bluuebunny/crossref_metadata_2025 huggingface dataset:
Combining Physics, Statistics and Heuristics in the Decline Curve Analysis of Large Datasets in Unconventional Reservoirs
Authors: Holanda Rafael Wanderley , Gildin Eduardo , Valkó Peter P.
Published: May 2017

Analytical single well models have been particularly useful in forecasting production rates and Estimated Ultimate Recovery (EUR) to the massive number of wells in unconventional reservoirs. In this work, a physics-based decline curve model accounting for linear flow and material balance in horizontal multi-stage hydraulically fractured wells is introduced. The main characteristics of pressure diffusion in the porous media and the fact that the reservoir is a limited resource are embedded in the functional form, such that there is a transition from transient to boundary dominated flow and the EUR is always finite. Analogously to the frequently used Arps hyperbolic, the new model has only three parameters, where two of them define the decline profile and the third one is a multiplier.

This model is applied to a large dataset in a workflow that incorporates heuristic knowledge into the history matching and uncertainty quantification by assigning weights to rate measurements. The heuristic rules aim to lessen the effects of non-reservoir related variations in the production data (e.g. temporary shut-in due to fracturing in a neighboring well) and emphasize the reservoir dynamics to perform reliable predictions. However, there are additional degrees of freedom in the way these rules define the values of the weights, therefore a criteria is established that "calibrates" the uncertainty in the probabilistic models by adjusting the parameters in the heuristic rules. Uncertainty quantification and calibration is performed via a Bayesian approach with hindcasts. This methodology is implemented in an automated framework and applied to 992 gas wells from the Barnett shale. A comparison with the Arps hyperbolic, Duong and stretched exponential models for this dataset shows that the new model is the most conservative in terms of estimated reserves.
Integrated Modeling of Formation Damage and Multiple Induced Hydraulic Fractures During Produced Water Reinjection
Authors: Fischer K. , Ferreira F. C. , Holzberg B. B. , Pastor J. S. , Reinli L. , Furuie R. , Vasconcelos D. M. , Dutra T. A.
Published: May 2017

During produced water reinjection into an oilfield, the formation near the wellbore is progressively damaged due to total suspended solids (TSS) and oil particles in the injected water (OIW). This typically increases the bottom-hole injection pressure over time. Furthermore, if the water is injected in the oil zone, the initial bottom-hole injection pressure may already be high from the start due to water mobility constraint and oil viscosity. This study aims to model the generation of hydraulic fractures induced under different conditions, their geometrical characteristics and corresponding development over time. Such information is key to reservoir simulation for the secondary oil recovery and to reservoir integrity assessment.

Four disciplines are integrated into the proposed workflow: reservoir flow simulation, formation damage modeling, reservoir geomechanics, and the simulation of hydraulic fracturing. First, a sector model around an injector well is extracted from the full-field reservoir simulation of the case-study reservoir. In the reservoir flow simulation, a formation damage model is implemented, calibrated from injection rate, bottom-hole pressure, TSS and OIW actual data. At specified time steps, the flow simulator passes pore pressure profiles of the sector model to the geomechanical simulator, which computes the corresponding changes in stress and deformation.

The updated in-situ stress field, in combination with the petrophysical model applied for the flow simulation, is provided to the hydraulic fracturing simulator, which tests for the development of the hydraulic fracture and computes its geometry. The resulting hydraulic fracture is mapped back into the reservoir flow model to account for the local increase of permeability of the cells hosting the fracture. The workflow then enters into a loop starting again with the flow simulation, and the further development of the fracture under changing conditions is tested and modeled.

The proposed workflow was successfully applied to an injection well in an offshore field. Four scenarios considered different initial formation saturation, injected fluid viscosity and the conversion of a producing well into an injector. Multiple fractures with different characteristics, fully contained inside the reservoir, were predicted for each scenario and gave insights into the hydraulic fracture development during produced water reinjection.

The proposed method and workflow have the potential to significantly improve the reservoir simulation of the water injection process for secondary recovery or pressure maintenance by providing insights into how induced fracture geometries will influence the injection pressure and reservoir sweep efficiency. It also may provide valuable information to assess the integrity of reservoir cap rock during produced water reinjection.
Models for Calculating Organic and Inorganic Porosities in Shale Oil Reservoirs
Authors: Piedrahita J. A. , Aguilera R.
Published: May 2017

The objective of this study is to present methods for calculating organic and inorganic porosities in shale oil reservoirs. This is achieved by combining density, neutron and NMR logs as well as laboratory geochemical and synthetic geochemical properties of organic matter. The study also presents methods for calculating these porosities when all the above data are not available. This is important as data scarcity is a common problem in most shale reservoirs.

Shales are generally composed by clays, inorganic matrix, organic matter and natural fractures. In this study, responses of density, neutron, and NMR logs are written in terms of properties of each shale component including clays, solid and porous volume for both inorganic (including natural fractures) and organic matter. Different analytical models are built depending on available input data and the approach used to convert weight total organic carbon (TOC) to TOC volume percentage. However, as is usually the case, the availability of different sources of information including geochemical data, routine and/or special core analysis will enhance the validity of the interpretation.

Models developed in this study indicate that organic porosity results (intrinsic and scaled to total volume) are very consistent with values measured in the laboratory and values reported in the literature. There are three approaches for converting weight TOC to percent volume TOC. Our results show that these three approaches have to be used carefully. Their indiscriminate use can lead to errors as the organic porosity is very sensitive to the TOC transformation. The organic porosity is also very sensitive to properties assumed for each component of the reservoir rock.

Depending on petrophysical and reservoir engineering needs, the organic porosity can be easily scaled to the volume of only the organic matter (intrinsic organic porosity) or to the bulk volume (total organic porosity) of the total system. In addition to organic porosity, the models developed in this study also allow calculating kerogen volume and its respective solid portion, allowing thus an estimate of solid kerogen and porosity within the kerogen material. Furthermore, the models also allow calculating inorganic porosity (matrix plus natural fractures).

Unlike current models that use separately conventional logs or NMR logs to calculate the porosity associated with organic matter, this study integrates all these logs as well as laboratory and synthetic geochemical properties of organic matter to develop new methods for estimating rigorously-scaled organic porosity.
Use of Dynamic Data for Estimating Average Reservoir Pressure, OGIP, and Optimum Well Spacing in Shale Gas Reservoirs
Authors: Orozco D. , Aguilera R.
Published: May 2017

The average reservoir pressure is a key parameter in material balance calculations, but its determination is challenging when dealing with shales because of their low and ultra-low permeabilities. This paper presents an easy-to-reproduce methodology for calculating the average reservoir pressure from flowing data, and its use in a new Material Balance Equation (MBE) that considers the simultaneous contribution of free, adsorbed and dissolved gas.

The procedure developed in this paper uses a modified gas compressibility factor (Z') introduced in the new MBE. Since Z' accounts for the combined effect of free, adsorbed and dissolved gas, then total original gas-in-place (OGIP) can be determined from extrapolation of the MBE straight line to an average reservoir pressure equal to zero. Drainage area can be estimated on the basis of the calculated OGIP and volumetric equations. As such, the methodology offers the potential to help improve well spacing in shale gas reservoirs in such a way that no stranded gas is left in the reservoir, or that not excess wells are drilled in the field. This can help to improve recoveries from shales by assisting in the determination of the optimum number of wells needed to drain efficiently a given play.

In conventional reservoirs, a well is shut-in and the average reservoir pressure is determined from the corresponding pressure build-up test. But, for the case of unconventional shale gas reservoirs, shutting the wells in is unacceptable due to the long time it would require for estimating average reservoir pressure. The methodology developed in this paper for shale gas reservoirs circumvents this problem by using dynamic data.

Production data from multi-stage hydraulically fractured horizontal wells completed in a Canadian shale gas reservoir are used for testing the effectiveness of the new methodology. Comparison of typical well spacing values vs. the drainage area calculated with the new methodology leads to the conclusion that, probably, only 40% of the gas is being drained efficiently.

The novelty of this work relies on the development of a methodology for calculating average reservoir pressure, OGIP, drainage area, and optimum well spacing in shale reservoirs through the combination of dynamic data and a new MBE that considers simultaneously the effects of free, adsorbed and dissolved gas.
An Overview of Deepwater Well Integrity Developments After the Blowout of Macondo
Authors: Santos O. L. , Ribeiro P. R.
Published: May 2017

Well integrity undeniably is considered one of the most important topics of the petroleum industry. Failure in not keeping a well integrity system functioning adequately may result in disastrous accidents called blowouts with all tragic consequences that they may bring: loss of human lives, loss of drilling equipment or production facilities, loss of hydrocarbon reserves and pollution. Also, well integrity issues may lead to substantial financial losses during the entire well life cycle as a result of non-productive operational time and/or remedial solutions. The situation is aggravated when considering deepwater scenarios.

Unfortunately, in 2010 the oil industry faced its worth accident caused by the loss of well integrity: the blowout of Macondo in the Gulf of Mexico with devastating consequences to the oil industry. The accident has been demanding from all players (operators, drilling contractors, service companies, regulators, industry organizations, academia and training providers) a huge amount of effort to minimize the risk of having this kind of accident repeated. Originally, those efforts were aimed at deepwater drilling activities in the Gulf of Mexico but with time they were disseminated throughout the oil industry activities all over the world.

Significant progress has been done to enhance the safety during all phases of the well life cycle since the Macondo blowout. This paper intends to present and discuss with actual examples the latest technical and managerial developments with emphasis in deepwater situations since the tragic blowout of Macondo happened. Particular attention is given to the following aspects: operational guidelines, regulations, well control equipment, training and competency assurance, well integrity management systems, novel technologies and research.
New Drill Pipe Size Improved Drilling Efficiency in Shale Plays
Authors: Lafuente M. , Granger S.
Published: May 2017

Drilling horizontal wells typically requires a tremendous engineering effort due to operational challenges with wellbore hydraulics, borehole cleaning, drill string buckling, poor weight-on-bit transfer, and reduced drill pipe service life. Typical symptoms include reduced rate of penetration, difficulty sliding, frequent wiper trips, excessive back-reaming, high torque/drag, and severe drill pipe wear coupled with potential connection damage.

In response to these industry needs, a new type of drill pipe optimized for shale drilling was developed. Modelling with several software packages was performed to compare this new 4-1/4" diameter Shale Drill Pipe (SDP) against conventional 4" diameter drill pipe in a typical 20,000 ft MD Bakken well. Three main areas of improvement were identified: hydraulics, buckling resistance, and reduced tube wear.

For one operator in Western Oklahoma, SDP provided a solution to some operational restrictions. The Operator elected to use the SDP primarily due to standpipe pressure limitations of the drilling rig (+/- 3,400 psi). The expectation was that SDP would improve performance in these wells, while still offering an economic alternative to other, more costly solutions such as using a more costly rig.

This paper will examine the field results of eight horizontal wells drilled in Western Oklahoma. The first three, which served as the baseline, were drilled to the planned total depth using a drill string with conventional 4" diameter drill pipe while the other five wells were drilled using the newly developed 4-1/4" diameter Shale Drill Pipe. Improvements in the drilling process observed with this new technology, particularly a reduction in stand pipe pressure, will be demonstrated. This innovative new design in drill string technology is one of the industry's first drill pipe based solutions addressing drilling challenges at a more fundamental level.
Non-Destructive Measurement of Porosity, Compressibility and Gas Sorption in Core Plugs from the Wolfcamp Shale
Authors: Tovar F. D. , Barrufet M. A. , Schechter D. S.
Published: May 2017

This work presents the carbon dioxide (CO2) storage capacity of the Wolfcamp formation in West Texas. The potential of CO2 for enhanced oil recovery from unconventional liquid reservoirs have been under investigation in recent years. Quantifying the rock ability to store CO2 is necessary for the economic assessment of CO2 EOR, and for the evaluation of carbon sequestration capacity. We measured the porosity, the rock compressibility and the CO2 sorption in sidewall core plugs taken from two wells drilled in the Wolfcamp shale. Computed tomography scanning technology was used to image the samples and investigate the relation between rock density and porosity, and rock density and CO2 sorption.

A gas expansion pycnometer was used for the experiments. To accommodate the challenges associated with extremely tight rocks the equipment was provided with accurate temperature control, and a high resolution gauge with the capability of recording pressure as a function of time. Porosity and compressibility were measured simultaneously using helium. We used different treatments for the rock compressibility and explored its behavior at low pressure. A Langmuir isotherm was used to account for sorption of CO2 on the organic matter of the shale. The volume available for free gas was corrected by incorporating the rock compressibility and the volume of the layer of sorbed CO2 in the analysis of the sorption data.

This study adds to the understanding of the storage capacity of the Wolfcamp shale. We found the porosity to be between 5.94 and 10.30%, the Langmuir volume between 38.77 and 154.51 scf/ton, and the Langmuir pressure from 512.59 to 1384.52 psig. Using CT number as a proxy for total organic content, we observed a linear relation between CT number and sorption capacity. Porosity also showed a linear relation with CT number. Free CO2 storage is the main storage mechanism, at pressures above 2500 psig (for all samples) accounting for more than 80 %. Sorption is a relevant storage mechanism at low reservoir pressure. Neglecting the rock compressibility or the volume of the sorbed layer can lead to wrong estimates of sorption capacity.

The techniques developed in this work provide for an economic and accurate mean of measuring porosity, compressibility, and sorption in tight unconventional core plugs. The use of a non-destructive approach is necessary to characterize core plugs that must remain intact for further testing such as the evaluation of enhanced recovery techniques in unconventional reservoirs. This research provides relevant data for the economic assessment of CO2 EOR in the Wolfcamp and the potential for carbon sequestration. The linear relations we observed for both, porosity and sorption capacity, with CT numbers, are of extreme interest as they can be exploited for faster petrophysical evaluation of unconventional tight rocks.
New Insight to Apply Azimuthal Geosteering
Authors: Cedeno D. , Alvarez A. , Fuentes J. , Portilla C. , Machare V. , Erazo R. , Escobar K. , Cedeño R. E.
Published: May 2017

This work highlights the use of tools that can perform multi-space directional multifrequency propagation measurements to drill horizontal wells in real time. The same that provide information such as the distance of the geological limits and the orientation of fluids through interpretations that can be executed in real time and recorded mode. The new concept of measurements and principles involves tilted and transverse antennas to provide measurements that are sensitive to the orientation of the tool with respect to the geological structure around the well, enhancing real time decision making and improving the geo-position trajectory of productive wells.
Methodology for Petrophysical and Geomechanical Analysis of Shale Plays. Case Study: La Luna and Capacho Formations, Maracaibo Basin.
Authors: Lobo C. , Molina A. , Faraco A. , Mendez J. , Delgadillo J. , Rincon G.
Published: May 2017

According to EIA (Kuuskraa et al., 2013) and PDVSA Exploration (Molina et al., 2014), the Maracaibo Basin in Western Venezuela has two stratigraphic units of Late Cretaceous age which are considered as important unconventional shale plays in Latin America: La Luna Formation and La Grita Member of Capacho Formation. Venezuela is ranked in 7t place in shale oil resources, with an estimate above 13,000 MM barrels, and ranked in 13th place in shale gas resources, with an estimate above 201 TCF. In order to evaluate the mentioned shale plays, a methodology was developed through the integration of petrophysical, geochemical and geomechanical analysis.

The complete evaluation methodology has 4 phases: 1) petrophysical evaluation, that includes multimineral evaluation, porosity estimation and calibration with mineralogical analysis; 2) TOC content evaluation, that includes TOC content estimation, using 3 methods: density logs (Schmoker, 1979), gamma ray logs (Schmoker, 1981), sonic and resistivity logs (Passey et al., 1990), and porosity associated with organic matter; 3) geomechanical evaluation, that includes rock mechanical properties estimation, state of stress determination and brittleness index estimation, using 3 methods: mineral content (Jarvie et al., 2007), elastic properties (Rickman et al., 2008) and a modified method of Grieser-Bray (2007), calibrated with geomechanical field test (XLOT, microfracs and minifracs); and 4) determination of most prospective intervals for completion.

La Luna Formation and La Grita Member of Capacho Formation are mainly composed by carbonatic rocks, with high content of calcite (above 75%) and low content of clay minerals. In both units, the estimation of TOC content varies from 0.50 to 9%. Mechanical properties show moderate values of Poisson's ratio (0.20 to 0.32), high values of Young's modulus (0.80 to 9.60x 106 psi) and UCS (6.20 to 31.00x 106 psi). In the Cretaceous sequence, the state of stress changes according to geographic location in the basin, from normal in northwest region and central lake region, to transcurrent and reverse in southeast region. The brittleness index estimated for different methods varies from 0.54 to 0.85, which indicate that both units may be classify as brittle.

The integration of geomechanical and petrophysical analysis allowed identifying prospective intervals in both units, with thickness between 20 to 100 ft. Therefore, the study indicates that both units show very good conditions for horizontal drilling and hydraulic fracturing. Moreover, the comparison of various estimation methods of TOC content and brittleness index allowed to observe the uncertainty presented by these parameters in analysis of shale plays.
Simulation of Viscosity Enhanced CO2 Nanofluid Alternating Gas in Light Oil Reservoirs
Authors: Gallo G. , Erdmann E.
Published: May 2017

Thickened CO2 nanofluids are a mean to improve volumetric sweep efficiency and gas production in CO2 EOR projects in contrast CO2 flooding. Alternating injection of plain CO2 with thickened CO2 nanofluid is proposed as an economical alternative using the findings of CO2 viscosity enhancement through nanoparticles in current studies. This was achieved by using CMG GEM simulator and contrasting findings with other WAG and CO2 flooding simulations. The simulation was done on a light oil (40 °API) from a Neuquén Basin reservoir. A sensitivity analysis was done to contrast different type of injection schemes.

As CO2 nanofluids can be tailor made in order to adjust their viscosity (and other properties like asphaltene deposition control) diverse results were observed. Nanofluids improve the volumetric sweet efficiency, and even low viscosity increment increase the overall gas utilization and conformance compared to CO2 flooding. Since there is no face change, the use of CO2 based nanofluids can be a mean to control CO2 EOR projects avoiding injectivity loss problems. It was observed that injection of mere nanofluid (without alternating CO2) is not technically nor economically convenient as it decreases production rates and has an overall lower economic performance than both WAG and CO2 flooding. Nevertheless, alternating nanofluid with plain CO2 enables higher sweep efficiency while lowering the operational costs due to lower volumes of nanofluid utilized. Adding nanofluid to a WAG scheme also shows improvements in EOR performance.
Evolution and Evaluation of SRV in Shale Gas Reservoirs: An Application in the Horn River Shale of Canada
Authors: Urban E. , Yousefzadeh A. , Virues C. J. , Aguilera R.
Published: May 2017

A hybrid hydraulic fracture (HHF) model composed of (1) complex discrete fracture networks (DFN) and (2) planar fractures is proposed for modeling the stimulated reservoir volume (SRV). Modeling the SRV is complex and requires a synergetic approach between geophysics, petrophysics, and reservoir engineering. The objective of this paper is to characterize and evaluate the SRV considering the initial hydraulic fracturing efficiency, fracture network complexity, mechanics, and microseismicity distribution along 145 stimulated stages in a multilateral horizontal well on the Muskwa, Otter Park and Evie Formations in the Horn River Shale in Canada.

Hydraulic fracturing jobs in shale reservoirs are designed with a view to achieve economic production by exploiting fracture network complexity. The task involves significant challenges in modeling and forecasting, which complicates the examination of operations to enhance their performance, including refracturing or infill drilling.

In this study, an HHF is run in a numerical simulation model to evaluate the SRV performance in planar and complex fracture networks using microseismicity data collected during 75 stages of hydraulic fracturing in the Horn River shale. Post-fracturing production is appraised with Rate Transient Analysis (RTA) for determining effective permeability under flowing conditions, compare to the numerical simulation and the hydraulic fracturing design.

Fracturing stages with larger fracture patch sizes, associated with the microseismic events in a fixed stress drop, correspond to higher stimulated areas, fracture conductivity, and gas production. Several microseismic events are observed in the heel of the laterals that are aligned to the far field NE stresses, indicated a loss of efficiency along the wellbore lateral during hydraulic fracturing. The hydraulic propagation modeling revealed increment of the leak-off coefficient, related to the natural fractures and communication with other stages. The production performance is evaluated in the numerical model, to measure interference between stages.

The SRV, modeled with HHF networks, is able to match the post-fracturing production history. Fracture mechanics is important in order to understand the flowing performance of the reservoir.

The inclusion of propagating models and RTA allowed to characterize possible fracture geometries in the reservoir and to observe limitations inherent to large dispersion and uncertainty of the microseismicity cloud. Also, to observe areas where the stimulation may have propped natural fractures totally or partially, which will benefit the production of gas.

This study presents a better understanding and characterization of the SRV in shale gas reservoirs, especially in those cases where microseismicity dispersion is problematic and where the SRV is not easily delimited.
A Comprehensive Workflow for Near Real Time Waterflood Management and Production Optimization Using Reduced-Physics and Data-Driven Technologies
Authors: Maqui A. F. , Zhai X. , Suarez Negreira A. , Matringe S. F. , Lozada M. A.
Published: May 2017

Optimizing waterfloods in large fields with complex geology can be an extremely difficult engineering problem. Simulations become overwhelming and tremendously time consuming, while basic classical engineering will not capture enough physics to assess well by well decisions. In this paper we present a novel data-driven, reduced-physics workflow to manage and optimize an exceptionally complex reservoir in Latin America.

The first stage of the workflow involves collecting and validating the field data, including rock and fluid properties, production, injection and pressure data as well as well information, such as trajectories and historical perforations. The reservoir behavior is then modeled following an approach similar to the one by Thiele and Batycky (2006) in the context of streamline simulation. The model represents the reservoir as a network of inter-well connections described by their strength and efficiency. The strength of connection is determined through the solution of a numerical tracer test rather than through streamline-based method like in Thiele and Batycky (2006), which generalizes the method to unstructured or locally refined grids as well as dual permeability systems and allows the method to account for compressibility effects. An empirical fractional flow model is then used to calculate the connection efficiencies. Once the model is complete and calibrated, a cutting-edge optimization algorithm is used to optimize the production-injection strategy based on this network of subsurface connections. Recommendations for adjustments in the production-injection strategies are proposed and model uncertainties are computed through a novel algorithm to compute the associated risks.

The proposed methodology was successfully applied to a giant Latin American waterflooded reservoir with over 800 wells and nearly a hundred years of history. The approach identified an optimized strategy that could deliver a 5% increase in oil production with a 10% reduction in water production. The methodology proposed is fast enough to build and match a new model in a few days; and updating an existing model takes less than an hour as new data comes available.

The proposed method was designed to avoid expensive numerical simulation and to simplify the history-matching process. It can therefore be used daily to help engineers optimize the production-injection strategy of reservoirs. Furthermore, the model can be used for robust short-term forecasting as well as relatively elaborate production mapping.
Optimal Manganese Nutrition Increases Photosynthesis of Immature Pecan Trees
Authors: Sherman Joshua , Heerema Richard J. , VanLeeuwen Dawn , St. Hilaire Rolston
Published: May 2017

Southwestern U.S. pecan [Carya illinoinensis (Wangenh.) K. Koch] orchard soils are typically alkaline and calcareous, making micronutrients such as manganese (Mn) poorly available for root uptake. Manganese is essential to the light reactions of photosynthesis (Pn), but the level of leaf Mn for optimum Pn in pecan is unknown. Our objective was to characterize the relationships of foliar Mn fertilizer applications and leaf Mn nutrition with Pn over a broad range of leaf Mn concentrations. Two experiments were conducted from 2011 to 2012 (Expt. 1) and in 2013 (Expt. 2) in immature, nonbearing ‘Pawnee’ and ‘Western’ pecan orchards near Las Cruces, NM. To create differential leaf tissue Mn concentrations, four Mn spray concentrations were applied foliarly: 0.00, 0.34, 0.68, and 1.3 g Mn/L (Control, Low, Medium, and High, respectively). In Expt. 2, we added a higher Mn concentration (2.7 g Mn/L). Repeated measurements of leaf Pn were made beginning 1 week following a Mn application using a portable Pn system. Across treatments in both studies, final leaf Mn concentrations ranged from 21 to 1488 µg·g−1. Leaves treated with 0.68 g Mn/L had higher Pn than the other treatments in each experiment. In 2013, Pn rates of the leaves treated with 0.68 g Mn/L increased 7.1% and 10.4% over the Control for ‘Pawnee’ and ‘Western’, respectively. Our data confirm an association between leaf tissue Mn and Pn; the leaf tissue Mn concentration at which Pn rates are optimized in immature pecan trees was estimated to be 151.64 (±17.3 se) µg·g−1 Mn.
Delayed Foliar Symptoms Caused by Verticillium dahliae as an Alternative Resistance Trait in Iceberg Lettuce
Authors: Sandoya Germán V. , Subbarao Krishna , Hayes Ryan
Published: May 2017

Verticillium wilt caused by Verticillium dahliae Kleb. is an economically damaging disease of iceberg lettuce on the Central Coast of California. Foliar wilting symptoms that manifest near or at peak market maturity (MM) lead to collapse of the head, making it unmarketable. Complete resistance to race 1 of the pathogen is known, but adequate levels of resistance are not available against race 2. Additional mechanisms or traits that reduce foliar symptoms (FS) are needed to lessen economic losses from this disease. Since the disease affects leaves, the harvested product, identification of iceberg cultivars that delay the onset of FS past peak MM could reduce yield loss from the disease. The goal of this research was to identify iceberg lettuce germplasm with delayed onset of FS. Diverse iceberg cultivars were evaluated in replicated field experiments for MM, FS severity, and adaptation. A few winter-adapted cultivars showed fewer FS past MM and seem to be promising candidates for breeding. These cultivars are not adapted to the California Central Coast where the disease currently predominates. Further studies will determine the usefulness of this trait for breeding improved cultivars for use in V. dahliae–infested fields. Developing new cultivars that combine currently available sources of partial resistance against race 2 with delayed onset of FS could lead to reduced crop losses should race 2 of V. dahliae become widespread.
Distribution of Persea schiedeana in Mexico and Potential for the Production of Fruits with High-quality Oil
Authors: Cruz-Castillo Juan Guillermo , Tinoco-Rueda Juan Ángel , Famiani Franco
Published: May 2017

The fruit of Persea schiedeana is consumed in various rural regions of Mexico and Central America and is mainly sold in local markets. Information regarding the ecological conditions where it grows and the potential for its distribution in Mexico has been little studied. The States of Chiapas, Hidalgo, Oaxaca, Puebla, Tabasco, and Veracruz in Mexico were explored to locate P. schiedeana trees. The ecological conditions of the places where P. schiedeana was found were characterized using thematic cartography and by evaluating the ecological niches to identify potential areas for its distribution. The trees were found in wide physiographic, geological, and edaphic conditions, but they were primarily located in semiwarm humid and warm humid climates. Persea schiedeana trees grow from almost sea level to 2000 m in altitude. Zones with the best developmental conditions for P. schiedeana were in the region of the high mountains in the center of Veracruz and the highland zone of northern Oaxaca. The oil obtained from the fruit of P. schiedeana trees growing at 1300 m had high oleic acid content. This wild fruit has the potential for obtaining new products for cosmetic and alimentary industries.
Rootstock Effects on Fruit Quality among ‘Ray Ruby’ Grapefruit Trees Grown in the Indian River District of Florida
Authors: McCollum Greg , Bowman Kim D.
Published: May 2017

The objective of this experiment was to compare fruit-quality parameters of ‘Ray Ruby’ grapefruit grown on seven rootstocks. Four recent releases from the United States Department of Agriculture (USDA) rootstock breeding program, ‘US-852’, ‘US-897’, ‘US-942’, and ‘US-812’ (all Citrus reticulata × Poncirus trifoliata hybrids), ‘x639’ (C. reticulata × P. trifoliata), along with industry-standard ‘Sour Orange’ and ‘Swingle’ citrumelo were evaluated in a commercial orchard trial in Indian River County, FL. Fruit-quality data were collected in 2011–12 (eight harvests), 2012–13 (five harvests), and 2014 (single harvest). In each season, rootstock effects on fruit size, total solids, and solids acid ratio were significant. ‘Sour orange’ and ‘Swingle’ produced the largest fruit, whereas ‘US-897’ (a semidwarfing rootstock) produced the smallest fruit. Peel thickness (measured only in the 2011–12 season) was greatest in ‘Sour Orange’ early in the season, but not toward the end of the season. Misshapen (“sheep-nosed”) fruit occurred more frequently on ‘Sour Orange’ than on other rootstocks, although the incidence of sheep-nosing was minor. Analysis of variance (ANOVA) for fruit-quality data collected in January of each of the 3 years confirmed that ‘Sour Orange’ and ‘Swingle’ produced the largest fruit and ‘US-897’ produced the smallest fruit. Total solids were the highest in ‘US-897’ and the lowest in ‘x639’ and ‘US-852’. Taken together, our data indicate that ‘US-942’ and ‘US-897’ rootstocks produced fruit with quality characteristics that equaled or exceeded ‘Sour Orange’ and ‘Swingle’, the two most common rootstocks used in the Indian River district.
SSR Markers Reveal the Genetic Diversity of Asian Cercis Taxa at the U.S. National Arboretum
Authors: Thammina Chandra S. , Kidwell-Slak David L. , Lura Stefan , Pooler Margaret R.
Published: May 2017

The redbud (Cercis L. species) is a popular landscape plant grown widely in the United States. There are more than 20 cultivars of eastern redbud (Cercis canadensis L.) and at least three cultivars of Asian taxa (primarily Cercis chinensis Bunge) in the trade. The U.S. National Arboretum (USNA) has a diverse collection of Cercis germplasm collected in North America and Asia. Fourteen genomic simple sequence repeat (genomic-SSR) markers were used to analyze the genetic diversity of 53 accessions of Asian Cercis taxa from our collection, including C. chinensis, Cercis chingii Chun, Cercis gigantea ined., Cercis glabra Pamp., Cercis racemosa Oliv., and Cercis yunnanensis Hu and W. C. Cheng. SSR markers detected an average of 5.7 alleles per locus with a range of two to nine alleles. A dendrogram was generated by unweighted pair group method with arithmetic mean (UPGMA) cluster analysis using the Jaccard similarity coefficient. Four major clusters were identified. Accessions tended to group by taxa or provenance, but with some notable exceptions caused either by misidentification or nomenclatural confusion in the species. This information will be used for collection management and for making decisions in the breeding program to maximize genetic diversity of cultivated Cercis.
Response of Hydroponically Grown Cherry and Fresh Market Tomatoes to Reduced Nutrient Concentration and Foliar Fertilizer Application under Shadenet Conditions
Authors: Maboko Martin M. , Du Plooy Christian P.
Published: May 2017

Reduced nutrient concentration (NC) through fertigation in an open-bag hydroponic system with additional foliar fertilizer application may reduce nutrient wastage and thus decrease the production costs. A study was conducted to determine the effect of foliar fertilizer in combination with reduced NCs on the yield and quality of hydroponically grown cherry and fresh market (FM) tomatoes in a shadenet structure. In the first experiment, FM tomato plants were grown in sawdust fertigated with nutrient solutions containing 100% (control), 75%, 50%, or 25% of the recommended NC. Marketable yield and fruit mineral content were unaffected by NC, whereas the total yield decreased with a decrease in NC. The second and third experiments were on FM and cherry tomatoes, respectively, subjected to four NCs (100%, 75%, 50%, or 25%) and two foliar fertilizer applications (no foliar and foliar application). Fresh and dry weight of FM and cherry tomato plants decreased with a decrease in NC application. Marketable yield on FM tomatoes increased with 50% to 100% NC, whereas the total yield increased with 75% and 100% NC, as compared with 25% NC. Cherry tomatoes produced lower marketable yield at 25% and 50% NC, as compared with 75% and 100% NC. Foliar fertilizer application did not have an effect on FM and cherry tomato yield, but improved the plant dry weight of cherry tomatoes. Fruit and leaf Ca content of FM tomatoes were improved by the decrease in the NC. Fruit mineral content (K, P, Ca, Mg, and Zn) of cherry tomatoes increased with an increase in NC. The improvement in yield was primarily due to nutrient uptake, especially, N, P, and K, as determined in tomato leaves. Reduced NC of 50% can maintain yield and quality of FM tomatoes, whereas application of foliar fertilizer had a limited effect. In cherry tomatoes, yield and fruit mineral content were maintained at 75% NC combined with foliar fertilizer application. The findings of this research may reduce nutrient wastage and result in a cost saving of 25% and 50% on fertilizer input costs on cherry and FM tomatoes, respectively, and reduce the risk associated with water pollution.
Potential of Deficit Irrigation, Irrigation Cutoffs, and Crop Thinning to Maintain Yield and Fruit Quality with Less Water in Northern Highbush Blueberry
Authors: F. Almutairi Khalid , Bryla David R. , Strik Bernadine C.
Published: May 2017

Drought and mandatory water restrictions are limiting the availability of irrigation water in many important blueberry growing regions, such as Oregon, Washington, and California. New strategies are needed to maintain yield and fruit quality with less water. To address the issue, three potential options for reducing water use, including deficit irrigation, irrigation cutoffs, and crop thinning, were evaluated for 2 years in a mature planting of northern highbush blueberry (Vaccinium corymbosum L. ‘Elliott’). Treatments consisted of no thinning and 50% crop removal in combination with either full irrigation at 100% of estimated crop evapotranspiration (ETc), deficit irrigation at 50% ETc (applied for the entire growing season), or full irrigation with irrigation cutoff for 4–6 weeks during early (early- to late-green fruit) or late (fruit coloring to harvest) stages of fruit development. Stem water potential was similar with full and deficit irrigation but, regardless of crop thinning, declined by 0.5–0.6 MPa when irrigation was cutoff early and by >2.0 MPa when irrigation was cutoff late. In one or both years, the fruiting season was advanced with either deficit irrigation or late cutoff, whereas cutting off irrigation early delayed the season. Yield was unaffected by deficit irrigation in plants with a full crop load but was reduced by an average of 35% when irrigation was cutoff late each year. Cutting off irrigation early likewise reduced yield, but only in the 2nd year when the plants were not thinned; however, early cutoff also reduced fruit soluble solids and berry weight by 7% to 24% compared with full irrigation. Cutting off irrigation late produced the smallest and firmest fruit with the highest soluble solids and total acidity among the treatments, as well as the slowest rate of fruit loss in cold storage. Deficit irrigation had the least effect on fruit quality and, based on these results, appears to be the most viable option for maintaining yield with less water in northern highbush blueberry. Relative to full irrigation, the practice reduced water use by 2.5 ML·ha−1 per season.
Do Real and Fictitious Plant Brands Differ in Brand Recognition, Awareness, Purchase Intention, and Visual Activity?
Authors: Behe Bridget K. , Huddleston Patricia T. , Hall Charles R. , Khachatryan Hayk , Campbell Benjamin
Published: May 2017

Brands differentiate products from each other and help create the perception of added value. They influence product choice at the point of purchase with >70% of all buying decisions made in the store. Brands are often one of a few pieces of information consumers use to make product choices. Prior research showed that consumers had a greater likelihood to buy plant brands they had previously seen. To advance both the academic and practitioners’ understanding of plant brands, we sought to investigate the role of real and fictitious brands and their effects on visual activity and purchase intentions. Would simply including information on the container (e.g., fictitious brand) sway visual activity and purchase intentions? To investigate this notion, we conducted an in-person survey with a conjoint design in four states during May and June, 2015, using two flowering annuals and two flowering shrubs. Our goals were to assess consumers’ expressed and implicit preferences and, at the same time, monitor their gaze to determine how subjects used the real and fictitious brands as cues in their purchase decision. We showed 214 study participants digital images of 16 plants, varying the plant type, brand, and price; asked about brand awareness and familiarity; collected demographic and plant purchase information; and recorded their gaze as they viewed the images. We segmented the sample into three clusters, comparing their brand awareness and familiarity, conjoint analysis results, and the two visual measures: time to first fixation (TFF) and total fixation duration (TFD) on the container. The three clusters identified varied in their level of brand recognition and awareness but were similar in the relative importance and part-worth utility (PWU) mean scores, indicating a relatively similar decision process. The visual activity varied slightly by brand, but the fictitious brand captured and held visual attention similarly to the two established national brands.
Dwarfing Effect of Apple Rootstocks Is Intimately Associated with Low Number of Fine Roots
Authors: An Haishan , Luo Feixiong , Wu Ting , Wang Yi , Xu Xuefeng , Zhang Xinzhong , Han Zhenhai
Published: May 2017

Fine root (≤2 mm in diameter) systems play a pivotal role in water and mineral uptake in higher plants. However, the impact of fine root architecture on tree growth and development is not fully understood, especially in apple trees. Here, we summarize a 6-year-trial study using minirhizotrons to investigate the relationships between fine root production, mortality, and longevity in ‘Red Fuji’ trees grafted on five different rootstocks/interstems. Based on root length density (RLD), fine root production and mortality were markedly lower in ‘Red Fuji’ trees growing on dwarfing M.9 (M.9) and Shao series no. 40 (SH.40) rootstocks than in trees on standard Malus robusta ‘Baleng Crab’ (BC) rootstock. The use of M.9 and SH.40 as interstems led to an extensive reduction in fine root production and mortality in comparison with BC rootstock. Root number density (RND), but not average root length (ARL), showed similar patterns to RLD. About one-half of fine roots in ‘Red Fuji’ tree growing on M.9 were scattered within the top 0–20 cm of topsoil, indicating shallow root system in M.9, whereas in trees on BC, 55.15% of fine roots were distributed between 100- and 150-cm soil depth, indicating a deep root architecture. The addition of interstems did not alter fine root soil-depth distribution. For all rootstocks/interstems, fine roots with a life span of less than 80 days were generated in spring and summer, but fine roots which lived for more than 81 days were produced almost all the year round. In conclusion, lower fine root numbers were associated with the dwarfing effect in dwarfing rootstocks/interstems, but ARL and shallower rooting were not.
Growth and Bioactive Compound Synthesis in Cultivated Lettuce Subject to Light-quality Changes
Authors: Son Ki-Ho , Lee Jin-Hui , Oh Youngjae , Kim Daeil , Oh Myung-Min , In Byung-Chun
Published: May 2017

This study aimed to determine the effect of changes in light quality on the improvement of growth and bioactive compound synthesis in red-leaf lettuce (Lactuca sativa L. ‘Sunmang’) grown in a plant factory with electrical lighting. Lettuce seedlings were subjected to 12 light treatments combining five lighting sources: red (R; 655 nm), blue (B; 456 nm), and different ratios of red and blue light combined with three light-emitting diodes [LEDs (R9B1, R8B2, and R6B4)]. Treatments were divided into control (continuous irradiation of each light source for 4 weeks), monochromatic (changing from R to B at 1, 2, or 3 weeks after the onset of the experiments), and combined (changing from R9B1 to R8B2 or R6B4 at 2 or 3 weeks after the onset of the experiments). Growth and photosynthetic rates of lettuce increased with increasing ratios of red light, whereas chlorophyll and antioxidant phenolic content decreased with increasing ratios of red light. Individual phenolic compounds, including chlorogenic, caffeic, chicoric, and ferulic acids, and kaempferol, showed a similar trend to that of total phenolics. Moreover, transcript levels of phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS) genes were rapidly upregulated by changing light quality from red to blue. Although the concentration of bioactive compounds in lettuce leaves enhanced with blue light, their contents per lettuce plant were more directly affected by red light, suggesting that biomass as well as bioactive compounds’ accumulation should be considered to enhance phytochemical production. In addition, results suggested that growth and antioxidant phenolic compound synthesis were more sensitive to monochromatic light than to combined light variations. In conclusion, the adjustment of light quality at a specific growth stage should be considered as a strategic tool for improving crop yield, nutritional quality, or both in a plant factory with electrical lighting.