scholarly journals Chrysopogon zizanioides (vetiver).

2020 ◽  
Author(s):  
Julissa Rojas-Sandoval
Keyword(s):  
Root System ◽  
Water Conservation ◽  
Native Species ◽  
Soil Structure ◽  
The Philippines ◽  
Climatic Conditions ◽  
Wild Type ◽  
Dissolved Nutrients ◽  
Chrysopogon Zizanioides ◽  
Wide Range

Abstract Chrysopogon zizanioides is a grass native to Asia, now widely introduced and cultivated in tropical and subtropical regions of the world. There are two types, an infertile domesticated type and a fertile wild type. C. zizanioides can grow in a wide range of soils and climatic conditions and is very tolerant of disturbance including grazing, fire, floods and drought. This is in part due to its dense root system that can reach depths of over 3 m. All these features have made this species an excellent option for soil and water conservation (among other uses), but also make the fertile wild type of this plant a problematic invasive species. Once established, it grows very densely and has the potential to displace other plant species including other grasses. Currently, vetiver is listed as invasive in China, Fiji, Costa Rica, Anguilla and the Philippines. This species is highly efficient in absorbing dissolved nutrients such as nitrogen and phosphorous, and its dense root system can directly alter the soil structure and modify or inhibit nutrient and water acquisition by native species. Due to its deep root system, it is difficult to remove manually. It can be controlled by dense shade and by digging up the crown, and it is susceptible to glyphosate.

The effect of cover crops on soil structure is mainly driven by root architecture

2021 ◽  
Author(s):  
Maik Lucas ◽  
Linh Nguyen ◽  
Andrey Guber ◽  
Alexandra Kravchenko
Keyword(s):  
Root System ◽  
Cover Crops ◽  
Soil Structure ◽  
Image Features ◽  
Small Scale ◽  
Pore Characteristics ◽  
Pore Connectivity ◽  
Imaging Protocol ◽  
X Ray ◽  
Wide Range

<p>Cover crops are known to increase macroporosity and pore connectivity, thus having a beneficial effect on soil hydraulic properties such as saturated hydraulic conductivity, However, cover crop species typically used encompass a variety of contrasting root architectures and their effects on small-scale pore properties are difficult to quantify.</p><p>Here we explore the influence of five different cover crops (annual ryegrass, Austrian winter pea, dwarf essex rapeseed, oats, and oilseed radish) on soil structure with X-ray µCT. Undisturbed samples were taken from an experiment with these cover crops on Kellogg Biological Station (Michigan, USA) in October 2019. Two soil columns with a diameter of 5 cm were taken in 5 - 10 cm depth from each of three replicated plots per plant species and scanned with X-ray µCT at a resolution of 18 µm.</p><p>These images will be used to characterize pore structure in terms of pore size distribution, pore connectivity. In addition, a new imaging protocol will be used, which combines existing ones with a random forest classifier to segment image features such as pores, biopores and roots simultaneously.</p><p>First, the results reveal that different cover crops indeed result in different pore characteristics.  The fibrous root system of oats leads to the highest volume of narrow macropores and increased their connectivity, while the tap root system of dwarf essex rapeseed mainly effected wide macropores.  The highly diverse root system of Australian winter pea increased a wide range of pore sizes and thus resulted in the highest visible porosity.</p><p>The current study is funded by a grant from USDA Organic Transition program</p>

scholarly journals Contrasting Patterns of Pomacea maculata Establishment and Dispersal in an Everglades Wetland Unit and a Central Florida Lake

Diversity ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 183
Author(s):  
Gutierre ◽  
Darby ◽  
Valentine-Darby ◽  
Mellow ◽  
Therrien ◽  
...  
Keyword(s):  
Water Conservation ◽  
Native Species ◽  
Littoral Zone ◽  
Habitat Degradation ◽  
Snail Species ◽  
Stem Density ◽  
Apple Snail ◽  
Conservation Area ◽  
Wide Range ◽  
Pomacea Maculata

The spread of non-native species raises concerns about native species displacement, while other negative effects on native species (e.g., habitat degradation) should also be considered. The highly invasive non-native apple snail Pomacea maculata has raised such concerns as it has become established in a wide range of aquatic systems worldwide. While monitoring native Florida P. paludosa populations in Lake Tohopekaliga (LTOHO) from 2001 to 2009 and in Water Conservation Area 3A (WCA3A, Everglades) from 2006 to 2015, we opportunistically documented the establishment and distribution of P. maculata. We estimated snail densities and recorded egg cluster presence in three study sites (12 total plots, LTOHO) and 137 sites (WCA3). On LTOHO, native snails were absent or at very low densities prior to finding P. maculata. Few snails of either species were found in high-stem-density vegetation of the littoral zone. Pomacea maculata immigration into the littoral zone occurred following managed vegetation removal, and Hydrilla verticillata proliferation in LTOHO likely contributed to the spread of P. maculata. We found both native and non-native apple snail species in many WCA3A sites following P. maculata invasion. We initially found the non-native snail in two sites in southern WCA3A; they were mostly restricted to within three kilometers of initial sites over the next four years. Overall plant community compositions in LTOHO and WCA3A appeared less impacted than expected based on previous reports of P. maculata invasions.

scholarly journals Silicon Effects on the Root System of Diverse Crop Species Using Root Phenotyping Technology

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 885
Author(s):  
Pooja Tripathi ◽  
Sangita Subedi ◽  
Abdul Latif Khan ◽  
Yong-Suk Chung ◽  
Yoonha Kim
Keyword(s):  
Root System ◽  
Root Morphology ◽  
Morphological Traits ◽  
Crop Production ◽  
Spatial Configuration ◽  
Global Climate ◽  
Learning Technologies ◽  
Climate Change Scenarios ◽  
Crop Species ◽  
Wide Range

Roots play an essential function in the plant life cycle, as they utilize water and essential nutrients to promote growth and plant productivity. In particular, root morphology characteristics (such as length, diameter, hairs, and lateral growth) and the architecture of the root system (spatial configuration in soil, shape, and structure) are the key elements that ensure growth and a fine-tuned response to stressful conditions. Silicon (Si) is a ubiquitous element in soil, and it can affect a wide range of physiological processes occurring in the rhizosphere of various crop species. Studies have shown that Si significantly and positively enhances root morphological traits, including root length in rice, soybean, barley, sorghum, mustard, alfalfa, ginseng, and wheat. The analysis of these morphological traits using conventional methods is particularly challenging. Currently, image analysis methods based on advanced machine learning technologies allowed researchers to screen numerous samples at the same time considering multiple features, and to investigate root functions after the application of Si. These methods include root scanning, endoscopy, two-dimensional, and three-dimensional imaging, which can measure Si uptake, translocation and root morphological traits. Small variations in root morphology and architecture can reveal different positive impacts of Si on the root system of crops, with or without exposure to stressful environmental conditions. This review comprehensively illustrates the influences of Si on root morphology and root architecture in various crop species. Furthermore, it includes recommendations in regard to advanced methods and strategies to be employed to maintain sustainable plant growth rates and crop production in the currently predicted global climate change scenarios.

scholarly journals Environmental Drivers and Age Trends in Site Productivity for Oak in Southern Poland

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 209
Author(s):  
Luiza Tymińska-Czabańska ◽  
Jarosław Socha ◽  
Marek Maj ◽  
Dominika Cywicka ◽  
Xo Viet Hoang Duong
Keyword(s):  
Nitrogen Deposition ◽  
Management Practices ◽  
Additive Model ◽  
Climatic Conditions ◽  
Environmental Indicators ◽  
Environmental Drivers ◽  
Site Productivity ◽  
Site Factors ◽  
Wide Range ◽  
Si Model

Site productivity provides critical information for forest management practices and is a fundamental measure in forestry. It is determined using site index (SI) models, which are developed using two primary groups of methods, namely, phytocentric (plant-based) or geocentric (earth-based). Geocentric methods allow for direct site growth modelling, in which the SI is predicted using multiple environmental indicators. However, changes in non-static site factors—particularly nitrogen deposition and rising CO2 concentration—lead to an increase in site productivity, which may be visible as an age trend in the SI. In this study, we developed a geocentric SI model for oak. For the development of the SI model, we used data from 150 sample plots, representing a wide range of local topographic and site conditions. A generalized additive model was used to model site productivity. We found that the oak SI depended predominantly on physicochemical soil properties—mainly nitrogen, carbon, sand, and clay content. Additionally, the oak SI value was found to be slightly shaped by the topography, especially by altitude above sea level, and topographic position. We also detected a significant relationship between the SI and the age of oak stands, indicating the long-term increasing site productivity for oak, most likely caused by nitrogen deposition and changes in climatic conditions. The developed geocentric site productivity model for oak explained 77.2% of the SI variation.

scholarly journals Soil Nitrogen Dynamics in a Managed Temperate Grassland Under Changed Climatic Conditions

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 931
Author(s):  
Mona Giraud ◽  
Jannis Groh ◽  
Horst H. Gerke ◽  
Nicolas Brüggemann ◽  
Harry Vereecken ◽  
...  
Keyword(s):  
Nitrogen Uptake ◽  
Inorganic Nitrogen ◽  
Nitrogen Concentration ◽  
Nitrogen Dynamics ◽  
Climatic Conditions ◽  
Undisturbed Soil ◽  
Nitrogen Emissions ◽  
Growing Period ◽  
Grassland Type ◽  
Wide Range

Grasslands are one of the most common biomes in the world with a wide range of ecosystem services. Nevertheless, quantitative data on the change in nitrogen dynamics in extensively managed temperate grasslands caused by a shift from energy- to water-limited climatic conditions have not yet been reported. In this study, we experimentally studied this shift by translocating undisturbed soil monoliths from an energy-limited site (Rollesbroich) to a water-limited site (Selhausen). The soil monoliths were contained in weighable lysimeters and monitored for their water and nitrogen balance in the period between 2012 and 2018. At the water-limited site (Selhausen), annual plant nitrogen uptake decreased due to water stress compared to the energy-limited site (Rollesbroich), while nitrogen uptake was higher at the beginning of the growing period. Possibly because of this lower plant uptake, the lysimeters at the water-limited site showed an increased inorganic nitrogen concentration in the soil solution, indicating a higher net mineralization rate. The N2O gas emissions and nitrogen leaching remained low at both sites. Our findings suggest that in the short term, fertilizer should consequently be applied early in the growing period to increase nitrogen uptake and decrease nitrogen losses. Moreover, a shift from energy-limited to water-limited conditions will have a limited effect on gaseous nitrogen emissions and nitrate concentrations in the groundwater in the grassland type of this study because higher nitrogen concentrations are (over-) compensated by lower leaching rates.

A Philippine ‘coolie trade’: Trade and exploitation of Chinese labour in Spanish colonial Philippines, 1850–98

2020 ◽  
Vol 51 (3) ◽  
pp. 457-483
Author(s):  
Mònica Ginés-Blasi
Keyword(s):  
Nineteenth Century ◽  
The Philippines ◽  
Spanish Colonial ◽  
Commercial Activities ◽  
Wide Range ◽  
Coolie Trade

Chinese immigration to the Philippines has traditionally been studied in relation to commercial activities. But between 1850 and 1898, there was an unparalleled influx of Chinese labourers, which raised the number of Chinese residents to 100,000. This influx was fuelled by the abundant profits obtained by Chinese brokers and foremen, Spanish institutions and authorities in Manila, consuls in China, and Spanish and British ship captains, all of whom extracted excessive fees and taxes from the labourers. The trade in and the exploitation of Chinese labourers in the Philippines have yet to be thoroughly researched. This article shows that the import and abuse of Chinese labourers in and to the Philippines continued throughout the second half of the nineteenth century, and that, despite some anti-Chinese Spanish colonial rhetoric, a wide range of actors and institutions, both in China and in the Philippines, took advantage of this unprecedented inflow of immigrants.

scholarly journals Energy implications of the millennium drought on urban water cycles in Southeast Australian cities

2017 ◽  
Vol 18 (1) ◽  
pp. 214-221
Author(s):  
K. L. Lam ◽  
P. A. Lant ◽  
S. J. Kenway
Keyword(s):  
Water Supply ◽  
Water Conservation ◽  
Energy Use ◽  
Water Supply Systems ◽  
Urban Water ◽  
Demand Side ◽  
Related Energy ◽  
Millennium Drought ◽  
Wide Range ◽  
Supply Systems

Abstract During the Millennium Drought in Australia, a wide range of supply-side and demand-side water management strategies were adopted in major southeast Australian cities. This study undertakes a time-series quantification (2001–2014) and comparative analysis of the energy use of the urban water supply systems and sewage systems in Melbourne and Sydney before, during and after the drought, and evaluates the energy implications of the drought and the implemented strategies. In addition, the energy implications of residential water use in Melbourne are estimated. The research highlights that large-scale adoption of water conservation strategies can have different impacts on energy use in different parts of the urban water cycle. In Melbourne, the per capita water-related energy use reduction in households related to showering and clothes-washing alone (46% reduction, 580 kWhth/p/yr) was far more substantial than that in the water supply system (32% reduction, 18 kWhth/p/yr). This historical case also demonstrates the importance of balancing supply- and demand-side strategies in managing long-term water security and related energy use. The significant energy saving in water supply systems and households from water conservation can offset the additional energy use from operating energy-intensive supply options such as inter-basin water transfers and seawater desalination during dry years.

The Philippines in 2006: Democracy and Its Discontents

Asian Survey ◽  
2007 ◽  
Vol 47 (1) ◽  
pp. 175-182 ◽  
Author(s):  
Sheila S. Coronel
Keyword(s):  
High Growth ◽  
Armed Forces ◽  
The Philippines ◽  
Political Uncertainty ◽  
Foreign Investments ◽  
State Of Emergency ◽  
Wide Range

A wide range of groups attempted to force President Gloria Macapagal-Arroyo out of power in 2006 but failed. The attempt prompted the declaration of a state of emergency and plunged the country deeper into crisis. The year was marked by internecine rivalries among the country's elites, restiveness in the armed forces, and a renewed campaign against communists. But the economy seemed insulated from political uncertainty, posting high growth because of rising export receipts, more foreign investments, and record remittances from overseas workers.

Fire regime shift linked to increased forest density in a piñon–juniper savanna landscape

2014 ◽  
Vol 23 (2) ◽  
pp. 234 ◽  
Author(s):  
Ellis Q. Margolis
Keyword(s):  
Regime Shift ◽  
Fire History ◽  
Fire Regime ◽  
Fire Regimes ◽  
Fire Frequency ◽  
Climatic Conditions ◽  
Tree Density ◽  
High Severity ◽  
Wide Range ◽  
In Fire

Piñon–juniper (PJ) fire regimes are generally characterised as infrequent high-severity. However, PJ ecosystems vary across a large geographic and bio-climatic range and little is known about one of the principal PJ functional types, PJ savannas. It is logical that (1) grass in PJ savannas could support frequent, low-severity fire and (2) exclusion of frequent fire could explain increased tree density in PJ savannas. To assess these hypotheses I used dendroecological methods to reconstruct fire history and forest structure in a PJ-dominated savanna. Evidence of high-severity fire was not observed. From 112 fire-scarred trees I reconstructed 87 fire years (1547–1899). Mean fire interval was 7.8 years for fires recorded at ≥2 sites. Tree establishment was negatively correlated with fire frequency (r=–0.74) and peak PJ establishment was synchronous with dry (unfavourable) conditions and a regime shift (decline) in fire frequency in the late 1800s. The collapse of the grass-fuelled, frequent, surface fire regime in this PJ savanna was likely the primary driver of current high tree density (mean=881treesha–1) that is >600% of the historical estimate. Variability in bio-climatic conditions likely drive variability in fire regimes across the wide range of PJ ecosystems.

scholarly journals Genotype-Specific Signal Generation Based on Digestion of 3-Way DNA Junctions: Application to KRAS Variation Detection

2006 ◽  
Vol 52 (10) ◽  
pp. 1855-1863 ◽  
Author(s):  
Giulia Amicarelli ◽  
Daniel Adlerstein ◽  
Erlet Shehi ◽  
Fengfei Wang ◽  
G Mike Makrigiorgos
Keyword(s):  
Nucleic Acid ◽  
Concordance Rate ◽  
Signal Generation ◽  
Sequence Variants ◽  
Wild Type ◽  
Specific Signal ◽  
Novel Technology ◽  
Dna Junctions ◽  
Wide Range ◽  
Kras Codon

Abstract Background: Genotyping methods that reveal single-nucleotide differences are useful for a wide range of applications. We used digestion of 3-way DNA junctions in a novel technology, OneCutEventAmplificatioN (OCEAN) that allows sequence-specific signal generation and amplification. We combined OCEAN with peptide-nucleic-acid (PNA)-based variant enrichment to detect and simultaneously genotype v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) codon 12 sequence variants in human tissue specimens. Materials and Methods: We analyzed KRAS codon 12 sequence variants in 106 lung cancer surgical specimens. We conducted a PNA-PCR reaction that suppresses wild-type KRAS amplification and genotyped the product with a set of OCEAN reactions carried out in fluorescence microplate format. The isothermal OCEAN assay enabled a 3-way DNA junction to form between the specific target nucleic acid, a fluorescently labeled “amplifier”, and an “anchor”. The amplifier-anchor contact contains the recognition site for a restriction enzyme. Digestion produces a cleaved amplifier and generation of a fluorescent signal. The cleaved amplifier dissociates from the 3-way DNA junction, allowing a new amplifier to bind and propagate the reaction. Results: The system detected and genotyped KRAS sequence variants down to ∼0.3% variant-to-wild-type alleles. PNA-PCR/OCEAN had a concordance rate with PNA-PCR/sequencing of 93% to 98%, depending on the exact implementation. Concordance rate with restriction endonuclease-mediated selective-PCR/sequencing was 89%. Conclusion: OCEAN is a practical and low-cost novel technology for sequence-specific signal generation. Reliable analysis of KRAS sequence alterations in human specimens circumvents the requirement for sequencing. Application is expected in genotyping KRAS codon 12 sequence variants in surgical specimens or in bodily fluids, as well as single-base variations and sequence alterations in other genes.

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