A note on Ozark migrants and nonmigrants     

Nolan MF  Lasley RP  Green G  Hefferman WD 《Growth and change》1981,12(3):47-52

"This study documents the extent of the population shift in five Ozark counties in Missouri. It describes the structure of the population, compares migrants and nonmigrants on the basis of various sociological and demographic indicators, and examines the extent of agreement between migrants and nonmigrants on a number of community issues." The implications for rural areas of the phenomenon of urban-rural migration are considered  相似文献   

Genetics of resistance to five strains of turnip mosaic virus in Chinese cabbage   总被引：4，自引：0，他引：4  

S. K. Suh  S. K. Green  H. G. Park 《Euphytica》1995,81(1):71-77

Summary Inheritance of resistance to turnip mosaic virus (TuMV) strains C1, C2, C3, C4, and C5 in Chinese cabbage (Brassica campestris subsp. pekinensis) was evaluated using monoclonal antibodies. Crosses were made between a resistant line, 0–2, and four susceptible line. Seoul (SE),SSD31 (SS), Cheongbang (CH), and Yaki 1 ho (YA), to determine the inheritance of resistance of 0–2 in different genetic backgrounds. Resistance to TuMV was controlled by a single dominant gene or double dominant genes depending on the strain and cross. The resistance genes of 0–2 were modified by susceptible parents such that a single dominant gene was involved in the SS×0–2 combination, but double dominant genes in the SE×0–2 against TuMV-C3 or TuMV-C5. ELISA tests using inoculated and noninoculated leaves in the same plant suggested that the dominant resistance genes inhibit virus movement rather than virus multiplication.  相似文献   

Genetic Variation for Regenerative Response in Immature Leaflet Cultures of the Cultivated Peanut,Arachis hypogaea*     

M. H. Seitz  H. T. Stalker  C. C. Green 《Plant Breeding》1987,98(2):104-110

Forty-seven genotypes of the cultivated peanut, Arachis hypogaea L., were screened for regenerative responses of immature leaflet cultures on two media varying in the auxin: cytokinin ratio. Statistical analysis revealed significant media and genotype differences for rhizogenesis plus media differences for callus proliferation but no differences for shoot formation. When genotypes were categorized according to botanical types, differences between subspecies were observed for rhizogenesis. Cultivars of the Virginia botanical type (subspecies hypogaea) were significantly different from either the Valencia or Spanish botanical types (both subspecies fastigiata). Overall, rhizogenesis varied from 0 to 70% among all genotypes. Shoot production was low (30%) while callus proliferation was extremely high (70%).  相似文献   

Inheritance of fiber quality and lint yield in a chemically mutated population of cotton   总被引：2，自引：0，他引：2  

Andy D. Herring  Dick L. Auld  M. Dean Ethridge  Eric F. Hequet  E. Bechere  Cary J. Green  Roy G. Cantrell 《Euphytica》2004,136(3):333-339

The narrow germplasm base of the upland cotton (Gossypium hirsutum L.), grown on the Texas high plains historically, has limited improvement of fiber quality. Chemical mutagenesis and subsequent selection have helped the development of lines with improved fiber quality in cultivars adapted to this region. This study was conducted to determine the inheritance of improvements in fiber quality. M₃ lines with divergent fiber properties of micronaire, length, and strength were selected from a population of Paymaster HS 200 treated with 3% v/v ethyl methanesulfonate (EMS) for two hours. The 115 selected lines of M₄ and M₅ generation were evaluated for fiber quality and lint yield. Regression of the M₄ and M₅ on the M₃ generation, as well as the M₅ on the M₄ was used to generate narrow sense heritability coefficients. Significant variations were observed between the mutant lines in all generations except for lint yield in the M₅ (1997). The highest heritability estimates were found in fiber length (h ²= 0.29** to 0.46**). Micronaire and strength showed intermediate heritability estimates of h ²= 0.14 to 0.19, while lint yield had a very low heritability estimate of h ²= 0.03. Fiber length and strength were correlated (r= 0.58** to 0.46**) in all the three generations. The mutants identified in these studies have the potential to improve fiber quality of upland cotton without introducing alien genes that may reduce adaptation to short growing season production regions.  相似文献   

The ecology of extinction: population fluctuation and decline in amphibians     

David M Green 《Biological conservation》2003,111(3):331-343

Even among widespread species with high reproductive potentials and significant dispersal abilities, the probability of extinctions should be correlated both with population size variance and with the extent of population isolation. To address how variation in demographic characteristics and habitat requirements may reflect on the comparative risk of species decline, I examined 617 time series of population census data derived from 89 amphibian species using the normalized estimate of the realized rate of increase, ΔN, and its variance. Amphibians are demonstrably in general decline and exhibit a great range of dispersal abilities, demographic characteristics, and population sizes. I compared species according to life-history characteristics and habitat use. Among the populations examined, census declines outnumbered increases yet the average magnitudes for both declines and increases were not demonstrably different, substantiating findings of amphibian decline. This gives no support for the idea that amphibian population sizes are dictated by regimes featuring relatively rare years of high recruitment offset by intervening years of gradual decline such that declines may outnumber increases without negative effect. For any given population size, those populations living in large streams or in ponds had significantly higher variance than did populations of completely terrestrial or other stream-dwelling amphibians. This could not be related to life-history complexity as all the stream-breeding species examined have larvae and all of the wholly terrestrial species have direct development without a larval stage. Variance in ΔN was highest amongst the smallest populations in each comparison group. Estimated local extinction rates averaged 3.1% among pond-breeding frogs, 2.2% for pond-breeding salamanders, and negligible for both stream-breeding and terrestrial direct-developing species. Recoveries slightly exceeded extinctions among European pond-breeding frogs but not among North American pond-breeding frogs. Less common species had greater negative disparities between extinctions and recoveries. Species with highly fluctuating populations and high frequencies of local extinctions living in changeable environments, such pond- and torrent-breeding amphibians, may be especially susceptible to curtailment of dispersal and restriction of habitat.  相似文献   

The relevance of seral eutrophication and plant competition to the management of successional communities     

Brynmor H. Green  Ph.D. 《Biological conservation》1972

Seral and plagioclimax communities such as chalk grassland, dune grassland, and heathland, are of great conservational importance in the United Kingdom, and considerable resources are directed towards their management in nature reserves and amenity areas. It is suggested that an important feature of these communities is their low fertility, especially with respect to nitrogen, and that this is directly related to their floristic diversity. Successional changes, usually involving scrub colonization, lead to a build-up in fertility, to loss of floristic diversity, and often to a reduction in the wildlife and amenity value. The traditional forms of management practised on such communities—including grazing, burning, and mowing—probably arrest seral development partially by preventing the build-up of fertility in the ecosystem. Some examples of mineral nutrient studies are considered, and it is suggested that a greater knowledge of nutrient budgets is fundamental to the scientific management of these communities.  相似文献   

Analysis of N-nitrosoproline in raw bacon. Further evidence that nitrosoproline is not a major precursor of nitrosopyrrolidine     

T Hansen  W Iwaoka  L Green  S R Tannenbaum 《Journal of agricultural and food chemistry》1977,25(6):1423-1426

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Scientific principles for water utilization in the U.S.S.R.     

Alexander M. Green 《Water, air, and soil pollution》1974,3(2):237-248

Water resources are essential for economic and cultural development of a territory. Both economic development and the health of the people depend on the provision of pure water. Scientifically founded plans of water resources use and conservation should be based on a balance approach to the assessment of available water supply sources and, on the forecast of their interconnected change in the future in a close association with the forecast of the whole economy and culture of the studied region. In the future the main threat to the normal development of the economy and life will not be water deficiency but the conversion of rivers, lakes and other water supply sources into sewers. Therefore it is proposed that there be a complete cessation of sewage discharge (even of the so-called purified) into water supply sources while drawing up long-term water management balances.  相似文献   

Glomalin in aggregate size classes from three different farming systems     

S.F. Wright  V.S.Green  M.A. Cavigelli   《Soil & Tillage Research》2007,94(2):546-549

Glomalin was measured in soil from farming systems managed for 8 years by chisel tillage (CT), more intensive tillage for organic (ORG) production, and no tillage (NT) on Acrisols (FAO Soil Units) in the Mid-Atlantic region of the U.S. Whole soil and aggregate size classes of >2.00, 0.50–2.00 and 0.21–0.50 mm (macroaggregates), 0.05–0.21 mm (microaggregates), and <0.05 mm (fine material) were examined. Glomalin-related soil protein (GRSP) was extracted from 1-g samples (four plots per treatment) with 100 mM sodium pyrophosphate, pH 9.0, at 121 °C in three extraction cycles. Extracts were pooled and quantified by using the Bradford protein assay. Concentrations of GRSP and total carbon (C) in aggregates were linearly related across aggregate size classes for all treatments (GRSP = 0.101C + 0.56, r² = 0.95). No tillage had significantly greater whole soil GRSP than did CT or ORG (P = 0.01). Mean values for GRSP in aggregates of NT were higher than for CT or ORG aggregates by 0.53 and 0.66 mg g⁻¹ aggregates, respectively. There were no differences among treatments in GRSP concentrations in fine material. In NT the concentration of GRSP increased as aggregate size increased in contrast to the disturbed treatments, CT or ORG, where there were no differences in GRSP concentration across aggregate size fractions. Larger proportions of GRSP were distributed in macroaggregates of NT compared to CT and ORG in contrast to larger proportions in microaggregates of CT and ORG than in NT. Although soil disturbance in ORG farming is greater than for CT farming, both treatments had similar GRSP concentrations and distributions.  相似文献   

Interactions between the external mycelium of the mycorrhizal fungus Glomus intraradices and other soil microorganisms as affected by organic matter     

Annierose Albertsen  Helge Green  John Larsen 《Soil biology & biochemistry》2006,38(5):1008-1014

The influence of organic matter on the interactions between external mycelium of the arbuscular mycorrhizal (AM) fungus Glomus intraradices, the bacterium Burkholderia cepacia and other soil microorganisms was studied in a root-free sand environment. Organic matter amendment, in terms of ground barley leaves, markedly increased the growth of the external mycelium of G. intraradices as estimated both with the fatty acid biomarker 16:1ω5 and hyphal length measurements. Mycelial proliferation of G. intraradices in sand with organic matter was unaffected by both inoculation with B. cepacia and a soil filtrate containing a mixed population of indigenous microorganisms. On the other hand, in the absence of organic matter, both inoculation with B. cepacia and the soil filtrate reduced the growth of G. intraradices, as estimated with measurements of 16:1ω5. In contrast, B. cepacia inoculation increased hyphal length density of G. intraradices in the absence of organic matter. Overall, the presence of external mycelium of G. intraradices increased the bacterial biomass and counteracted a suppressive effect of B. cepacia on the growth of saprotrophic fungi.  相似文献