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2024

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Articles 4681 - 4710 of 8055

Full-Text Articles in Physical Sciences and Mathematics

Constraints On Metastable Superheavy Dark Matter Coupled To Sterile Neutrinos With The Pierre Auger Observatory, A. Abdul Halim, P. Abreu, M. Aglietta, I. Allekotte, K. Almeida Cheminant, A. Almela, B. Fick, K. Nguyen, D. Nitz, Et Al. Apr 2024

Constraints On Metastable Superheavy Dark Matter Coupled To Sterile Neutrinos With The Pierre Auger Observatory, A. Abdul Halim, P. Abreu, M. Aglietta, I. Allekotte, K. Almeida Cheminant, A. Almela, B. Fick, K. Nguyen, D. Nitz, Et Al.

Michigan Tech Publications, Part 2

Dark matter particles could be superheavy, provided their lifetime is much longer than the age of the Universe. Using the sensitivity of the Pierre Auger Observatory to ultrahigh energy neutrinos and photons, we constrain a specific extension of the Standard Model of particle physics that meets the lifetime requirement for a superheavy particle by coupling it to a sector of ultralight sterile neutrinos. Our results show that, for a typical dark coupling constant of 0.1, the mixing angle θm between active and sterile neutrinos must satisfy, roughly, θm≲1.5×10-6(MX/109 GeV)-2 for a mass MX of the dark-matter particle between 108 GeV …

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Arsenic Contamination Needs Serious Attention: An Opinion And Global Scenario, Abhijnan Bhat School Of Food Science And Environmental Health, Kamna Ravi Health, Engineering & Materials Sciences (Hems) Hub, Furong Tian Nanolab Research Centre, Baljit Singh Micra Biodiagnostics Technology Gateway Apr 2024

Arsenic Contamination Needs Serious Attention: An Opinion And Global Scenario, Abhijnan Bhat School Of Food Science And Environmental Health, Kamna Ravi Health, Engineering & Materials Sciences (Hems) Hub, Furong Tian Nanolab Research Centre, Baljit Singh Micra Biodiagnostics Technology Gateway

Articles

Arsenic (As) contamination is a serious global concern, polluting our natural resources, including water and soil, and posing a danger to the environment and public health. Arsenic is present in the groundwater of several countries and this contaminated water is used for irrigation, drinking, and food preparation, which poses the greatest threat to public health. Nearly 106 countries are affected by groundwater arsenic contamination and an estimated 230 million individuals worldwide are exposed to its adverse health effects, including increased cancer risks, associated cardiovascular disease and diabetes, skin lesions, neurological effects, kidney damage, and foetal or cognitive development-related complications. Arsenic …

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Comparing Cognitive Theories Of Learning Transfer To Advance Cybersecurity Instruction, Assessment, And Testing, Daniel T. Hickey Ph.D., Ronald J. Kantor Apr 2024

Comparing Cognitive Theories Of Learning Transfer To Advance Cybersecurity Instruction, Assessment, And Testing, Daniel T. Hickey Ph.D., Ronald J. Kantor

Journal of Cybersecurity Education, Research and Practice

The cybersecurity threat landscape evolves quickly, continually, and consequentially. This means that the transfer of cybersecurity learning is crucial. We compared how different recognized “cognitive” transfer theories might help explain and synergize three aspects of cybersecurity education. These include teaching and training in diverse settings, assessing learning formatively & summatively, and testing & measuring achievement, proficiency, & readiness. We excluded newer sociocultural theories and their implications for inclusion as we explore those theories elsewhere. We first summarized the history of cybersecurity education and proficiency standards considering transfer theories. We then explored each theory and reviewed the most relevant cybersecurity education …

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A Search For Intermediate-Mass Black Holes In Compact Stellar Systems Through Optical Emissions From Tidal Disruption Events, Richard T. Pomeroy, Mark A. Norris Apr 2024

A Search For Intermediate-Mass Black Holes In Compact Stellar Systems Through Optical Emissions From Tidal Disruption Events, Richard T. Pomeroy, Mark A. Norris

Physics and Astronomy Faculty Publications and Presentations

Intermediate-mass black holes (IMBH) are expected to exist in globular clusters (GCs) and compact stellar systems (CSS) in general, but none have been conclusively detected. Tidal disruption events (TDEs), where a star is tidally disrupted by the gravitational field of a black hole, have been observed to occur around the supermassive black holes (SMBH) found at the centres of galaxies, and should also arise around IMBHs, especially in the dense stellar cores of CSS's. However, to date none have been observed in such environments. Using data from the Zwicky Transient Facility (ZTF) we search for TDEs associated with CSS, but …

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Dispersion Of Artificial Tracers In Ventilated Caves, Claudio Pastore, Eric Weber, Frédéric Doumenc, Pierre-Yves Jeannin, Marc Lütscher Apr 2024

Dispersion Of Artificial Tracers In Ventilated Caves, Claudio Pastore, Eric Weber, Frédéric Doumenc, Pierre-Yves Jeannin, Marc Lütscher

International Journal of Speleology

Artificial CO2 was used as a tracer along ventilated karst conduits to infer airflow and investigate tracer dispersion. In the karst vadose zone, cave ventilation is an efficient mode of transport for heat, gases and aerosols and thus drives the spatial distribution of airborne particles. Modelling this airborne transport requires geometrical and physical parameters of the conduit system, including the cross-sectional areas, the airflow and average air speed, as well as the longitudinal dispersion coefficient which describes the spreading of a solute. Four gauging tests were carried out in one mine (artificial conduit) and two ventilated caves (natural conduits). …

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A Note On Umbilic Points At Infinity, Brendan Guilfoyle Apr 2024

A Note On Umbilic Points At Infinity, Brendan Guilfoyle

Publications

In this note a definition of umbilic point at infinity is proposed, at least for surfaces that are homogeneous polynomial graphs over a plane in Euclidean 3-space. This is a stronger definition than that of Toponogov in his study of complete convex surfaces, and allows one to distinguish between different umbilic points at infinity. It is proven that all such umbilic points at infinity are isolated, that they occur in pairs and are the zeroes of the projective extension of the third fundamental form, as developed in Guilfoyle and Ortiz-Rodríguez (Math Proc R Ir Acad 123A(2), 63–94, 2023). A geometric …

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Search For Extreme Mass Ratio Inspirals Using Particle Swarm Optimization And Reduced Dimensionality Likelihoods, Xiao-Bo Zou, Soumya Mohanty, Hong-Gang Luo, Yu-Xiao Liu Apr 2024

Search For Extreme Mass Ratio Inspirals Using Particle Swarm Optimization And Reduced Dimensionality Likelihoods, Xiao-Bo Zou, Soumya Mohanty, Hong-Gang Luo, Yu-Xiao Liu

Physics and Astronomy Faculty Publications and Presentations

Extreme-mass-ratio inspirals (EMRIs) are significant observational targets for spaceborne gravitational wave detectors, namely, LISA, Taiji, and Tianqin, which involve the inspiral of stellar-mass compact objects into massive black holes (MBHs) with a mass range of approximately 104 ∼107𝑀⊙ . EMRIs are estimated to produce long-lived gravitational wave signals with more than 105 cycles before plunge, making them an ideal laboratory for exploring the strong-gravity properties of the spacetimes around the MBHs, stellar dynamics in galactic nuclei, and properties of the MBHs itself. However, the complexity of the waveform model, which involves the superposition of multiple harmonics, as well as the …

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Extraction Of Sandalwood Essential Oil: Isolating Α/Β-Santalol, Maeren Horton Apr 2024

Extraction Of Sandalwood Essential Oil: Isolating Α/Β-Santalol, Maeren Horton

Dr. Jay W. Boland Undergraduate Research Symposium

Sandalwood oil is a high-value essential oil extracted from the heartwood of East Indian Sandalwood (Santalum album) and Australian Sandalwood (Santalum Spicatum) and is prominent in numerous luxury perfume brands due to its exotic, versatile, and pleasant fragrance. α-Santalol, the main aromatic constituent in S. album and S. spicatum, exhibits anti-aging, antioxidant, anti-inflammatory, and potential anti-cancer properties, accounting for the oil’s medicinal and dermatologic applications. High demand of the oil resulted in excessive harvesting of sandalwood trees, necessitating a need to develop more efficient and sustainable extraction methods. This study investigates the efficiency of traditional extraction methods of sandalwood oil …

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Analysis Of The Key Performance Indicators Between Lithologies On Mine To Crusher, Janine Figueiredo, Vidal Torres, Rodolfo Cruz, Douglas Moreira Apr 2024

Analysis Of The Key Performance Indicators Between Lithologies On Mine To Crusher, Janine Figueiredo, Vidal Torres, Rodolfo Cruz, Douglas Moreira

Journal of Sustainable Mining

The evolution of the mineral economy requires greater technological developments to find a better use of resources and reserves through the relationships between the characteristics of the rocks and the need to enable the entire mining enterprise. This study focuses on the development of new rock blasting technologies that result in a more optimized fragmentation according to the lithology in the feed of the primary crusher. This methodology is known as Mine to Crusher, through which it becomes possible to minimize costs in the future prospecting of the mine and maximize productivity. For this methodology to be developed, it was …

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Effect Of Lowered Light Quality (R:Fr Ratio) At Targeted Organs On Branching Of Trifolium Repens, M J.M Hay, Ch Robin, P C.D Newton, A Cresswell, J Tilbrook Apr 2024

Effect Of Lowered Light Quality (R:Fr Ratio) At Targeted Organs On Branching Of Trifolium Repens, M J.M Hay, Ch Robin, P C.D Newton, A Cresswell, J Tilbrook

IGC Proceedings (1993-2023)

This report examined results from four similarly conducted experiments using Trifolium repens in which the R:FR ratio but not the photosynthetically active radiation (PAR) of incident light was altered at specific organ(s) of several successive phytomers or just at a single phytomer. Results indicate the local response to lowered R:FR light treatment was similar irrespective of the number of phytomers treated. This response pattern provides the means whereby plants can initiate strong localised responses to a heterogeneous light environment.

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Theoretical And Observed Relationships Between Defoliation And Partitioning In Grasses, C P.D. Birch, B Thornton Apr 2024

Theoretical And Observed Relationships Between Defoliation And Partitioning In Grasses, C P.D. Birch, B Thornton

IGC Proceedings (1993-2023)

A model is presented that analyses the potential effect of vertebrate grazing on the partitioning of grasses. Its conclusions are: 1) When grazing is sufficiently frequent and severe, grasses can increase their net increase in biomass by partitioning growth to reserves. 2) Partitioning growth to reserves greatly reduces leaf growth between defoliations. After repeated clipping, dryland browntop (Agrostis castellana) and red fescue (Festuca rubra) allocated a smaller proportion of growth between defoliations to leaves than ryegrass (Lolium perenne) or rough meadow-grass (Poa trivialis). Browntop and fescue achieved less leaf growth than ryegrass …

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Effects Of Light Intensity And Defoliation On The Receptiveness For Primary Induction In Festuca Pratensis Huds, Lars T. Havstad Apr 2024

Effects Of Light Intensity And Defoliation On The Receptiveness For Primary Induction In Festuca Pratensis Huds, Lars T. Havstad

IGC Proceedings (1993-2023)

Seedlings of Festuca pratensis Huds. (cv. Salten) were raised at three different light intensities (141, 85 or 28 (mol m-2s-1 ) for 7 weeks after emergence and then either left uncut or defoliated 40 or 80% of total leaf area, before transfer to primary induction (6°C, natural short days) for 12, 15 or 18 weeks. Percentage of heading plants was more affected by the duration of primary induction than by light intensity and defoliation prior to induction. The results lend no support to the existence of a juvenile stage in seedlings of Festuca pratensis. Defoliation had less influence on …

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Water Use Efficiency In Chilean And Argentine Humid Temperate Grass-Legume Pastures, H G. Landi, M H. Wade, V Garcia De Cortazar, D E. Dalla Valle Apr 2024

Water Use Efficiency In Chilean And Argentine Humid Temperate Grass-Legume Pastures, H G. Landi, M H. Wade, V Garcia De Cortazar, D E. Dalla Valle

IGC Proceedings (1993-2023)

At two sites in Argentina and Chile five levels of water input were applied to four sown pastures of varying ages during spring and summer. The pastures consisted principally of C3 grasses and legumes, some of which were sown such as Lolium perenne, Trifolium repens, Dactylis glomerata. Dry matter (DM) production was measured and related to the estimated total evapotranspiration (ET): responses were both highly linear. Both responses to ET and absolute yields were higher at the Argentinian than at the Chilean site: respectively 10.7 and 15.2 kg DM/mm water evapotranspired. Nevertheless the calculated indices of sensitivity (Ky) of Doorenbos …

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Effects Of Accelerate Ageing And Low Temperatures On Germination Of Range Grasses, C Cabeza, R E. Brevedan, M G. Klich, M A. Varillas Apr 2024

Effects Of Accelerate Ageing And Low Temperatures On Germination Of Range Grasses, C Cabeza, R E. Brevedan, M G. Klich, M A. Varillas

IGC Proceedings (1993-2023)

Accelerated ageing and cold tests were used to determine the seed vigour of different valuable forage grasses from the temperate semiarid region of Argentina (Piptochaetium napostaense, Poa ligularis, Stipa longiglumis, Stipa tenuis, Digitaria californica, Pappophorum subbulbosum, Setaria leiantha, Sorghastrum pellitum, Trichloris crinita). In general, warm season species showed greater vigour than cool season species.

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Leaf Anatomy And Ultrastructure Of Poa Ligularis After Defoliation And Water Stress, M G. Klich, R E. Brevedan, S C. Villamil Apr 2024

Leaf Anatomy And Ultrastructure Of Poa Ligularis After Defoliation And Water Stress, M G. Klich, R E. Brevedan, S C. Villamil

IGC Proceedings (1993-2023)

The objective of this study was to determine the effect of defoliation and water stress on leaf anatomy and the mesophyll cell ultrastructure of Poa ligularis. Anatomical differences were detected mainly at epidermal level. Under water stress, leaf roughness was enhanced since the epidermal-cell surface contours became conspicuous. Under defoliation the microscopic roughness decreased as a result of fewer epicuticular wax crystals being formed. Defoliation produced an enhancement of the interlamellar spaces in the irrigated plantís chloroplast. Under no defoliation conditions, chloroplast structure was not affected by water stress. When subjected to water stress, lightly defoliated plants presented chloroplasts …

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Effects Of Water Stress On Germination And Seedling Growth Of Lovegrass Species, R E. Brevedan, M G. Klich, E E. Sanchez Apr 2024

Effects Of Water Stress On Germination And Seedling Growth Of Lovegrass Species, R E. Brevedan, M G. Klich, E E. Sanchez

IGC Proceedings (1993-2023)

Seeds of seven cultivars of lovegrass species Ermelo, Morpa and Tanganyika weeping lovegrass (Eragrostis curvula var. curvula, Don Eduardo INTA (E. curvula var. robusta), Cochise lovegrass (E. lehmanniana x E. trichophera), A-68 Lehmann lovegrass (E. lehmanniana Nees) and Catalina boer lovegrass (E. curvula var. conferta) were germinated at different water potentials. Total germination percentage differed within cultivars according to water availability, although there were no great differences between the germination of the cultivars within any given water potential. The only exception was Don Eduardo INTA which had lower germination values. A marked …

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Leaf Growth And Anatomy During Winter Droughting Of Tetrachne Dregei Plants, M G. Klich, R E. Brevedan, H Laborde Apr 2024

Leaf Growth And Anatomy During Winter Droughting Of Tetrachne Dregei Plants, M G. Klich, R E. Brevedan, H Laborde

IGC Proceedings (1993-2023)

The purpose of this work was to study the leaf growth and anatomy of Tetrachne dregei plants when they were subjected to a winter drought period. Plants were grown in semicontrolled conditions under two soil moisture regimes: irrigated and non-irrigated. Anatomical characterization was made using optical and scanning electron microscopy. No differences were found in stomatal index, stomatal length and epidermal cell size, between irrigated and non-irrigated plants. The adaxial epidermis of water stressed plants was more pubescent. Leaf abaxial epidermis of non-irrigated plants showed more intercostal plates of crystallized epicuticular wax than that of the irrigated ones. Leaf tissue …

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The Interaction Between Root Distribution And Pasture Growth During Water Deficit, D J. Barker, N Dymock Apr 2024

The Interaction Between Root Distribution And Pasture Growth During Water Deficit, D J. Barker, N Dymock

IGC Proceedings (1993-2023)

Quantification of water-limited pasture growth is of interest in agriculture since it allows prediction of impaired animal production during drought, and is the basis for scheduling irrigation. Experimental work on two dairy pastures 25 km south-west of Palmerston North, New Zealand found 50% of root mass was in the top 2.3 cm of soil. Soil moisture was, similarly, not uniformly distributed down the soil profile and dried most rapidly in the top 20†cm of soil. Leaf appearance rate was more strongly correlated with water status nearer the soil surface (r = 0.52 & 0.63 for 0-5 & 10-15 cm depth, …

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Effects Of Phytohormone On Lateral Bud Elongation And Acidinvertase Activity During The Regrowth Of Sorghum Bicolor M., H Nojima, Y Takasaki, A Isoda Apr 2024

Effects Of Phytohormone On Lateral Bud Elongation And Acidinvertase Activity During The Regrowth Of Sorghum Bicolor M., H Nojima, Y Takasaki, A Isoda

IGC Proceedings (1993-2023)

The relationships of phytohormone and sucrose metabolism in the stem ofoesorghum after cutting were studied using the stem disks treated with various plantoegrowth regulators The release of buds after incubating was accelerated by 6-benzyladenoprine riboside (6- BAR) treatment. But, on abcisic acid (ABA) andoeindole acetic acid (IAA ) treatment the release of buds was retarded. The length ofoeelongated buds on all hormonal treatments was shorter than the non-treated at the end of incubated period tested. Invertase activities were stimulated on all hormonal treatments. On 6-BAR treatment, invertase activities were the highest. But there were no relationships between invertase activities and …

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Management Of Tall Wheatgrass Based On The Leaf Appearance During Spring, S Laplace, M A. Brizuela, M S. Cid Apr 2024

Management Of Tall Wheatgrass Based On The Leaf Appearance During Spring, S Laplace, M A. Brizuela, M S. Cid

IGC Proceedings (1993-2023)

The objectives of this study were to determine the date of transition from vegetative to reproductive stage at different defoliation frequencies in tall wheatgrass (Thinopyrum ponticum). In addition, we assessed the relationship between the spring temperatures and the rate of leaf appearance. To meet both objectives we had defoliated and undefoliated plant plots at Balcarce Experiment Station, Argentina. The different defoliation treatments (every 7, 14, 21 and 28 days) delayed or avoided the manifestation of the reproductive stage. The apexes of undefoliated plants began to rise on October 12, while defoliated ones slowed that elevation or the same …

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Movement Of Allelopathic Compound Coumarin From Plant Residue Of Sweet Vernalgrass (Anthoxanthum Odoratum L.) To Soil, Yoshito Yamamoto Apr 2024

Movement Of Allelopathic Compound Coumarin From Plant Residue Of Sweet Vernalgrass (Anthoxanthum Odoratum L.) To Soil, Yoshito Yamamoto

IGC Proceedings (1993-2023)

This study investigated the movement of coumarin, an allelopathic compound, from the plant residue of sweet vernalgrass (Anthoxanthum odoratum L.) to soil, as well as the dynamics of coumarin in soil. The level of coumarin dissolved from sweet vernalgrass plant residue in both Andosols and Cambisols, which were watered every day, peaked on the 5th day after the beginning of watering, and fell gradually with each additional of day. Specifically, the coumarin content in Cambisols on the 5th day was 14.2 ppm, which is 4 times the coumarin level found in Andosols. The recovery percentage of coumarin extracted with …

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Partitioning Of Phosphorus In White Clover Populations With Different Nodulation Patterns, J R. Crush Apr 2024

Partitioning Of Phosphorus In White Clover Populations With Different Nodulation Patterns, J R. Crush

IGC Proceedings (1993-2023)

The objective of this study was to see if a white clover (Trifolium repens L.) population selected for development of relatively few, but large nodules, differed in the way it used absorbed phosphorus, compared to a white clover population selected for many small nodules. Plants of both populations were grown in minus-nitrogen sand culture and the dry weights and phosphorus contents of shoots, roots and nodules were measured. There were no differences in growth or partitioning of dry matter or phosphorus between the clover lines.

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Winter Survival And Physiology Of Contrasting Fall Dormancy Selections Of Alfalfa, J J. Volenec, S M. Cunningham, L R. Teuber Apr 2024

Winter Survival And Physiology Of Contrasting Fall Dormancy Selections Of Alfalfa, J J. Volenec, S M. Cunningham, L R. Teuber

IGC Proceedings (1993-2023)

Our objective was to determine the physiological changes that accompany selection from within a germplasm for contrasting fall dormancy reaction. Selection for greater fall dormancy improved winter survival of CUF 101 from 1 to 93%. The more fall dormant CUF 101 had higher sugar concentrations in buds and roots. Roots of the more fall dormant CUF 101 also contained higher soluble protein concentrations when compared to the other CUF 101 germplasms. Root protein extracts obtained in Dec. from the more fall dormant CUF 101 contained at least one polypeptide not found in protein extracts of the other CUF 101 germplasms. …

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Root Nitrogen Cycling And Alfalfa Stress Tolerance, J J. Volenec, B C. Joern, L D. Barber, S M. Cunningham, A Ourry Apr 2024

Root Nitrogen Cycling And Alfalfa Stress Tolerance, J J. Volenec, B C. Joern, L D. Barber, S M. Cunningham, A Ourry

IGC Proceedings (1993-2023)

Our hypothesis is that certain root N pools are utilized preferentially during the early shoot regrowth. Our objective was to determine the relative contribution of crown N, root N, and specific root N pools to shoot regrowth after defoliation. We used 15N to follow N into and out of crowns, roots, and specific root N pools, to regrowing shoots after defoliation. The low molecular weight N pool (amino acids, inorganic N,...) acquired 15N rapidly within 2 d of N application. Movement of 15N into the protein-N and insoluble-N pools was delayed initially, but continued until 8 d after N application. …

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Phyllochron Development In Cool-Season Forage Grasses, A B. Frank, J D. Berdahl, J F. Karn Apr 2024

Phyllochron Development In Cool-Season Forage Grasses, A B. Frank, J D. Berdahl, J F. Karn

IGC Proceedings (1993-2023)

The purpose of this study was to evaluate the relationship between grass leaf insertion rate and accumulated growing degree-days, and determine the phyllochron for five perennial forage grass species and two cultivars of each species. Species field seeded in solid stands were crested wheatgrass [Agropyron desertorum (Fisch. ex. Link) Schult.], intermediate wheatgrass, [Thinopyrum intermedium Barkw. & Dewey:Syn:A. intermedium (Host) Brauv], western wheatgrass [Pascopyrum smithii (Rybd) L ve], green needlegrass (Stipa viridula Trin.), and smooth bromegrass (Bromus inermis Leyss). Species phyllochron differences ranged from 77 GDD for Mandan 404 smooth bromegrass to 114 GDD for Lodorm …

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Response To Drought Of White Clover Lines Selected For Different Stolon Morphologies, H D. Karsten, J R. Caradus, D R. Woodfield Apr 2024

Response To Drought Of White Clover Lines Selected For Different Stolon Morphologies, H D. Karsten, J R. Caradus, D R. Woodfield

IGC Proceedings (1993-2023)

White clover (Trifolium repens L.) lines were selected from within large and small-leaved cultivars of Grasslands Kopu and Grasslands Tahora, respectively, for long or short internodes, and for high or low branching frequency from plants grown in sun and shade (50% full sunlight). Lines were compared for drought tolerance in a perennial ryegrass (Lolium perenne L.) sward in boxes. Prior to imposing drought branching frequency selections did not differ in branching frequency, although the low branching frequency selection had a higher percentage of rooted nodes. After an imposed drought treatment sun-selected lines grew better than shade-selected lines relative …

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Kentucky Bluegrass Floral Induction And Cultivar Response To Mechanical Removal Of Harvest Residue, G A. Murray, J B. Swensen Apr 2024

Kentucky Bluegrass Floral Induction And Cultivar Response To Mechanical Removal Of Harvest Residue, G A. Murray, J B. Swensen

IGC Proceedings (1993-2023)

Open-field burning of post-harvest residue from Kentucky bluegrass (Poa pratensis L.) seed fields is being phased out in Washington, USA and may be banned in Idaho. Burning encourages early fall regrowth and timely completion of fall floral induction. Cultivars have different floral induction requirements and respond differently to mechanical residue removal. Our objective was to determine if length of fall floral induction requirement was related to seed yield when post-harvest residue was removed by crewcut vacuum sweeping. Floral induction requirements were not related to first-or second-year seed yields. Third-year seed yield of cultivars with long floral induction requirements declined …

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The Influence Of Intensity Of Tree Thinning On The Redistribution Of Soil Water In Southern African Mopani Veld, G N. Smit, N F.G. Rethman, A Moore, A Le Roux, J S. Swart Apr 2024

The Influence Of Intensity Of Tree Thinning On The Redistribution Of Soil Water In Southern African Mopani Veld, G N. Smit, N F.G. Rethman, A Moore, A Le Roux, J S. Swart

IGC Proceedings (1993-2023)

The investigation was conducted on a densely wooded area in the Mopani veld of South Africa. Six plots were subjected to different intensities of tree thinning, ranging from a totally cleared plot (0 %) to plots thinned to the equivalent of 10%, 20%, 35%, 50% and 75% of the leaf biomass of a control plot (100%). Soil water measurements were taken at six different depths to a depth of 825 mm. The infiltration of rain water and redistribution within the soil profile exhibited marked differences between experimental plots. The soil water was predominantly held at a very shallow depth ( …

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Relationship Of Visual And Quantitative Methods Of Grass Sward Development, R B. Mitchell, L E. Moser, K J. Moore Apr 2024

Relationship Of Visual And Quantitative Methods Of Grass Sward Development, R B. Mitchell, L E. Moser, K J. Moore

IGC Proceedings (1993-2023)

The objective of this study was to determine the relationship between visual and quantitative estimates of the morphological development of perennial grass swards. Pure stands of intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey] and switchgrass (Panicum virgatum L.) were hand-clipped to ground level at 2-wk intervals in 1991 at Mead, NE, morphologically classified as mean stage count (MSC), and visually estimated for sward development. Visual estimations of sward development for both species were representative of quantitative measurements during vegetative growth. However, as sward development advanced to the elongation and heading stages, visual methods over-estimated the population …

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Morphological Development Rates Of Perennial Forage Grasses, R B. Mitchell, L E. Moser, K J. Moore, D D. Redfearn Apr 2024

Morphological Development Rates Of Perennial Forage Grasses, R B. Mitchell, L E. Moser, K J. Moore, D D. Redfearn

IGC Proceedings (1993-2023)

The objective of this study was to determine the rate of change in the morphological development of switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman). Pure stands of each species were sampled at weekly intervals in 1990 and 1991 at Mead, NE, and morphologically classified as mean stage count (MSC) and mean stage weight (MSW). Linear day of the year equations accounted for 94% of the variation in switchgrass MSC and MSW. Switchgrass MSC and MSW increased at an average rate of 0.0204 and 0.0234 units per day, respectively. Linear day of the year equations accounted …

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