to 3 days. BA spray application (10–40 mg·L−1) once or twice after a 12-week 5 °C exposure reduced flower number. Flower development was not photoperiodic. High flower number (17–21 flowers/plant) and short production time (including cooling time, 120–122 days) occurred when plants were grown at 5 °C for 8 weeks, then grown under LD + 45–75 μmol·m−2·s−1 for 6 weeks (16 hours; 10.9–12.8 mol·m−2·d−1) at a 22/18 °C day/night temperature. Taken together, Echinopsis ‘Rose Quartz’ exhibited a facultative cool temperature and facultative LD requirement for flowering.
Failure Analysis under Electric Lights: Growth and Yield of Sweetpotato in Response to 14 Days of Prolonged Darkness
Authors: Mortley Desmond G. , Hileman Douglas R. , Bonsi Conrad K. , Hill Walter A. , Morris Carlton E.
Published: January 2017

Two sweetpotato [Ipomoea batatas (L.) Lam] genotypes (TU-82-155 and NCC-58) were grown hydroponically and subjected to a temporary loss of lighting in the form of 14 days of prolonged darkness compared with a lighted control under standard daily light periods to determine the impact on growth responses and storage root yield. Vine cuttings of both genotypes were grown in rectangular channels. At 65 days after planting, lights were turned off in the treatment chambers and replaced by a single incandescent lamp, providing between 7 and 10 µmol·m−2·s−1 photosynthetic photon flux (PPF) for 18 hours, and the temperature lowered from 28/22 °C light/dark, to a constant 20 °C. Plants remained under these conditions for 14 days after which the original light level was restored. Growth chamber conditions predark included, a PPF mean provided by 400-W metal halide lamps, of 600 ± 25 µmol·m−2·s−1, an 18-hour light/6-hour dark cycle and a relative humidity of 70% ± 5%. The nutrient solution used was a modified half-Hoagland with pH and electrical conductivity (EC) maintained between 5.5–6.0 and 1000–1200 μS·cm−1, respectively, and was adjusted weekly. Storage root number and fresh weight were similar regardless of treatments. Plants exposed to prolonged darkness produced 10.5% and 25% lower fibrous root fresh and dry mass, respectively, but similar foliage yield and harvest index (HI). ‘NCC-58’ produced an average of 31% greater storage root yield than that of ‘TU-82-155’ but the number of storage roots as well as % dry matter (%DM) were similar. ‘NCC-58’ also produced 31% greater fibrous root dry weight, whereas ‘TU-82-155’ produced a 44% greater HI. The significant interaction between prolonged darkness and cultivars for %DM of the storage roots showed that DM for ‘TU-82-155’ was 18.4% under prolonged darkness and 17.9% in the light. That for ‘NCC-58’ was 16.4% under prolonged darkness compared with 19.4% (14.8% greater) for plants that were not subjected to prolonged darkness. The evidence that there were no adverse impacts on storage root yield following the exposure to prolonged darkness suggests that the detrimental effects were below the detectable limits for these cultivars in response to the short perturbation in the available light and that sweetpotatoes would be hardy under short-term failure situations.
Biological Characteristics and Vegetative Propagation of a New Camellia Cultivar Maozi
Authors: Wei Xiao-Juan , Liang Xiao-Jing , Ma Jin-Lin , Li Kai-Xiang , Liang Haiying
Published: January 2017

Camellia flowers are highly prized for their beauty worldwide and are strongly symbolic in many cultures. A new interspecific hybrid cultivar, Camellia ‘Maozi’, generated by crossing Camellia pubipetala with C. japonica ‘Dahong Mudan’, exhibits strong hybrid vigor and has small flowers with a rare light tone of purple. In southwest China with a subtropical monsoon climate, young Camellia ‘Maozi’ trees flush shoots three times in spring, summer, and autumn, with an average annual growth of 12.9 cm. Adult trees flush once a year. Floral bud formation occurs in late April and early May. Camellia ‘Maozi’ flowers are sterile with no fruits and seeds produced. While an individual flower wilts 4–8 days after opening, the blossom can last 1–3 months. Frost damage can be found in young leaves when temperature drops to 4–7 °C. Under direct sunlight with temperatures of 37–39 °C lasting for more than 2 days, young leaves can turn yellow on their edges. Its primary diseases include sooty mold, shoot tip blight, and peony leaf tip blight. Its primary insect pests are tea green leafhopper (Jacobiasca formosana) and tea aphid (Toxoptera aurantii). Rooting of stem cuttings occurs directly from stems, mostly without callus development. Two hours of treatment with 500 mg·L−1 indole-3-butyric acid and rooting in a mix of latosolic red soil and vermiculite (2:1 v/v) resulted in high rooting rate and quality of aboveground growth. Grafting can be carried out from May to September, while survival rate and new shoot length are highest in July. The most compatible rootstock is C. oleifera, followed by C. polyodonta. The results of this study are of value for understanding the reproductive biology of Camellia ‘Maozi’ and further disseminating it as a new cultivar for camellia collection.
Evaluating Calibrachoa (Calibrachoa ×hybrida Cerv.) Genotype Sensitivity to Iron Deficiency at High Substrate pH
Authors: Dickson Ryan W. , Fisher Paul R. , Padhye Sonali R. , Argo William R.
Published: January 2017

Floriculture crop species that are inefficient at iron uptake are susceptible to developing iron deficiency symptoms in container production at high substrate pH. The objective of this study was to compare genotypes of iron-inefficient calibrachoa (Calibrachoa ×hybrid Cerv.) in terms of their susceptibility to showing iron deficiency symptoms when grown at high vs. low substrate pH. In a greenhouse factorial experiment, 24 genotypes of calibrachoa were grown in peat:perlite substrate at low pH (5.4) and high pH (7.1). Shoot dry weight, leaf SPAD chlorophyll index, flower index value, and shoot iron concentration were measured after 13 weeks at each substrate pH level. Of the 24 genotypes, analysis of variance (ANOVA) found that 19 genotypes had lower SPAD and 18 genotypes had reduced shoot dry weight at high substrate pH compared with SPAD and dry weight at low substrate pH. High substrate pH had less effect on flower index and shoot iron concentration than the pH effect on SPAD or shoot dry weight. No visual symptoms of iron deficiency were observed at low substrate pH. Genotypes were separated into three groups using k-means cluster analysis, based on the four measured variables (SPAD, dry weight, flower index, and iron concentration in shoot tissue). These four variables were each expressed as the percent reduction in measured responses at high vs. low substrate pH. Greater percent reduction values indicated increased sensitivity of genotypes to high substrate pH. The three clusters, which about represented high, medium, or low sensitivity to high substrate pH, averaged 59.7%, 42.8%, and 25.2% reduction in SPAD, 47.7%, 51.0%, and 39.5% reduction in shoot dry weight, and 32.2%, 9.2%, and 27.7% reduction in shoot iron, respectively. Flowering was not different between clusters when tested with ANOVA. The least pH-sensitive cluster included all four genotypes in the breeding series ‘Calipetite’. ‘Calipetite’ also had low shoot dry weight at low substrate pH, indicating low overall vigor. There were no differences between clusters in terms of their effect on substrate pH, which is one potential plant iron-efficiency mechanism in response to low iron availability. This experiment demonstrated an experimental and statistical approach for plant breeders to test sensitivity to substrate pH for iron-inefficient floriculture species.
Short-term Effects of Composted Cattle Manure or Cotton Burr on Growth, Physiology, and Phytochemical of Spinach
Authors: Xu Chenping , Mou Beiquan
Published: January 2017

Compost is increasingly used in horticultural crop production as soil conditioner and fertilizer because of its contribution to agriculture sustainability. The short-term (35 days after transplanting) effects of composted cattle manure or cotton burr on growth, physiology, and phytochemical of spinach (Spinacia oleracea L.) were evaluated in a greenhouse. Composted cattle manure at 5% or 10% mix rate (5Ca or 10Ca) greatly enhanced spinach growth as indicated by increased leaf number, area, fresh and dry weights (FW and DW), shoot FW and DW, and root DW. They also increased water use efficiency (WUE) and shoot:root ratio, and improved the photochemistry of mature leaves. Chlorophyll content also increased under 10Ca treatment. Composted cotton burr also improved spinach growth but only at 10% amendments (10Co), and was less efficient than composted cattle manure. Specific leaf area (SLA) decreased and succulence increased under all compost amendment indicating that compost could improve spinach quality. All soil amendments reduced the content of total phenolic and anthocyanin, while only 10Co and 5Ca treatments decreased flavonoid content and total antioxidant capacity. The content of carotenoid and protein increased in 10Ca treatment and amino acid content increased under both 5Ca and 10Ca treatments. The results indicated that compost, especially composted cattle manure mixed at 10%, improved spinach production and quality, and with proper application rate enhanced nutritional value by increasing carotenoid, protein, and amino acid contents while having little effect on total antioxidant capacity.
Potassium Nitrate Alters Buffalograss Bur Permeability
Authors: Kreuser Katherine , Kreuser William C. , Sarath Gautam , Amundsen Keenan L.
Published: January 2017

Buffalograss is a warm-season, dioecious grass species yielding burs, which are routinely used for field plantings. The pistillate plants bear the burs containing 1–5 caryopses. Isolated caryopses readily germinate, but caryopses contained within burs exhibit strong dormancy, suggesting that burs inhibit germination. Priming burs with low concentrations of potassium nitrate (KNO3) is used as an industry standard to improve germination. Seed dormancy and germination in many species are strongly influenced by endogenous hormone levels, principally abscisic acid (ABA) and gibberellic acid (GA). It follows that buffalograss seed dormancy might be induced or overcome by altering the ratio of ABA to GA. The objectives of this research were 1) to contrast the effects of priming with KNO3 or water on bur germination, 2) to study how these treatments affected hormone profiles, specifically the ABA/GA ratios in the burs, and 3) to quantify treatment effects on the water permeability of the burs. Hormone profiles were analyzed following four postharvest seed-soaking treatments (24-hour 0.05 m KNO3, 24-hour H2O, 48-hour 0.05 m KNO3, and 48-hour H2O). Water infiltration tests on nontreated, 24-hour H2O-treated, and 24-hour 0.05 m KNO3-treated seeds were also conducted. Inconclusive hormone profiling results did not support the hypothesis that KNO3 postharvest treatment raises GA levels to encourage germination. Instead, our data support changes in seed morphology following KNO3 postharvest seed treatments which alter water permeability of the seedcoat leading to increased germination.
A Comparative Study on Antioxidant Potential of Selected African and Exotic Leafy Vegetables
Authors: Tesfay Samson Zeray , Mathe Sakhile , Modi Albert T. , Mabhaudhi Tafadzwanashe
Published: January 2017

African leafy vegetables (ALVs) are thought to contain an immense variety of antioxidants, which may provide nutritional and health benefits. However, there is limited, robust, and comparable information describing their nutritional composition. The aim of this study is to determine the antioxidant potential of selected ALVs [black jack (Bidens pilosa L.) and amaranth (Amaranthus hybridus L.)] in comparison with exotic leafy vegetables (ELVs) [lettuce (Lactuca sativa L.), green cabbage (Brassica oleracea), red cabbage (B. oleracea var. capitata)]. Different nonenzymatic and enzymatic antioxidant assays were used to determine plant carbohydrates (CHOs) using high-performance liquid chromatography (HPLC), phenols (Folin–Ciocalteu), ascorbic acid, carotenoids, total antioxidant capacity (TAOC) using reducing ferric ion antioxidant potential (FRAP) and 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) assays, super oxide dismutase (SOD), catalase (CAT), and peroxidase (POD). Both amaranth and black jack produced high levels of CHOs, carotenoids, ascorbic acid, and phenols during early vegetative growth [4 weeks after transplanting (WAT)]. Similarly, SOD, CAT, and POD activity for amaranth and black jack also increased during early vegetative development. Conversely, exotic vegetables (lettuce and cabbages) only increased these antioxidants toward maturity. Overall, ALVs have produced higher concentrations of antioxidants specifically during early vegetative growth stage than the exotic vegetables. The promotion of ALVs could promote a healthy alternative especially in poor rural households.
Sweet Onion (Allium cepa) Plant Growth and Bulb Yield and Quality as Affected by Potassium and Sulfur Fertilization Rates
Authors: Díaz-Pérez Juan Carlos , Bautista Jesús , Bateman Anthony , Gunawati Guna , Riner Cliff
Published: January 2017

‘Vidalia’ onions are sweet, short day, low pungency, yellow Granex-type bulbs that are popular in the United States. The relationships of sweet onion bulb yield and quality with potassium (K) and sulfur (S) concentrations are not fully understood. The objective of this study was to evaluate the effects of K and S fertilization rates on sweet onion plant growth and bulb yield and quality. Experiments were conducted at the Horticulture Farm, Tifton Campus, University of Georgia, in the Winters of 2012–13 and 2013–14. The experiment had five treatments (K/S rates: 56/80, 112/126, 168/172, 224/218, and 280/264 kg·ha−1 of K and S, respectively). K/S rates had no effect on onion biomass of roots, bulbs, and shoots during the growing season. Marketable and total number and weight of onion bulbs and individual bulb weight were also unaffected by K/S rate. Incidences of bolting, double bulbs, Botrytis leaf blight (Botrytis cinerea), and sour skin (Burkholderia cepacia), and bulb dry weight, soluble solids content (SSC), and pungency (pyruvate concentration) were unaffected by K/S rates. In conclusion, K/S rates had little effect on plant growth and bulb yield and quality. The lack of response of onion plants to K/S rates, even at the lowest rate suggests that some of the K absorbed by plants originated from K already present in the soil before planting. The average K content of sweet onion whole plants was 80 kg·ha−1 K. Thus, under our experimental conditions, application of K rates above the recommended value (84 kg·ha−1 K) are unnecessary and will likely not improve plant growth, yield, or quality. Regarding S, rates higher than 80 kg·ha−1 S are probably unnecessary and will not enhance either plant growth or bulb yield or quality of sweet onion.
The Effects of Postharvest Hot Water and Fungicide Treatments on Guignardia citricarpa Growth and the Development of Citrus Black Spot Symptoms on ‘Valencia’ Orange Fruit
Authors: Yan Jiaqi , Dewdney Megan M. , Roberts Pamela D. , Ritenour Mark A.
Published: January 2017

Citrus black spot (CBS), caused by Guignardia citricarpa, is a fungal disease that was first described in Australia in the 1890s and has since been discovered in Southwest Florida in 2010. The current study evaluated the effects of hot water treatments on mycelial growth of G. citricarpa in vitro and also evaluated postharvest hot-water dips and fungicide treatments on CBS development on ‘Valencia’ oranges. In vitro exposure to 56 °C for 120 seconds, 59 °C for 60 seconds, or 62 °C for 30 seconds suppressed mycelial growth of all three G. citricarpa isolates by >30%. These treatments did not significantly reduce disease incidence or severity of CBS lesion development on whole ‘Valencia’ oranges from CBS-infected trees when the fruit already had visible CBS symptoms before treatment. On asymptomatic fruit, while the treatments did not significantly reduce the incidence of CBS lesion development, fruit dipped in 56 °C water for 120 seconds significantly reduced disease severity after 2 weeks of storage compared with the control. None of the treatments caused peel scalding or fruit quality deterioration. Postharvest application of azoxystrobin, imazalil, or thiabendazole significantly reduced CBS disease severity on fruit that were asymptomatic at harvest, but did not affect disease incidence. These fungicides were not effective on fruit harvested later in the season (April), possibly because most lesion expression had already occurred before harvest, with little left to develop after harvest. On fruit showing CBS symptoms at harvest, postharvest fungicide treatments did not significantly affect disease incidence or severity after storage. Heating the fungicide solutions did not significantly improve fungicide effectiveness. These results demonstrated that fungicide azoxystrobin, imazalil, or thiabendazole could reduce CBS severity, but not incidence, on orange fruit that are still asymptomatic at harvest.
Variation in Carbohydrate Reserves and Dry Matter Production of Bush Tea (Athrixia phylicoides) Grown under Different Environmental Conditions
Authors: Mudau Fhatuwani N. , Mudau Ambani R. , Nkomo Mpumelelo , Ngezimana Wonder
Published: January 2017

Reserve carbohydrates are critical for herbage yields, productivity as well as management strategies of bush tea (Athrixia phylicoides DC). This study was conducted to evaluate carbohydrate accumulation in response to pruning seasons (summer, autumn, winter, and spring) involving different organs grown under different conditions and to determine mean dry matter production of bush tea. Three separate parallel trials were conducted under wild, field, and glasshouse conditions. Seasons and different growing sites were considered as treatments. Treatments for all controlled trials (field and glasshouse) consisted of seasonal pruning (winter, spring, summer, and autumn). Trials were arranged using a randomized complete block design with 25 single plants as replicates per treatment. Seasonal responses revealed that winter had the highest starch (145.0 mg·g−1) in the stems and reserve carbohydrates (480.6 mg·g−1) in the roots, whereas in the roots sugar (400.6 mg·g−1) was highest in summer. The highest significant root reserve carbohydrates occurred in winter (594.6 mg·g−1) and the lowest in autumn (fall) (313.3 mg·g−1). Bush tea plants pruned during winter had the highest overall reserve carbohydrates in the stem (598.7 mg·g−1). Under glasshouse conditions, the highest dry matter production was observed in December (midsummer) (170 g per plant); while in field-grown plants in the same month dry matter production was 400 g per plant. Therefore, the best time to maximize production of bush tea is during the spring and summer seasons.
Redundancies and Genetic Structure among ex situ Apple Collections in Norway Examined with Microsatellite Markers
Authors: Gasi Fuad , Kanlić Kenan , Stroil Belma Kalamujić , Pojskić Naris , Asdal Åsmund , Rasmussen Morten , Kaiser Clive , Meland Mekjell
Published: January 2017

Apple genetic resources in Norway are currently conserved within a number of local clonal archives. However, during establishment of these ex situ collections, primary focus was not on capturing as much of the diversity as possible, but instead on preserving cultivars of particular importance to specific fruit-growing areas. To identify redundancies within the collection as well as to assess the genetic diversity and structure of apple germplasm currently being conserved in Norway, eight microsatellites were used in genetic characterization of 181 apple accessions. Overall, 14 cases of synonym or possibly mislabeled accessions were identified, as well as several homonyms and duplicates within and among the analyzed collections. The information obtained should contribute to overall better management of the preserved germplasm. Bayesian analysis of genetic structure revealed two major clusters, one containing most of the foreign cultivars, while the other consisted mainly of traditional Scandinavian cultivars, but also some very winter-hardy genotypes such as ‘Charlamovsky’, ‘Gravenstein’, ‘Transparente Blanche’, and ‘Wealthy’. Analyses of molecular variance (AMOVA) detected a significant genetic differentiation among the clusters (fCT = 0.077; P < 0.01). The results of the Bayesian analyses do not indicate a strong differentiation between the foreign and the Norwegian apple accessions, however, they do suggest that climate adaptation has had a significant influence on the genetic structure of the preserved germplasm. Overall, apple accessions currently maintained ex situ in Norway represent a diverse germplasm which could be very valuable in future breeding programs, especially for the Scandinavian climate.
Impacts of Pre- and Postbloom Sprays of Tryptophan on Calcium Distribution within ‘Red Jonaprince’ Apple Trees and on Fruit Quality
Authors: Wójcik Paweł , Skorupińska Anna , Gubbuk Hamide
Published: January 2017

The aim of this study was to examine the effects of tryptophan (L-TRP) sprays on calcium (Ca) distribution within mature ‘Red Jonaprince’ apple (Malus domestica Borkh.) trees and on fruit quality. Trees were sprayed with L-TRP before flowering (at the green and pink bud stages and when 5% to 10% of flowers were open), after flowering (at petal fall and 14 and 28 days later), and both before and after flowering. In each spray treatment, 50 g of L-TRP per ha was applied. Other trees were sprayed with calcium chloride (CaCl2) six times during the growing season at rates ranging from 6 to 9 kg⋅ha−1. Plants that were not sprayed with L-TRP or CaCl2 served as controls. The results found that the studied spray treatments did not affect yield, mean fruit weight, apple skin russeting and blush, seed set, mean seed weight, or acidity of fruit at harvest. Prebloom L-TRP sprays enhanced the concentrations of both free indole-3-acetic acid (IAA) in fruitlets (by ≈230% compared with those of the control plants) and Ca in fruitlets and fruit (on average by 18% compared with the control combination) but did not affect the leaf Ca concentrations. Apples from trees sprayed with L-TRP before flowering had lower starch index (SI) values at harvest than those of the control plants. Postbloom L-TRP sprays increased leaf Ca concentration, but had no effect on apple Ca concentration or fruit quality at harvest. Combined pre- and postbloom L-TRP sprays did not improve the effectiveness of this amino acid. Overall, preharvest CaCl2 sprays increased leaf and fruit Ca concentrations and decreased fruit SI. Apples sprayed with CaCl2 had lower soluble solids concentrations (SSCs) and were firmer than fruit from control trees. Prebloom L-TRP sprays are effective in improving apple Ca concentration, at least for triploid varieties that have small seed numbers.
Concentration and Timing of Ethephon Drench Applications Interact to Affect Growth and Flowering of Containerized Angelonia and Geranium
Authors: Currey Christopher J. , McCabe Kenneth G. , Walters Kellie J.
Published: January 2017

Ethephon drenches have been reported to effectively control growth of containerized bedding plants. However, previous researchers have indicated that the effects of ethephon drenches on growth and flowering may differ depending on the timing of applications. Our objectives were to quantify the effects of ethephon concentration, timing of substrate drench application, and their interaction on the growth, size, and flowering of two annual bedding plants. Angelonia (Angelonia angustifolia) and geranium (Pelargonium ×hortorum), seedlings were planted in 10.2-cm-diameter containers filled with a commercial, soilless growing substrate composed of (by vol.) 75% sphagnum peatmoss, and 25% perlite. Five, 10, 15, or 20 days after transplanting seedlings, 70-mL aliquots containing 0, 50, 100, or 200 mg·L−1 ethephon were applied as substrate drenches. Species varied in their growth and flowering responses to ethephon concentration, drench application timing, and their interaction. For angelonia, flowering was delayed most with early applications and high concentrations, and delay was diminished with later applications. Angelonia height was unaffected by late applications, though lateral growth was suppressed 20 days after transplant with 200 mg·L−1 ethephon. Flowering of geranium was only delayed when ethephon was applied 5 days after transplanting, whereas flowering, vegetative height, and shoot dry weight were affected more by earlier applications and higher concentrations. Width and root weight were only affected by ethephon concentration, with growth suppression increasing as concentrations increased. Ethephon is an effective growth regulator when applied as a substrate drench. However, the degree of activity and resulting impact on flowering, size, and growth is influenced by the interaction between ethephon concentrations and the timing of drench applications after transplanting.
Reduced Tillage Impacts on Pumpkin Yield, Weed Pressure, Soil Moisture, and Soil Erosion
Authors: O’Rourke Megan E. , Petersen Jessica
Published: January 2017

Conservation tillage has the potential to decrease the environmental footprint of pumpkin production, but possible trade-offs with yield are not well understood. This study experimentally tested the effects of three cultivation techniques (conventional-till, strip-till, and no-till) on pumpkin production, weed pressure, soil moisture, and soil erosion. Randomized complete block field experiments were conducted on Cucurbita pepo L. ‘Gladiator’ pumpkins in 2014 and 2015. Overall yields were higher in 2015, averaging 45.2 t·ha−1, compared with 37.4 t·ha−1 in 2014. In 2014, pumpkin yields were similar across tillage treatments. In 2015, the average fruit weight of no-till pumpkins was significantly greater than strip-till and conventional-till pumpkins, which corresponded to a marginally significant 13% and 22% yield increase, respectively (P = 0.11). Weed control was variable between years, especially in the strip-till treatment. Soil moisture was consistently highest in the no-till treatment in both years of study. Conventional-till pumpkin plots lost ≈9 times more soil than the two conservation tilled treatments during simulated storm events. The 2015 yield advantage of no-till pumpkins seems related to both high soil moisture retention and weed control. Research results suggest that no-till and strip-till pumpkin production systems yield at least as well as conventional-till systems with the advantage of reducing soil erosion during extreme rains.
Effect of Plant Species, Fertilizer Acidity/Basicity, and Fertilizer Concentration on pH of Soilless Root Substrate
Authors: Jeong Ka Yeon , Nelson Paul V. , Niedziela Carl E. , Dickey David A.
Published: January 2017

The objective of this study was to determine how plant species, fertilizer potential acidity/basicity rating (PABR), and fertilizer concentration affect root substrate pH. Three experiments were conducted. In the first experiment, 13 herbaceous species were grown in a root substrate of three sphagnum peatmoss: one perlite (v/v) with deionized water and a neutral fertilizer (NF) with a PABR of 0 for 78 days to determine species relationships to substrate pH. The decrease in substrate pH ranged from 0.14 to 2.45 units, depending on species. In the second experiment, four of the 13 species from the previous trial representing the range of pH suppression were grown under similar growth conditions as the first experiment for 70 days. Substrate pH was lowered in the range of 0.47 to 2.72 units. In the third experiment, three fertilizers with PABRs of 150 kg·t−1 CaCO3 equivalent alkalinity, 0 neutral, and 193 kg·t−1 CaCO3 equivalent acidity were applied in a factorial design at 100 and 200 mg·L−1 N at each irrigation to kalanchoe (the species with the greatest pH suppression from the previous experiments) for 56 days. When applied at the lower fertilizer rate (100 mg·L−1 N), the PABRs resulted in the final substrate pH levels of 4.68, 5.60, and 6.11 for the acidic fertilizer (AF), NF, and basic fertilizer (BF), respectively. At the high fertilizer rate (200 mg·L−1 N), substrate pH declined continuously to 3.97, 4.03, and 4.92 for the AF, NF, and BF, respectively. Expression of PABR depended on the balance between the abiotic (chemical) effect of the fertilizers vs. the biotic (physiological) effects of the fertilizers on microbes and plants. The PABR was best expressed when the fertilizer supply was just adequate or lower indicating a closer connection to the biotic effect.
Sensory Attributes of Juice from North American–Grown Elderberry Cultivars
Authors: Warmund Michele , Kwasniewski Misha , Elmore Janelle , Thomas Andrew , Adhikari Koushik
Published: January 2017

Various elderberry (Sambucus sp.) cultivars, including Bob Gordon, Marge, Ocoee, Ozark, Wyldewood, and York, have been selected primarily for plant productivity in North America and are most often processed into juice-based products. This study was conducted to quantify juice characteristics and to evaluate sensory attributes of juice from six elderberry cultivars using descriptive analysis. Hue angle values of ‘Bob Gordon’ and ‘York’ juices were low as compared with others tested. Soluble solids and titratable acidity of juices from ‘Wyldewood’ and ‘York’ were lower than those from other cultivars. Trained panelists identified 24 terms for descriptive analysis of elderberry juices. Of these 24 attributes, juices were highly characterized by a processed aroma, and several flavors, including processed, elderberry, fruity, and sweet. Unique juice descriptors for North American–grown elderberry cultivars included apple, beet, caramelized, fermented, processed, and pomegranate flavors, as well as astringent mouthfeel. Juices from elderberry cultivars differed in intensity ratings of nine attributes, including fruity, floral, sweet aromatics, bitter, sour, and sweet flavors, bitter and sweet aftertastes, and astringent mouthfeel. ‘York’ juice generally had high intensity ratings for sweet aromatics and sweet flavors, and relatively lower ratings for bitter aftertaste and astringent mouthfeel as compared with juices from other cultivars. This study provided key elements for future elderberry sensory research in the development of a formal lexicon for juice with defined attributes.
Mechanical Harvesting and Postharvest Storage of Two Southern Highbush Blueberry Cultivars Grafted onto Vaccinium arboreum Rootstocks
Authors: Casamali Bruno , Williamson Jeffrey G. , Kovaleski Alisson P. , Sargent Steven A. , Darnell Rebecca L.
Published: January 2017

The profitability of the fresh market blueberry industry in many areas is constrained by the extensive use and cost of soil amendments, high labor requirements for hand harvesting, and the inefficiencies of mechanical harvesters. Vaccinium arboreum Marsh is a wild species that has wide soil adaptation and monopodial growth habit. It has the potential to be used as a blueberry rootstock, expanding blueberry production to marginal soil and improving the mechanical harvesting efficiency of cultivated blueberry. The objectives of this research were to compare yield, berry quality, and postharvest fruit storage of own-rooted vs. grafted southern highbush blueberry (SHB) cultivars (Farthing and Meadowlark) grown on amended vs. nonamended soil and either hand or mechanical harvested. Yields of hand-harvested SHB during the first two fruiting years were generally greater in own-rooted plants grown on amended soil compared with own-rooted plants on nonamended soil or grafted plants on either soil treatment. However, by the second fruiting year, hand-harvest yields of grafted SHB were ≈80% greater than own-rooted plants when grown in nonamended soil. Yields of mechanical-harvested SHB grafted on V. arboreum and grown in either soil treatment were similar to yields of mechanical-harvested own-rooted plants in amended soil the second fruiting year, and greater than yields of own-rooted plants in non-amended soil. In general, mechanical harvesting reduced marketable yield ≈40% compared with hand harvesting. However, grafted plants reduced ground losses during harvest by ≈35% compared with own-rooted plants for both cultivars. Mechanical-harvested berries had a greater total soluble solids:total titratable acidity ratio (TSS:TTA) than hand-harvested berries, and berries harvested toward the end of the harvest season had a greater TSS:TTA than those from early-season harvests. As postharvest storage time increased, berry appearance ratings decreased and berry softness and shriveling increased, particularly in mechanical-harvested compared with hand-harvested berries. Firmness of mechanical-harvested berries decreased during storage, whereas firmness of hand-harvested berries remained relatively stable. However, fruit quality at harvest and during postharvest storage was unaffected by V. arboreum rootstocks or lack of pine bark amendment. This study suggests that using V. arboreum as a rootstock in an alternative blueberry production system has the potential to decrease the use of soil amendments and increase mechanical harvesting efficiency.
In Vitro Chromosome Doubling of Prunus laurocerasus ‘Otto Luyken’ and ‘Schipkaensis’
Authors: Contreras Ryan N. , Meneghelli Luigi
Published: January 2017

Prunus laurocersaus L. (2n = 22x = 176), common cherrylaurel, is an evergreen shrub generally used as a hedge or screen. This species produces large drupes that are a nuisance when they drop on walkways or deposited by birds and also has escaped cultivation in parts of northwestern United States, which has raised concern about the invasive potential of common cherrylaurel. Therefore, a fruitless and sterile form of common cherrylaurel is desirable. As part of our efforts to develop sterile common cherrylaurel cultivars, we conducted two experiments to induce chromosome doubling using in vitro exposure of ‘Otto Luyken’ and ‘Schipkaensis’ cherrylaurel to oryzalin. For ‘Otto Luyken’ (Expt. 1), we tested the effects of treatment duration (1, 2, 14, or 28 days) and oryzalin concentration (0, 6.25, 12.5, 25, 50, 100, or 150 μm) applied in a liquid phase over explants. In Expt. 2, we treated ‘Schipkaensis’ cherrylaurel shoots with a single duration of 28 days and exposed explants to the same varying concentrations of oryzalin incorporated into the solidified medium. In Expt. 1, the 14-day treatment had reduced survival compared with 1- and 2-day treatments and there was still greater mortality in the 28-day treatment. Duration of the treatment affected mortality more than oryzalin concentration. Sixteen treatment combinations resulted in 44x plants. The percentage of 44x plants increased with concentration in the 1- and 2-day treatments up to 30% of treated shoots at 150 μm. Overall, the longer duration treatments in Expt. 1 were less efficient for inducing 44x plants. Expt. 2 was less effective for inducing homogenous 44x plants. It is unclear if this is due to treatment or cultivar differences but the highest concentration was 8% in the 6.25 μm treatment.
Nitrogen Dynamics of Cole Crop Production: Implications for Fertility Management and Environmental Protection
Authors: Smith Richard , Cahn Michael , Hartz Timothy , Love Patricia , Farrara Barry
Published: January 2017

Intensive production of cool-season vegetables has contributed to nitrate pollution of groundwater along the central coast of California. Broccoli (Brassica oleracea L. var. italica), cabbage (Brassica oleracea L. var. capitata), and cauliflower (Brassica oleracea L. var. botrytis) are important crops in this region, but few data are available regarding the nitrogen dynamics of these cole crops under current production practices, and whether those practices are protective of groundwater. Monitoring was conducted in 14 commercial broccoli, 8 cabbage, and 8 cauliflower fields evaluating crop growth, rooting depth, N uptake and partitioning, patterns of soil N availability, and current N fertilization and irrigation practices. Aboveground biomass N at harvest averaged 367, 367, and 319 kg·ha−1 for broccoli, cabbage, and cauliflower, respectively, with mean N fertilization rates of 209, 280, and 256 kg·ha−1. The relatively small fraction of biomass N removed at harvest with cauliflower (23%) and broccoli (31%) resulted in a low partial N balance (PNB) of 30% and 57%, respectively, compared with cabbage (PNB of 70%). Rooting depth increased throughout the growing season, reaching ≈1 m by harvest, with about 70% of roots located in the top 40 cm in all crops. Soil mineral N (SMN; 0- to 30-cm depth) varied among fields, with the early-season median value of 18 mg·kg−1 declining to 5 mg·kg−1 by harvest. Seasonal N application was not correlated with early-season SMN. Irrigation applied, predominately through sprinklers, averaged >200% of estimated crop evapotranspiration. Substantial N mineralization from broccoli residue was observed within 2–3 months following fall incorporation, with potential NO3-N leaching losses exceeding 100 kg·ha−1 in both monitored fields. We conclude that improved irrigation management, adjusting N rates based on residual SMN, and employing a remediation practice such as cover cropping to limit winter NO3-N leaching losses could substantially improve N efficiency in cole crop production.
Introduction and Evaluation of Tomato Germplasm by Participatory Mother and Baby Trials in the Morogoro Region of Tanzania
Authors: Testen Anna L. , Mamiro Delphina P. , Mtui Hosea D. , Nahson Jackson , Mbega Ernest R. , Francis David M. , Miller Sally A.
Published: January 2017

Tomato is an important cash crop in many developing countries. However, smallholder farmers often lack access to improved cultivars and breeding programs to develop locally adapted cultivars are limited. Participatory crop improvement (PCI) approaches can be used to increase farmer access to improved cultivars. In this project, we used the mother and baby trial (MBT) design to introduce and evaluate tomato cultivars in three villages in the Morogoro Region of Tanzania. Mother trials were conducted in seven environments within the three villages, and variance partitioning revealed significant genetic effects for all traits measured with h2 ranging from 0.74 to 0.90 for yield and disease reaction, respectively. In baby trials, farmers provided qualitative rankings of cultivars for 16 characteristics, including vigor, yield, harvest period, diseases, insect damage, fruit quality, and salability. Results from baby trials indicated that introduced cultivars were locally acceptable to farmers, except for traits related to marketability. Outcome Mapping was used to evaluate progress in each of the three villages and results suggested that high stakeholder participation levels could predict future adoption of introduced cultivars. Our findings provide a framework for evaluating, selecting, and breeding tomato and other horticultural crops in developing countries using the MBT design for PCI.