scholarly journals Morphologic, Molecular, and Pathogenic Characterization of Diaporthe phaseolorum Variability in the Core Soybean-Producing Area of Argentina

2003 ◽  
Vol 93 (2) ◽  
pp. 136-146 ◽  
Author(s):  
Rosanna N. Pioli ◽  
Eligio N. Morandi ◽  
María C. Martínez ◽  
Florencia Lucca ◽  
Alejandro Tozzini ◽  
...  
Keyword(s):  
Random Amplified Polymorphic Dna ◽  
Intraspecific Variability ◽  
Principal Component ◽  
Stem Canker ◽  
Avirulence Genes ◽  
Physiological Races ◽  
The Core ◽  
Growing Seasons ◽  
Diaporthe Phaseolorum ◽  
Soybean Genotypes

Isolates of the Diaporthe/Phomopsis (D/P) complex were collected in the main soybean producing area of Argentina during the 1996-97, 1997-98, and 1998-99 growing seasons. Twenty-three morphologic characters related to type of colonies, stroma, pycnidia and conidia, presence of perithecia, and asci length were studied by principal component analysis (PCA). Genomic DNA were analyzed by the random amplified polymorphic DNA (RAPD) technique. From both studies, 18 isolates were identified as D/P complex and grouped in four major taxa: (i) Diaporthe phaseolorum var. meridionalis, (ii) D. phaseolorum var. caulivora, (iii) D. phaseolorum var. sojae, and (iv) Phomopsis longicolla. In addition to distinguishing interspecific and intraspecific variability, molecular markers allowed the detection of differences among isolates within the same variety. Pathogenicity was assayed in the greenhouse, by the toothpick method, inoculating the D/P isolates to soybean genotypes carrying different resistance genes (Rdc1, Rdc2, Rdc3, and Rdc4) against soybean stem canker (SSC). Pathogenic analysis distinguished two main groups: (i) the SSC-producing isolates, including D. phaseolorum var. meridionalis and D. phaseolorum var. caulivora, and (ii) the non-SSC-producing isolates, including D. phaseolorum var. sojae and P. longicolla. Cultivar RA-702 (susceptible control) was compatible with both D. phaseolorum var. meridionalis and D. phaseolorum var. caulivora isolates; meanwhile, Tracy-M (Rdc1 and Rdc 2 genes) was incompatible with D. phaseolorum var. meridionalis but compatible with D. phaseolorum var. caulivora isolates. The fact that Rdc1 and Rdc2 together (as in Tracy-M) confer an almost immune reaction to all assayed isolates of D. phaseolorum var. meridionalis but were ineffective against the D. phaseolorum var. caulivora isolates evaluated suggests that the virulence or avirulence genes in D. phaseolorum var. meridionalis and D. phaseolorum var. caulivora are different. Moreover, physiological races of D. phaseolorum var. meridionalis were detected by using differential soybean genotypes carrying distinct single Rdc genes. As far as we know, this is the first report on the existence of physiological races of D. phaseolorum var. meridionalis in South America. Selective pressure due to deployment of resistant host cultivars may have changed the frequency of the virulence or avirulence genes within the population of D. phaseolorum var. meridionalis. On the whole, our results show that pathogenic variability of D. phaseolorum in the core soybean-producing area of Argentina is higher than previously recognized.

scholarly journals Occurrence of Diaporthe phaseolorum var. meridionalis on Soybean in Illinois

Plant Disease ◽  
2001 ◽  
Vol 85 (11) ◽  
pp. 1211-1211 ◽  
Author(s):  
C. E. Gravert ◽  
S. Li ◽  
G. L. Hartman
Keyword(s):  
Stem Canker ◽  
The United States ◽  
The State ◽  
Potato Dextrose Agar ◽  
Phomopsis Longicolla ◽  
Growing Seasons ◽  
Irregular Shapes ◽  
Diaporthe Phaseolorum ◽  
Northern Regions ◽  
Soybean Plants

Both Diaporthe phaseolorum var. caulivora and D.phaseolorum var. meridionalis cause stem canker on soybean, with D. phaseolorum var. caulivora reported in the northern regions and D. phaseolorum var. meridionalis reported in the southern regions of the United States (1). During the 1999 and 2000 growing seasons, fungi were isolated from soybean plants from growers' fields exhibiting stem canker symptoms. Stem tissue along the margin of the canker was cut into 1- to 5-mm3 pieces, surface-disinfected for 4 min in 0.5% NaOCl solution, rinsed twice, and plated on water or potato dextrose agar (PDA). Fungi of interest were hyphal tipped, grown on PDA at 21°C with 24 h of light, and identified by culture and spore morphology after 3 to 4 weeks. Typical D. phaseolorum var. meridionalis isolates produced white, lanose colonies that turned tan with age. Most of the D. phaseolorum var. meridionalis isolates produced pycnidia with alpha spores and beaked perithecia after 25 to 30 days (2). Brown to black stromata formed in irregular shapes. Of the 16 D. phaseolorum var. meridionalis isolates identified, 11 were from Illinois, 1 each from Indiana and Ohio, and 3 from Kentucky. In Illinois, four isolates were from the northern part of the state, and the rest were from the central and southern areas of the state. In addition to D. phaseolorum var. meridionalis, other isolates obtained from soybean plants included D. phaseolorum var. caulivora, D. phaseolorum var. sojae, and Phomopsis longicolla. References: (1) J. A. McGee and D. C. Biddle. Plant Dis. 71:620, 1987. (2) A. W. Zhang et al. Phytopathology 88:1306, 1998.

scholarly journals First Report on Pathogenic Variability of Different Isolates of Diaporthe phaseolorum var. meridionalis on Soybean in Argentina

Plant Disease ◽  
1999 ◽  
Vol 83 (11) ◽  
pp. 1071-1071 ◽  
Author(s):  
R. N. Pioli ◽  
E. N. Morandi ◽  
C. O. Gosparini ◽  
A. L. Borghi
Keyword(s):  
Resistance Genes ◽  
Stem Canker ◽  
Growing Seasons ◽  
Diaporthe Phaseolorum ◽  
Glycine Max L ◽  
Glucose Agar ◽  
Soybean Plants ◽  
Pathogenic Variability ◽  
Major Resistance Genes ◽  
Phomopsis Phaseoli

The objective of this study was to characterize the pathogenicity of several local isolates of Diaporthe phaseolorum (Cooke & Ellis) Sacc. var. meridionalis Fernández and its anamorph, Phomopsis phaseoli (Desmaz.) Sacc. meridionalis Morgan-Jones, the causal agent of southern stem canker of soybean (Glycine max (L.) Merr.), in soybean lines carrying major resistance genes. Soybean plants with typical stem canker symptoms were collected during the 1996 to 1997 and 1997 to 1998 growing seasons in the central and southern areas of Santa Fe Province, Argentina. The pathogen was isolated from the internal tissues of infected stems, cultured on potato glucose agar acidified with 0.2% lactic acid (APGA), amended with streptomycin at 100 mg/liter, and maintained in the dark at 25 ± 1°C. Isolates were characterized based on the morphology of colonies, perithecia, and pycnidia and measurement of asci, bicellular, biguttulate ascospores, and alpha conidia (1). Soybean cultivars used to assay pathogenicity included Tracy M (Rdc1 and Rdc2 genes), Isoline I (Tracy Misoline with only the Rdc1 gene), Isoline II (Tracy M isoline with only the Rdc2 gene), Crockett (Rdc3 gene), Hutchinson (Rdc4 gene), and RA 702 (susceptible cultivar). Hypocotyls of 14-day-old seedlings grown in the greenhouse were inoculated by the toothpick method. Four replicates of nine seedlings each were used. Seedlings punctured with sterile toothpicks served as controls. The experiment was repeated twice with similar results. The D. phaseolorum var. meridionalis isolates assayed and their collection locations were Dpm1 (Malabrigo), Dpm2 (Los Molinos), Dpm3 (San Justo), Dpm5 (Oliveros), Dpm6 (San Jerónimo), and Dpm7 (Clarke). Twenty-eight days after inoculation, stem canker reactions were measured as the percentage of dead plants. The pathogen was reisolated from stems of randomly chosen symptomatic plants on day 14 after inoculation. These plants were included in the calculation of the percentage of dead plants. In control plants, lesions were not detected, and mycelial growth did not occur from stem portions plated on APGA. Tracy M and RA 702 had 0 to 7% dead plants and 70 to 95% dead plants, respectively, with all assayed isolates. Cultivars with single resistance genes reacted differently to various isolates. Isolates Dpm1 and Dpm3 caused little or no stem canker (<10% dead plants) on all cultivars with resistance genes. Isolates Dpm2 and Dpm6 killed 56 and 52%, respectively, of Isoline II (Rdc2 gene) plants. Isolates Dpm2 and Dpm7 killed 25% of cv. Hutchinson (Rdc4 gene) and Isoline I (Rdc1 gene) plants, respectively. Isolate Dpm5 killed <12% of plants with genes Rdc1, Rdc2, or Rdc3. The reaction of isolate Dpm5 with Hutchinson (Rdc4 gene) was not evaluated. The pathogenic diversity of these isolates of D. phaseolorum var. meridionalis may have been induced by the wide diffusion of resistant host cultivars (2). References: (1) F. A. Fernández and R. T. Hanlin. Mycologia 88:425, 1996. (2) A. W. Zhang et al. Phytopathology 88:1306, 1998.

scholarly journals Occurrence of Soybean Stem Canker (Diaporthe phaseolorum var. meridionalis) in Wisconsin

Plant Disease ◽  
2004 ◽  
Vol 88 (5) ◽  
pp. 576-576 ◽  
Author(s):  
S. Li ◽  
N. C. Kurtzweil ◽  
C. R. Grau ◽  
G. L. Hartman
Keyword(s):  
Growth Stage ◽  
Agricultural Research ◽  
Continuous Light ◽  
Stem Canker ◽  
The United States ◽  
Single Node ◽  
Growing Seasons ◽  
Diaporthe Phaseolorum ◽  
Mist Chamber ◽  
Stem Lesions

Soybean (Glycine max) developed symptoms characteristic of stem canker during the 2000 to 2003 growing seasons in Wisconsin. Symptoms were widespread in 2003 and were associated with yield losses of ≈1% statewide and as much as 25% in individual fields. Affected plants expressed dieback of foliage beginning at growth stage R3 and progressed until the R6 growth stage. Dark brown lesions were frequently observed at a single node on the lower portion of stems of plants expressing foliage dieback. Fungi were isolated from symptomatic plants collected from seven growers' fields in Rock, Sauk, Veron, and Walworth counties and the Arlington and Marshfield Agricultural Research Stations. Stems with lesions were cut into ≈5-mm pieces, surface disinfested with a 0.5% NaOCl solution for 3 min, rinsed three times in sterile distilled water, and placed on water agar (WA) or potato dextrose agar (PDA) at pH 4.5. Hy-phal tips from colonies of interest were excised and placed on acidified PDA at 25°C under continuous light for 25 to 30 days. In addition to Diaporthe phaseolorum var. caulivora (the cause of northern stem canker), four isolates of D. phaseolorum var. meridionalis (the cause of southern stem canker) were isolated. Colonies of D. phaseolorum var. meridionalis isolates were white, lanose, and became tan with age as previously described for D. phaseolorum var. meridionalis (1). Pycnidia with alpha conidia (no beta conidia) and perithecia with 3.1 to 3.4 × 9.5 to 9.8 μm ascospores formed on oat flakes on acidified WA after 30 days. Stromata were brown to black and irregularly shaped. Four isolates of D. phaseolorum var. meridionalis were tested for pathogenicity in a controlled environment using a cut stem inoculation method (2). Stems of 3-week-old seedlings of cv. Sturdy were cut at the midpoint between the second and third node, and a PDA mycelial plug (4 mm in diameter) was placed on the surface of the cut stems. This method was used to inoculate 15 plants in three replicates for each isolate tested. Inoculated plants were placed in a mist chamber in the dark at 25°C for 4 days and later moved to a greenhouse with a 16-h photoperiod at 24 ± 3°C for 3 days. All plants challenged by this method exhibited stem lesions that were 2 to 3 cm long and of similar color to lesions observed in field-grown plants. For each isolate tested, D. phaseolorum var. meridionalis was reisolated from three randomly selected symptomatic plants. Negative controls with a PDA plug did not produce lesions. To our knowledge, this is the first report of D. phaseolorum var. meridionalis on soybean in Wisconsin. The significance of this report relates to the potential spread of D. phaseolorum var. meridionalis beyond its known southern range in the United States. References: (1) F. A. Fernandez et al. Stem Canker. Pages 33–35 in: Compendium of Soybean Diseases, 4th ed. G. L. Hartman et al., eds. The American Phytopathological Society, St. Paul, MN, 1999. (2) S. Li et al. Plant Dis. 85:1031, 2001.

scholarly journals First Report of Soybean Stem Canker Caused by Diaporthe phaseolorum var. caulivora in Argentina

Plant Disease ◽  
2001 ◽  
Vol 85 (1) ◽  
pp. 95-95 ◽  
Author(s):  
R. N. Pioli ◽  
E. N. Morandi ◽  
V. Bisaro
Keyword(s):  
Disease Incidence ◽  
Low Frequency ◽  
Principal Component ◽  
Stem Canker ◽  
Morphological Characters ◽  
Santa Fe ◽  
First Report ◽  
Soybean Seedlings ◽  
Diaporthe Phaseolorum ◽  
Soybean Plants

A soybean stem canker (SSC) outbreak caused by Diaporthe phaseolorum (Cooke & Ellis) Sacc. var. meridionalis Fernández was reported in Santa Fe, Argentina, in 1997 (3). In 1999 an isolate, which was morphologically distinct from D. phaseolorum var. meridionalis, was obtained from stems of field-grown soybean plants exhibiting SSC symptoms, at Oliveros, Santa Fe, Argentina (Lat. 32° 33′S, Lon. 60° 51′W). Disease incidence was 76% in the field where samples were collected. The pathogen was isolated in darkness at 25°C on potatoglucose agar acidified with 0.2% lactic acid (3). The isolate produced white colonies with compact and tufted mycelium that changed to yellow and light tan with age. Stromata and pycnidia were not produced. After 35 days in culture, clustered perithecia were frequently observed on stem segments. Fifty asci, five from each of 10 perithecia, and bicellular, biguttulated ascospores were measured. Ascus mean length was 26.9 ± 2.5 μm and width was 5.3 ± 0.5 μm; ascospore mean length was 8.3 ± 0.6 μm and width was 2.6 ± 0.1μm. Based on these features, the new isolate was classified as D. phaseolorum var. caulivora Athou & Caldwell (1). To further compare the new isolate with previous identified ones, a principal component analysis (PCA, SAS Systems) was performed using seven isolates of D. phaseolorum var. meridionalis, three isolates of D. phaseolorum var. sojae, and two isolates of Phomopsis longicolla. Seventeen morphological characters, all related with the color and texture of the colonies, the presence and shape of the pycnidia and conidia, the presence and type of stromata and perithecia, and the length of the asci, were compared. According to the PCA analysis, the principal characters that discriminated SSC producing isolates (D. phaseolorum var. meridionalis and D. phaseolorum var. caulivora) from non-SSC producing ones (D. phaseolorum var. sojae and P. longicolla) were the development of perithecia (r = 0.98) and low frequency stromata (r = 0.98) in D. phaseolorum var. meridionalis and D. phaseolorum var. caulivora isolates. The principal components that discriminated SSC producing isolates were the more compact and tufted aspect of the mycelia (r = 0.95) and the shorter length of the asci (r = 0.83) in D. phaseolorum var. caulivora compared with D. phaseolorum var. meridionalis. Pathogenicity trials were performed under greenhouse conditions by inoculating D. phaseolorum var. caulivora mycelia in hypocotyls of soybean seedlings by the toothpick method (2). Typical SSC symptoms were observed on susceptible plants and the pathogen was re-isolated and identified from stem portions of the first internode above the inoculation point. Pathogenicity trials were repeated twice with similar results. This is the first report of D. phaseolorum var. caulivora in Argentina and, as far as we know, in all of South America. References: (1) F. A. Fernández et al. 1999. Stem canker. Pages 32–35 in: Compendium of Soybean Diseases, 4th ed. APS Press, St. Paul, MN. (2) B. L. Keeling. Phytopathology 72:807–809, 1982. (3) R. N. Pioli et al. Plant Dis. 81:1215, 1997.

Variability among isolates of Diaporthe phaseolorum f.sp. meridionalis in different vegetative compatibility groups

1989 ◽  
Vol 67 (9) ◽  
pp. 2751-2755 ◽  
Author(s):  
R. C. Ploetz ◽  
F. M. Shores
Keyword(s):  
Growth Rates ◽  
Southeastern United States ◽  
Stem Canker ◽  
Vegetative Compatibility ◽  
Vegetative Compatibility Groups ◽  
Future Studies ◽  
Diaporthe Phaseolorum ◽  
Soybean Genotypes ◽  
Compatibility Group

Members of 1 of 29 previously described vegetative compatibility groups of Diaporthe phaseolorum f.sp. meridionalis (causal agent of soybean stem canker in the southeastern United States) predominated in epidemic populations from Alabama, Georgia, Florida, and Tennessee. Factors that might explain the prevalence of vegetative compatibility group (VCG) 1 were examined in studies with members of this and other VCGs of the pathogen. The virulence of isolates within six different VCGs on eight different soybean genotypes was similar, and variation among VCGs supported previous reports of diverse virulence in Diaporthe phaseolorum f.sp. meridionalis. Isolates within different VCGs also had similar in vitro growth rates and sensitivities to fungicides used either for controlling diseases of soybean in the Southeast (benomyl) or as an ingredient in a medium that is used to selectively isolate the pathogen (triadimefon). Since members of VCG 1 did not possess exceptional virulence, growth rates, or insensitivities to benomyl or triadimefon, the prevalence of VCG 1 could not be explained by these factors. However, relating these and other characteristics of Diaporthe phaseolorum f.sp. meridionalis to a biologically significant characteristic such as vegetative compatibility would provide a logical framework by which isolates and populations of the pathogen could be evaluated in future studies.

An Input–Process–Output Model of Pilot Core Competencies

2017 ◽  
Vol 7 (2) ◽  
pp. 78-85 ◽  
Author(s):  
Heikki Mansikka ◽  
Don Harris ◽  
Kai Virtanen
Keyword(s):  
Path Analysis ◽  
Team Performance ◽  
Core Competencies ◽  
Core Competency ◽  
Principal Component ◽  
Analysis Model ◽  
Input Process ◽  
The Core ◽  
Performance Framework ◽  
Process Output

Abstract. The aim of this study was to investigate the relationship between the flight-related core competencies for professional airline pilots and to structuralize them as components in a team performance framework. To achieve this, the core competency scores from a total of 2,560 OPC (Operator Proficiency Check) missions were analyzed. A principal component analysis (PCA) of pilots’ performance scores across the different competencies was conducted. Four principal components were extracted and a path analysis model was constructed on the basis of these factors. The path analysis utilizing the core competencies extracted adopted an input–process–output’ (IPO) model of team performance related directly to the activities on the flight deck. The results of the PCA and the path analysis strongly supported the proposed IPO model.

Economic optimum plant density of irrigated early-maturity soybean in southern Alberta

2021 ◽  
Author(s):  
Tram T.N. Thai ◽  
Danny G. Le Roy ◽  
Manjula S. Bandara ◽  
James E. Thomas ◽  
Francis J Larney
Keyword(s):  
Plant Density ◽  
Profit Maximization ◽  
Seeding Density ◽  
Early Maturity ◽  
Growing Seasons ◽  
Southern Alberta ◽  
Soybean Genotypes ◽  
Glycine Max L ◽  
The Difference ◽  
Lower Plant

With soybean [Glycine max (L.) Merr.] seed cost increasing in Alberta, understanding economic optimum plant density (EOPD) could help growers save on input expenses. A study was conducted at two irrigated locations in southern Alberta (Bow Island and Lethbridge), in three growing seasons (2014–16), using two maturity group (MG) 00 soybean genotypes, two row spacings (RS; narrow, 17.5 cm; wide, 35 cm), and three seeding densities (SD; 30, 50 and 80 seeds m-2). Exponential plant density-yield relationships were used to estimate EOPD. The earlier MG 00.4 genotype compensated yield at lower plant density (39 vs. 43 plants m-2) and emergence (74 vs. 80%) than the later MG 00.8 genotype. The EOPD gaps between environments, genotypes, and RS were minimal (from 1–3 plants m-2), resulting in only 1.3–2.0% differences in grain yield (37–56 kg ha-1), and gross revenue at EOPD ($16–24 ha-1). The overall EOPD estimate was 46 plants m-2, regardless of environment, genotype or RS. The study highlighted the difference between agronomic production and profit maximization in choosing an optimum plant density, and the need to establish a seeding density calculator for irrigated soybean in southern Alberta.

scholarly journals Response of Soybean Pathogens to Glyceollin

2010 ◽  
Vol 100 (9) ◽  
pp. 897-903 ◽  
Author(s):  
Anatoly V. Lygin ◽  
Curtis B. Hill ◽  
Olga V. Zernova ◽  
Laura Crull ◽  
Jack M. Widholm ◽  
...  
Keyword(s):  
Hairy Root ◽  
Degradation Products ◽  
Macrophomina Phaseolina ◽  
Phytophthora Sojae ◽  
Plant Diseases ◽  
Phialophora Gregata ◽  
Diaporthe Phaseolorum ◽  
Significant Difference ◽  
Transformed Hairy Root ◽  
Soybean Genotypes

Plants recognize invading pathogens and respond biochemically to prevent invasion or inhibit colonization in plant cells. Enhancing this response in crop plants could improve sustainable methods to manage plant diseases. To enhance disease resistance in soybean, the soybean phytoalexin glyceollin was assessed in soybean hairy roots of two soybean genotypes, Spencer and PI 567374, transformed with either soybean isoflavone synthase (IFS2) or chalcone synthase (CHS6) genes that were inoculated with the soybean pathogens Diaporthe phaseolorum var. meridionales, Macrophomina phaseolina, Sclerotinia sclerotiorum, and Phytophthora sojae. The hairy-root-transformed lines had several-fold decreased levels of isoflavone daidzein, the precursor of glyceollin, and considerably lower concentrations of glyceollin induced by pathogens measured 5 days after fungal inoculation compared with the nontransformed controls without phenolic transgenes. M. phaseolina, P. sojae, and S. sclerotiorum grew much more on IFS2- and CHS6-transformed roots than on control roots, although there was no significant difference in growth of D. phaseolorum var. meridionales on the transformed hairy-root lines. In addition, glyceollin concentration was lower in D. phaseolorum var. meridionales-inoculated transformed and control roots than roots inoculated with the other pathogens. Glyceollin inhibited the growth of D. phaseolorum var. meridionales, M. phaseolina, P. sojae, S. sclerotiorum, and three additional soybean pathogens: Cercospora sojina, Phialophora gregata, and Rhizoctonia solani. The most common product of glyceollin conversion or degradation by the pathogens, with the exception of P. sojae, which had no glyceollin degradation products found in the culture medium, was 7-hydroxyglyceollin.

scholarly journals Live foraminiferal faunas (Rose Bengal stained) from the northern Arabian Sea: links with bottom-water oxygenation

2013 ◽  
Vol 10 (9) ◽  
pp. 15257-15304 ◽  
Author(s):  
C. Caulle ◽  
K. A. Koho ◽  
M. Mojtahid ◽  
G. J. Reichart ◽  
F. J. Jorissen
Keyword(s):  
Rose Bengal ◽  
Arabian Sea ◽  
Bottom Water ◽  
Principal Component ◽  
Environmental Parameters ◽  
Low Oxygen ◽  
The Core ◽  
Northern Arabian Sea ◽  
Transitional Group ◽  
Epistominella Exigua

Abstract. Live (Rose Bengal stained) benthic foraminifera from the Murray Ridge, within and below the northern Arabian Sea Oxygen Minimum Zone (OMZ), were studied in order to determine the relationship between faunal composition, bottom-water oxygenation (BWO), pore-water chemistry and organic matter (organic carbon and phytopigment) distribution. A series of multicores were recovered from a ten-station oxygen (BWO: 2–78 μM) and bathymetric (885–3010 m depth) transect during the winter monsoon in January 2009. Foraminifera were investigated from three different size fractions (63–125 μm, 125–150 μm and > 150 μm). The larger foraminifera (> 125 μm) were strongly dominated by agglutinated species (e.g. Reophax spp.). In contrast, in the 63–125 μm fraction, calcareous taxa were more abundant, especially in the core of the OMZ, suggesting an opportunistic behaviour. On the basis of a Principal Component Analysis, three foraminiferal groups were identified, reflecting the environmental parameters along the study transect. The faunas from the shallowest stations, in the core of the OMZ (BWO: 2 μM), were composed of "low oxygen" species, typical of the Arabian Sea OMZ (e.g., Rotaliatinopsis semiinvoluta, Praeglobobulimina spp. , Bulimina exilis, Uvigerina peregrina typeparva). These taxa are adapted to the very low BWO conditions and to high phytodetritus supplies. The transitional group, typical for the lower part of the OMZ (BWO: 5–16 μM), is composed of more cosmopolitan taxa tolerant to low-oxygen concentrations (Globocassidulina subglobosa, Ehrenbergina trigona). Below the OMZ (BWO: 26–78 μM), where food availability is more limited and becomes increasingly restricted to surficial sediments, more cosmopolitan calcareous taxa were present, such as Bulimina aculeata, Melonis barleeanus, Uvigerina peregrina and Epistominella exigua. Miliolids were uniquely observed in this last group, reflecting the higher BWO. At these deeper sites, the faunas exhibit a clear depth succession of superficial, intermediate and deep-infaunal microhabitats, because of the deeper oxygen and nitrate penetration into the sediment.

scholarly journals Research on key influence factors of creativity development of applied undergraduates based on PCA

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Xiangmin Ren ◽  
Jingwei Yu
Keyword(s):  
Principal Component Analysis ◽  
Influence Factors ◽  
Principal Component ◽  
Heilongjiang Province ◽  
Key Factors ◽  
Factors Affecting ◽  
The Core ◽  
Creativity Development ◽  
Teachers And Students ◽  
Core Characteristics

Abstract Creativity is one of the core characteristics of talent; for this reason, the creativity development of applied undergraduates should be one of the basic components of their education. This article gives an overview of the meaning of the creativity of applied undergraduates and makes a literature knowledge-mining and expert investigation on the factors affecting the creativity development. We obtained more than 100 influencing factors, filtered out the duplicative factors, and formed the remaining factors into a questionnaire. A survey was conducted among 1460 teachers and students of some applied undergraduates in Heilongjiang Province. By using principal component analysis (PCA) to analyse the questionnaire, the key factors that affect the creativity development of applied undergraduates are obtained, and the key factors are systematically analysed. According to the results of the analysis, the specific ways and methods of the creativity development of applied undergraduates are put forward.

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