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Eurasian Soil Science - The differences between eutrophic peat soils (Hypereutric Sapric Histosols) and peaty gleyzems (Eutric Histic Gleysols) 20 years after a forest-peat fire have been studied... 相似文献
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T. T. Efremova A. F. Avrova S. P. Efremov N. V. Melent’eva 《Eurasian Soil Science》2009,42(10):1120-1129
In the litters (peaty, weakly decomposed, and strongly decomposed) of bog birch forests, the biochemical transformation of
plant material includes several discrete stages. The best prediction of the decomposition stages is the set of indices characterizing
the humus status of the soils: the C/N ratio, (ΣHA + ΣFA)/Cpolysaccharides, and the contents of humic and fulvic acids of fraction 1 in the groups of plant debris of different sizes. The discrimination
of the litters according to the level of the biochemical transformation of the organic residues was observed when using the
(ΣHA + ΣFA)/Cpolysaccharides ratio, which is 6.3 in the peaty litter and 11.2 and 18.4 in the weakly decomposed and strongly decomposed litters, respectively.
The biochemical classification of litters in the bog birch forests is in agreement with the morphological classification of
litters. 相似文献
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S. C. Whisson A. O. Avrova P. C. Boevink M. R. Armstrong Z. A. Seman I. Hein P. R. J. Birch 《Potato Research》2011,54(4):325-340
Late blight disease of potato, caused by Phytophthora infestans, is the most serious disease of this crop on a global scale and is thus a threat to food security. Use of resistant potato
cultivars to prevent late blight does not have a very successful history, as P. infestans genotypes have overcome the deployed resistances. Thus, there is a need to identify more durable resistances, or identify
and develop novel forms of resistance that exploit vulnerabilities in the biology of P. infestans. Application of molecular biology tools in P. infestans research has recently culminated in the identification of several avirulence effectors matching specific resistances in potato,
the sequencing of the P. infestans genome and identification of hundreds of candidate translocated pathogen ‘RXLR’ effector proteins that may promote disease
progression. Strategies for prioritising these effectors for further research are revealing those that are highly expressed
during infection, difficult for the pathogen to alter rapidly, essential for P. infestans pathogenesis and recognized by resistant accessions of Solanum spp. These effector characteristics are being used to identify and characterise resistances from Solanum germplasm that may prove more durable. In addition to RXLR effectors, P. infestans also produces a broad spectrum of additional secreted proteins. These are exposed to plant cells and may potentially act
to trigger resistance, either as broad spectrum pathogen-associated molecular patterns or as specific effectors of resistance.
Alternatively, conserved secreted proteins may be attractive targets for novel agrichemical development. We have silenced
a diverse selection of these candidate secreted proteins in P. infestans and demonstrated their effects on late blight disease development. Results from these studies are aiding a deeper understanding
of P. infestans disease development and identifying potential pathogen weaknesses for exploitation in future control measures. 相似文献
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A typological series of native Betula pubescens Ehrh. dendrocenoses along the channel of a river crossing a bog was studied. The variability of the mineral element reserves is described by geostatistical methods as the sum of a trend, autocorrelation, and random components. The contribution of deterministic and random components has been assessed in the years with average precipitation and in the year of 2007 with high and long-term flooding. The empirical variograms and the parameters of the model variograms are presented. The class of the spatial correlation of the ash reserves is described. A primary cause of the ash content’s variability is the specific water regime, which is determined by the following: (i) the abundance and duration of the spring floods responsible for the silt mass brought by the river and (ii) the draining effect of the intrabog river, the distance from which provided the formation in the forest of the ground cover with the specific species composition and ash content. The falloff of the arboreal layer in the bog birch forests formed the fundamental mineral background of the litter. 相似文献
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A formalized arrangement of morphogenetic types of litter according to the physicochemical parameters provided their significant
grouping in three genetic associations. The litter group (highly decomposed + moderately decomposed) is confined to the tall-grass
group of bog birch forests. The rhizomatous (roughly decomposed) litter is formed in the sedge-reed grass bog birch forests.
The litter group (peaty + peatified + peat) is associated with the bog-herbaceous-moss group of forest types. The genetic
associations of the litters (a) reliably characterize the edaphic conditions of bog birch forests and (b)correspond to formation
of the peat of certain ecological groups. We found highly informative the acid-base parameters, the exchangeable cations (Ca2+ + Mg2+) and the total potential acidity, which differentiated the genetic associations of litter practically with 100% probability.
The expediency of studying litters under groups of forest types rather than under separate types of bog birch forests was
demonstrated. 相似文献
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Efremova T. T. Efremov S. P. Melent’eva N. V. Avrova A. F. 《Eurasian Soil Science》2019,52(8):892-902
Eurasian Soil Science - Cryogenic oligotrophic (Hyperdystric Cryic Fibric Histosols), oligomesotrophic (Dystric Fibric Histosols), mesoeutrophic (Oligeoeutric Fibric Histosols), and eutrophic... 相似文献
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The approaches of multivariate statistics have been used for the numerical classification of morphogenetic types of moss litters in swampy spruce forests according to their physicochemical properties (the ash content, decomposition degree, bulk density, pH, mass, and thickness). Three clusters of moss litters— peat, peaty, and high-ash peaty—have been specified. The functions of classification for identification of new objects have been calculated and evaluated. The degree of decomposition and the ash content are the main classification parameters of litters, though all other characteristics are also statistically significant. The final prediction accuracy of the assignment of a litter to a particular cluster is 86%. Two leading factors participating in the clustering of litters have been determined. The first factor—the degree of transformation of plant remains (quality)—specifies 49% of the total variance, and the second factor—the accumulation rate (quantity)— specifies 26% of the total variance. The morphogenetic structure and physicochemical properties of the clusters of moss litters are characterized. 相似文献
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Dale R. Walters Anna Avrova Ian J. Bingham Fiona J. Burnett James Fountaine Neil D. Havis Stephen P. Hoad Gareth Hughes Mark Looseley Simon J. P. Oxley Alan Renwick Cairistiona F. E. Topp Adrian C. Newton 《European journal of plant pathology / European Foundation for Plant Pathology》2012,133(1):33-73
Barley is one of the world??s most important crops providing food and related products for millions of people. Diseases continue to pose a serious threat to barley production, despite the use of fungicides and resistant varieties, highlighting the impact of fungicide resistance and the breakdown of host plant resistance on the efficacy of control measures. This paper reviews progress towards an integrated approach for disease management in barley in which new methods may be combined with existing measures to improve the efficacy of control in the long-term. Advances have been made in genetic mapping of resistance (R) genes and in identifying novel sources of genes in wild barley populations and land races. Marker assisted selection techniques are being used to pyramid R genes to increase the durability of resistance. Elicitors to induce host resistance used in combination with fungicides can provide effective disease control in the field and could delay the evolution of fungicide insensitivity. Traits that may contribute to disease tolerance and escape have been identified and the extent of genetic variation within barley germplasm is being determined. Tools are being developed to integrate the above methods via an assessment of the risk of economic injury occurring from disease to guide decisions on the requirement for fungicide treatment. Barriers exist to the adoption of integrated management approaches from growers and end-users further down the supply chain (e.g. acceptance of variety mixtures) and policy incentives from government may be required for it to be taken up in practice. 相似文献
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