bluuebunny/crossref_metadata_2025_split huggingface dataset:
Agronomic characteristics and nutritive value of 11 grasses grown with irrigation on a saline soil in southwestern Saskatchewan
Authors: Glover D. E. , Kielly G. A. , Jefferson P. G. , Cohen R. D. H. 
Published: April 2011

Agronomic and nutritive characteristics of 11 grasses were studied at Swift Current, Saskatchewan on a moderately saline irrigated soil: [smooth bromegrass (Bromus inermis Leyss.), meadow bromegrass (Bromus riparius Rehmann), tall wheatgrass (Elytrigia elongata (Host) Nevski), crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schult.), intermediate wheatgrass (Elytrigia intermedia (Host) Nevski), slender wheatgrass (Elymus trachycaulus (Linke) Gould ex Shinners), Altai wild ryegrass (Leymus angustus (Trin. Pilger), Russian wild ryegrass (Psathyrostachys junceus (Fisch.) Nevski), Dahurian wild ryegrass (Elymus dahuricus Turcz ex Grieseb), reed canarygrass (Phalaris arudinaceae L.) and creeping foxtail (Alopecurus arundinaceus Poir.)]. Grasses were clipped at threeleaf, heading and seed set. Yield, leaf-to-stem ratio (LSR), botanical composition (BC), crude protein (CP), phosphorus, fibre and in vitro dry matter digestibility (IVDMD) were determined. There were differences (P < 0.05) between the grasses in yield at each growth stage with smooth bromegrass and creeping foxtail having high yields and meadow bromegrass low yields at all growth stages. The BC of most target grasses was greater than 60%. Exceptions were Dahurian wild ryegrass, crested wheatgrass, tall wheatgrass and meadow bromegrass. There were few significant differences between the grasses for LSR, except that Russian and Altai wild ryegrasses and meadow bromegrass had higher LSR (P < 0.05) than the other grasses. Differences in CP, P, neutral (NDF) and acid (ADF) detergent fibres were inconsistent and small at each growth stage but CP and P declined (P < 0.05) while NDF and ADF increased (P < 0.05) with plant maturation. There were differences (P < 0.05) between years and cuts for all traits except between years for yield, BC and LSR at seed set (P > 0.05). Dry matter intake (DMI) NDF and in vivo dry matter digestibility (DMD) were determined for hay cut from each plot using sheep. The relationship between forage NDF and DMI: DMI g kg BW-1 d-1 = 86.5 – 0.09 NDF (r2 = 0.87; RSD = 1.16; P < 0.001)]
Kinetic formulation of oxygen consumption and denitrification processes in soil
Authors: Cho C. M. , Burton D. L. , Chang C. 
Published: April 2011

A kinetic expression for oxygen, nitrate, nitrite and nitrous oxide reduction in soil was developed. The formulation was based on competitive Michaelis-Menten kinetics for a steady microbial population whose respiratory activity was assumed to be constant so that the number of electrons produced per unit of time was constant. Competition among the electron acceptors was characterized by their affinity toward the electron and by their concentration. Several different values for the affinity coefficients were used to simulate the concentration of O2, NO3−, NO2−, N2O and N2 at various times. When relative magnitudes of affinity coefficients were chosen to be 100 000, 1, 100 and 0.1, for O2, NO3−, NO2− and N2O, respectively, the temporal plot of concentration showed that the disappearance of O2 and NO3− was zero order. The accumulation of NO2− was very small and it was rapidly reduced to N2O. The production rate of N2O was nearly zero order but the magnitude of the rate was rather small as opposed to the rate of disappearance of NO3−. The reduction of N2O to N2 took place only after NO3− had almost disappeared. With these competition parameters NO3− was stable in the presence of O2. The reduction of N2O was also very much retarded in the presence of NO3−. NO2− was relatively unstable, even in the presence of O2, and it was further reduced to N2O. With the relative magnitude of the chosen affinity coefficients, the kinetic formulation effectively simulated the "inhibitory" effect of O2 upon the denitrification process, and the "inhibitory" effect of NO3− and NO2− upon the reduction of N2O to N2. Key words: Oxygen consumption, denitrification, kinetics, competition
Estimates of water deficits and surpluses during the growing season in Ontario using the SWATRE model
Authors: Jong R. De , Bootsma A. 
Published: April 2011

The spatial and temporal variations in soil water play a key role when considering issues such as irrigation and drainage requirements, crop growth and yield potential and contamination of groundwater by agricultural chemicals. In this study a previously validated deterministic model was used to estimate water (evapotranspiration) deficits and surpluses during the growing season of a perennial forage crop at 14 locations in Ontario. Three different hydraulic soil profile characteristics, representing a clay, clay loam and sandy loam soil, and three different lower boundary conditions (free drainage, fixed and fluctuating water table) were considered. Seasonal deficits ranged from less than 15 mm in abnormally wet years (90% probability of exceedence) in the north, to more than 300 mm in exceptionally dry years (5% probability of exceedence) in the extreme southwest region of the province. With a water table fluctuating between 25 cm depth during the middle of April and 140 cm in early October, 28 to 49% of the evapotranspiration deficit was caused by excess water in all three soils. The flux of water at 100 cm depth, accumulated during the growing season, was used as a measure of the net amount of surplus water moving through the root zone or being extracted from the water table. This flux ranged from significant upward values in dry years in a sandy loam with a fixed water table at 120 cm depth, to downward fluxes of more than 300 mm in abnormally wet years when a fluctuating water table was present. Our simulations show important spatial and temporal interactions among soil and climatic factors and suggest that each one, including the lower boundary condition, should be properly characterized in soil water investigations. Key words: Soil water, modelling, spatial and temporal variability, forage crop
Nitrous oxide emission as affected by tillage, corn-soybean-alfalfa rotations and nitrogen fertilization
Authors: MacKenzie A. F. , Fan M. X. , Cadrin F. 
Published: April 2011

Nitrous oxide (N2O) produced from agricultural activities represents a threat to the ozone layer and economic losses. Rates and magnitudes of N2O emissions of cropping systems must be determined to establish corrective management procedures. In 1994, N2O emissions were determined with corn (ZeaMays L.) and corn-legume rotations. Continuous corn was studied on four soils, two from a long-term experiment, a Ste. Rosalie heavy clay (Humic Gleysol) and a Chicot sandy loam (Grey-Brown Podzol), at 0, 170, 285 or 400 kg N ha−1, and two from a corn rotation study, a Ste. Rosalie clay (Humic Gleysol) and an Ormstown silty clay loam (Humic Gleysol). Treatments included no-till (NT) and conventional tillage (CT), monoculture corn (CCCC), monoculture soybean; corn-soybean; and soybean-corn-alfalfa phased rotations. Nitrogen rates of 0, 90, or 180 kg N ha−1 for corn and 0, 20, or 40 kg N ha−1 for continuous soybean were used, and soybean/alfalfa following corn no fertilizer N. Rates of N2O emission were measured from closed chambers through the growing season. About 0.99 to 2.1% of N added was lost as N2O. Nitrous oxide emission increased with increased soil water content, NO3 concentration and fertilizer N rates. Emission of N2O was higher with NT than with CT, and with corn than with soybean or alfalfa. A corn system using CT, legumes in rotation and moderate fertilizer N would reduce N2O emission. Key words: Greenhouse gases, soil nitrate, tillage methods, water-filled pore space, denitrification, rotations
The rate of carbon change in agricultural soils in Canada at the landscape level
Authors: Smith W. N. , Rochette P. , Monreal C. , Desjardins R. L. , Pattey E. , Jaques A. 
Published: April 2011

The Century model [a computer simulation of the dynamics of soil organic carbon (SOC)] was used to estimate the rate of SOC change in agricultural soil in Canada. The analysis was carried out on 180 Soil Landscapes of Canada (SLC) polygons, representing 15% of the SLC polygons within agricultural regions. The analysis was stratified into soil zones and into soil textural classes. For each sampled polygon, Century was run for 1 to 5 types of crop rotations under conventional-tillage as well as no-tillage, providing that no-till was used on at least 5% of the land. From the Century simulations, it was estimated that the overall rate of SOC loss from agricultural soils in Canada for 1990 was 39.1 kg ha−1 yr−1 This implies that 1.93 Mt of SOC (7.08 Mt of CO2) was lost from agricultural soils in Canada. Compared to 1990, the SOC loss was estimated to have been greater by 11.9 kg ha−1 yr−1 in 1980 and 9.1 kg ha−1 yr−1 in 1985. The lower loss in 1990 was primarily due to the incorporation of no-till practices and reduction of summer fallow in the mid 1980s. In 1990, at the provincial level, Alberta had the highest rate of SOC loss at 74.5 kg ha−1 yr−1 followed by Manitoba with 66.1 kg ha−1 yr−1 In Ontario, Quebec, and the Atlantic Provinces the average provincial rate of SOC loss was less than 35 kg ha−1 yr−1 Higher SOC loss rates were typically found in soils with coarser texture and greater native SOC content. Key words: Carbon dioxide, greenhouse gas, Century model
Ecology, statistics, and the art of misdiagnosis: The need for a paradigm shift
Authors: Germano J D 
Published: April 2011

This paper approaches ecological data analysis from a different vantage point and has implications for ecological risk assessment. Despite all the advances in theoretical ecology over the past four decades and the huge amounts of data that have been collected in various marine monitoring programs, we still do not know enough about how marine ecosystems function to be able to make valid predictions of impacts before they occur, accurately assess ecosystem ``health,'' or perform valid risk assessments. Comparisons are made among the fields of psychology, social science, and ecology in terms of the applications of decision theory or approach to problem diagnosis. In all of these disciplines, researchers are dealing with phenomena whose mechanisms are poorly understood. One of the biggest impediments to the interpretation of ecological data and the advancement of our understanding about ecosystem function is the desire of marine scientists and policy regulators to cling to the ritual of null hypothesis significance testing (NHST) with mechanical dichotomous decisions around a sacred 0.05 criterion. The paper is divided into three main sections: first, a brief overview of common misunderstandings about NHST; second, why diagnosis of ecosystem health is and will be such a difficult task; and finally, some suggestions about alternative approaches for ecologists to improve our "diagnostic accuracy'' by taking heed of lessons learned in the fields of clinical psychology and medical epidemiology. Key words: statistical significance, Bayesian statistics, risk assessment
The effects of male and female Arceuthobium americanum (lodgepole pine dwarf mistletoe) infection on the relative positioning of vascular bundles, starch distribution, and starch content in Pinus contorta var. latifolia (lodgepole pine) needles
Authors: Chhikara Aditya , Ross Friedman Cynthia M. 
Published: April 2011

The lodgepole pine dwarf mistletoe, Arceuthobium americanum Nutt. ex Engelm., is a dioecious angiosperm that parasitizes conifers in western Canadian forests, causing significant yearly timber loss. A striking consequence of dwarf mistletoe infection is a marked reduction in the size of the needles located distal to the infection. The purpose of this work was to use microscopy, cytochemistry, and biochemical analysis to determine whether this reduction was associated with changes in needle anatomy and (or) starch content. Furthermore, we wanted to investigate whether these potential changes were affected by the gender of the infecting dwarf mistletoe plant. We developed a ratio (R) that evaluated the position of the two vascular bundles relative to the size of the needle, and found that bundles from male-infected trees were positioned significantly closer together than in needles from female-infected or uninfected trees (p < 0.05). Using the periodic acid – Schiff’s (PAS) reaction for cytochemical identification of starch in situ, we determined that needles from uninfected trees had abundant starch grains compared with needles from infected trees; colourimetric analysis for total starch content corroborated our PAS data. This is the first report of this phenomenon in lodgepole pine, and further supports the use of needle characteristics to assess tree health.
Meiotic stability of B chromosomes and production of macrospermatids in Aiolopus strepens (Orthoptera: Acrididae)
Authors: Suja J. A. , Vega C. Garcia de la , Rufas J. S. 
Published: April 2011

Four males from several Spanish natural populations of Aiolopus strepens were found to carry B chromosomes. These are short and acrocentric and are identical in the different individuals. They show mitotic instability and meiotic stability. When present in odd numbers one unpaired B is generally observed, while in even numbers they usually form bivalents. In no case were lagging B's observed. B chromosomes do not affect nucleolar expression. A significant increase in the number of macrospermatids is found in individuals with B's. This is more pronounced in follicles containing odd numbers of supernumerary chromosomes. A possible explanation based on an assumed influence of B univalents on the maintenance of intercellular connections is discussed. Key words: B chromosomes, spermiogenesis, insect cytogenetics.
Polysomy and supernumerary chromosomes in Ornithogalum umbellatum L. (Liliaceae)
Authors: Rejón C. Ruiz , Lozano R. , Rejón M. Ruiz 
Published: April 2011

One hundred bulbs of Ornithogalum umbellatum L. have been analyzed cytogenetically in one natural population collected from the Sierra Nevada of Spain. Three types of plants were identified: (i) diploid plants (2n = 18, 26%); (ii) diploid plants with a variable number of B chromosomes (1–8 B's, 40%); and (iii) polysomic plants (2n = 19–23) with or without B's (34%). B's are of two types: metacentric and acrocentric and are associated with three types of abnormalities: (i) failure of the A chromosomes to move to the poles at anaphase I; (ii) nondisjunction of some A chromosomes at anaphase II; and (iii) the occurrence of tetraploid sporocytes. The B's are isopycnotic, do not associate with the A's, and invariably occur as univalents at first meiosis but show no tendency for elimination. All members of the complement except the satellite chromosome, no. 6, have been detected in a trisomic or a tetrasomic condition. Additionally some unusual structural variants, not present in the diploid standard complement, appear in some polysomic individuals. The polysomic elements are euchromatic, stable, and they do not associate either with normal chromosomes or with B's. The polysomic elements form univalents when they are trisomic and bivalents when tetrasomic. The fact that a high frequency (94%) of the polysomic elements also carry B's suggests that these two forms of numerical variation are interrelated in origin. Key words: Ornithogalum umbellatum, polysomy, supernumerary chromosomes.
Chromosomal localization of the white gene of Lucilia cuprina (Diptera; Calliphoridae) by in situ hybridization
Authors: Bedo D. G. , Howells A. J. 
Published: April 2011

The white gene of Lucilia cuprina was mapped to trichogen polytene chromosomes using in situ hybridization. A tritium-labelled riboprobe made from the first gene cloned from this species was used with techniques modified from standard methods used for Drosophila melanogaster. Cytological data limiting the location of the white gene to a small portion of 3L and complementing the in situ results are also presented. Key words: Lucilia cuprina, white gene, in situ hybridization.
Genetic analysis of cold hardiness and dormancy in alfalfa
Authors: Perry M. C. , McIntosh M. S. , Wiebold W. J. , Welterlen Mark 
Published: April 2011

Cold hardiness and fall dormancy in alfalfa (Medicago sativa L.) are positively associated, although this relationship is not always desirable for maximum production. The purpose of this study was to determine basic genetic information about cold hardiness and dormancy utilizing six parents differing in their cold hardiness and fall dormancy and their S0 and S1 progeny. A 6 × 6 diallel analysis was conducted to determine differences in general and specific combining abilities. Parent–offspring regression analyses were used to estimate heritabilities for cold hardiness and fall dormancy. Fall dormancy was measured as plant height 42 days after a final cut in September. Cold hardiness was measured using specific conductivity of exosmolyzed electrolytes of plant root tissues subjected to −8 °C. General combining abilities were significant for specific conductivity and height. Specific combining ability was also significant for specific conductivity. Mean values for S0 cross progeny were 11 to 13% higher than midparent values. Heritability estimates based on parent–offspring regression coefficients were 1.32 for specific conductivity and 0.72 for height.Significant positive phenotypic correlations were found for specific conductivity and fall growth for all generations except for height for S1 progeny. The correlations decreased with each successive generation. Genotypic correlations were positive, large, and increasing for each generation indicating large, negative, and decreasing environmental correlations. Linkage of these two traits is suggested. Selection for cold hardiness and fall growth would be rapid with proper breeding methods, but selection for high levels of both cold hardiness and fall growth would be difficult with the cultivars used in this study. Key words: cold hardiness, dormancy, alfalfa, Medicago sativa, conductivity, fall growth, phenotypic, genotypic.
Morphology and genome analyses of interspecific hybrids of Elymus scabrus
Authors: Torabinejad J. , Carman J. G. , Crane C. F. 
Published: April 2011

Sexual, hexaploid (2n = 42) Elymus scabrus (R. Br.) A. Löve (formerly Agropyron scabrum (R. Br.) Beauv.) was used as the male parent for crossability studies and genome analysis of this Australian species. Mean number of paired chromosome arms (PA) and mean number of chromosome associations per metaphase I cell were determined for four different interspecific hybrids. Means by the female parent of each interspecific hybrid were as follows: tetraploid Elymus canadensis L., 1.17 PA and 32.76 I + 0.04 II (ring) + 1.08 II (rod) + 0.005 IV (chain) in 179 cells from four F1's; hexaploid Elymus tsukushiensis Honda, 14.13 PA and 23.48 I + 4.69 II (ring) + 4.13 II (rod) + 0.27 III + 0.01 IV (ring) + 0.01 IV (rod) in 140 cells from three F1's; tetraploid Elymus longearistatus (Boiss.) Tzvelev, 4.20 PA and 27.53 I + 0.39 II (ring) + 3.12 II (rod) + 0.15 III in 59 cells from one F1; and tetraploid Elymus semicostatus (Nees ex Steud.) A. Löve, 3.98 PA and 27.961 + 0.34 II (ring) + 2.86 II (rod) + 0.16 III + 0.04 IV (chain) in 50 cells from one F1. All F1's were completely sterile. An amphiploid of F1 E. tsukushiensis – E. scabrus was obtained by 0.1% colchicine treatment. It was partially sterile and had the expected chromosome number of 2n = ca. 84. The data were interpreted to indicate that E. scabrus lacks the S and H genomes of E. canadensis, contains the Y genome and a modification of another genome of E. tsukushiensis, and a modification of the Y genomes of E. longearistatus and E. semicostatus. These results contradict a previous report of an S and H genome composition for the Australasian wheatgrasses. Key words: apomixis, Elymus canadensis, Elymus longearistatus, Elymus semicostatus, Elymus tsukushiensis.
Differential zygotic abortion in an interspecific Lycopersicon cross
Authors: Gadish I. , Zamir D. 
Published: April 2011

Monogenic segregations of seven isozyme markers were analyzed in F2 and reciprocal backcross progenies of an interspecific hybrid between Lycopersicon esculentum and L. pennellii (LA 716). In the F2 population, four markers, which map to three different chromosomes, deviated significantly from the expected Mendelian ratios and in all cases an excess of the L. pennellii alleles was observed. In the backcrosses all the genes segregated normally. These results and the lack of effect of different gametophytic selection conditions on the deviations indicated that the elimination of L. esculentum alleles in the F2 did not occur at prezygotic stages. Three of the isozymes were assayed in mature F2 seed and revealed similar deviations to those observed in F2 plants. These findings, as well as the lower numbers of seed per fruit observed in the F2 than in the backcross (where the hybrid functioned as female parent), indicate that differential zygotic abortion is the main cause of the unequal segregations. In addition, analysis of two linkage groups in the reciprocal backcrosses revealed higher recombination frequencies on the female side. Key words: Lycopersicon esculentum, L. pennellii, unequal segregations, differential zygotic abortion, recombination.
Hybrid dysgenesis in Drosophila melanogaster: the elimination of P elements through repeated backcrossing to an M-type strain
Authors: Good Allen G. , Hickey Donal A. 
Published: April 2011

The rapid increase in the frequency of P elements in natural populations of Drosophila melanogaster has led to the suggestion that these elements can spread in nature through replicative transposition. In an attempt to model the introduction of a small number of P flies into an M population we backcrossed P flies and their offspring to M flies. Two components of dysgenesis, P element activity and P element copy number (measured by DNA hybridization), were monitored each generation. In these experiments P elements were not capable of spreading rapidly enough to maintain 30–50 copies per fly and were rapidly lost from the population. We also found that the reduction in a fly's ability to induce gonadal dysgenesis was matched by an equivalent reduction in P element copy number as measured by DNA hybridization. These results are discussed in terms of the conventional mechanisms of selection or segregation; the conclusion is that there are conditions under which P elements can be lost from a population. Key words: hybrid dysgenesis, P element, transposable elements, Drosophila.
Isolation and characterization of DNA probes from the short arm of the human X chromosome that detect restriction fragment length polymorphisms
Authors: Starr Terence , Wood Stephen 
Published: April 2011

We have isolated 30 X chromosome specific probes from a flow-sorted library enriched for the human X chromosome. Hybridization to somatic cell hybrids containing different regions of the X chromosome localized nine of these probes to Xp. After testing 185 probe–enzyme combinations, three of the Xp probes were found to detect restriction fragment length polymorphisms. Key words: DNA probe, polymorphisms (restriction), X chromosome.