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Schmitt J Schneider R Elsig J Leuenberger D Lourantou A Chappellaz J Köhler P Joos F Stocker TF Leuenberger M Fischer H 《Science (New York, N.Y.)》2012,336(6082):711-714
The stable carbon isotope ratio of atmospheric CO(2) (δ(13)C(atm)) is a key parameter in deciphering past carbon cycle changes. Here we present δ(13)C(atm) data for the past 24,000 years derived from three independent records from two Antarctic ice cores. We conclude that a pronounced 0.3 per mil decrease in δ(13)C(atm) during the early deglaciation can be best explained by upwelling of old, carbon-enriched waters in the Southern Ocean. Later in the deglaciation, regrowth of the terrestrial biosphere, changes in sea surface temperature, and ocean circulation governed the δ(13)C(atm) evolution. During the Last Glacial Maximum, δ(13)C(atm) and atmospheric CO(2) concentration were essentially constant, which suggests that the carbon cycle was in dynamic equilibrium and that the net transfer of carbon to the deep ocean had occurred before then. 相似文献
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Sofie Landschoot Kevin Dewitte Bram Marynissen Veerle Derycke Joos Latr Geert Haesaert 《植物养料与土壤学杂志》2019,182(6):980-989
Tillage is an important agricultural practice, influencing the physical, chemical and biological soil characteristics. In this paper the influence of various tillage systems combined with or without a cover crop under different nitrogen fertilization levels on silage maize yield and soil fertility was investigated. Based on a field trial in Bottelare (Belgium), during the period 2007–2015, it was concluded that for each tillage system higher nitrogen levels resulted in a higher yield. In addition, the highest yield was achieved for the conventional tillage system, the yield gain for mouldboard ploughing varied between 13% (2015) and 71% (2012) compared to zero tillage. In case reduced tillage was adopted, the yield loss compared to mouldboard ploughing varied between 6% (2013 and 2015) and 24% (2012). Furthermore, it seemed that the accumulated temperature during the growing season and rainfall around flowering were decisive in determining maize yield. Additionally, rainfall in the period 60 days post sowing was significantly negatively correlated with the yield from the zero tillage plots, whereas in case tillage was adopted no correlations with rainfall 60 days post sowing were detected. Concerning the soil organic carbon content and the amount of earthworms, no clear trends could be observed. Zero tillage resulted in high weed pressure and caused soil compaction. So, in this trial, under humid conditions, the less labor intensive zero tillage system did not result in competitive maize yields. In conclusion, reduced tillage methods offer opportunities for maize cultivation in Belgium. This method of farming resulted in a lower yield, however, the difference with mouldboard ploughing was not significant. Therefore, adopting a reduced tillage system can be seen as a valid alternative for ploughing as this tillage system ensures a sustainable environment. 相似文献
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Andres D. Naiman Alejandra Latrónico Inés E. García de Salamone 《European Journal of Soil Biology》2009,45(1):44-51
Scientific evidence recognizes that the operation of a terrestrial ecosystem depends on soil microbial activity. Some Azospirillum strains produce plant growth regulators, increase the development of roots, and fix atmospheric nitrogen (N2). Some Pseudomonas strains are capable of producing cytokinins and solubilizing organic phosphorus. A sustainability analysis requires a detailed knowledge of the interrelationships between the microorganisms added to the system and those present in the soil. This study examines the effect of three commercial inoculants Azospirillum brasilense Az1 and Az2 as well as Pseudomonas fluorescens Pf on biomass production, grain yield and rhizosphere colonization of wheat, combined with two levels of N-addition. Plate counts of rhizosphere soil showed that the inoculation and N-addition did not affect the number of P. fluorescens, whereas it significantly affected the number of Azospirillum. N-addition and inoculation did not change the communities of actinomycetes and bacteria but they changed the number of fungi at the rhizosphere of wheat plants. Community-level physiological profiles of carbon-source utilization of rhizosphere soil microbial communities were changed after inoculation with Az1, Az2 and Pf depending on the phenological stage of the crop. Although no significant responses were observed, in average, PGPB inoculation increased aerial biomass by 12%, root biomass by 40% and grain yield by 16%. These increases represent important earnings for the farmer and they may help to obtain a greater sustainability of the agroecosystems. 相似文献
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Katelijn H. Lievens Ronan van Rijsbergen Frederik R. Leyns Bart J. Lambert Paul Terming Jean Swings Henk J.-P. Joos 《Pest management science》1989,27(2):141-154
A search for micro-organisms associated in high numbers with roots or leaves of corn, grapevine, chicory, soybean, sunflower, barley and sugarbeet yielded a collection of over 10 000 bacterial strains. Within this collection, antifungal strains have been selected, using direct or indirect in-vitro assays against one target fungus per crop. The target fungi were selected based on their agronomic relevance as pests. Isolates with antifungal activity were tested for their spectrum of activity against a set of phytopathogenic fungi. In 15 bacterial strains with broad-spectrum activity, belonging to the species Erwinia herbicola. Serratia plymuthica, Pseudomonas fluorescens, P. aureofaciens, P. cepacia and Bacillus subtilis, the active compounds have been identified. Bacterial strains belonging to the same taxon, but isolated from different ecological niches and/or different places in Europe, produce identical compounds. In two bacterial taxa (Erwinia and Serratia) this was reflected in a genetic conservation of the regions coding for antifungal activity. In both cases, the biosynthetic pathways proved to be genetically complex. All of the compounds identified in this study have been described previously in bacterial strains isolated from analogous or completely different ecosystems. 相似文献
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R. Van Grieken K. Gysels S. Hoornaert P. Joos J. Osan I. Szaloki A. Worobiec 《Water, air, and soil pollution》2000,123(1-4):215-228
Microanalysis of individual particles allows straightforward and advanced characterisation of environmental samples. The most obvious technique to study large microparticle populations is still electron probe X-ray microanalysis (EPXMA). Recently, technical and methodological progress has been made to remedy some of the limitations of conventional EPXMA, as, for example, in the detection of low Z-elements. Recent examples of the use of EPXMA in various environmental fields are presented, namely concerning atmospheric deposition of micropollutants and nutrients to the sea, characterisation of aerosols in the context of their effect on Global Change (remote continental and biogenic aerosols) and aerosol deposition and soiling of paintings in museums. 相似文献
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Joos F Plattner GK Stocker TF Marchal O Schmittner A 《Science (New York, N.Y.)》1999,284(5413):464-467
A low-order physical-biogeochemical climate model was used to project atmospheric carbon dioxide and global warming for scenarios developed by the Intergovernmental Panel on Climate Change. The North Atlantic thermohaline circulation weakens in all global warming simulations and collapses at high levels of carbon dioxide. Projected changes in the marine carbon cycle have a modest impact on atmospheric carbon dioxide. Compared with the control, atmospheric carbon dioxide increased by 4 percent at year 2100 and 20 percent at year 2500. The reduction in ocean carbon uptake can be mainly explained by sea surface warming. The projected changes of the marine biological cycle compensate the reduction in downward mixing of anthropogenic carbon, except when the North Atlantic thermohaline circulation collapses. 相似文献
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Broekaert WF VAN Parijs J Leyns F Joos H Peumans WJ 《Science (New York, N.Y.)》1989,245(4922):1100-1102
Rhizomes of stinging nettle contain a small-sized lectin that exhibits binding specificity toward chitin. This lectin inhibits growth of several phytopathogenic and saprophytic chitin-containing fungi in vitro. The antifungal action of the nettle lectin differs from the action of chitinases, which are a ubiquitous class of antifungal plant proteins. Moreover, the nettle lectin acts synergistically with chitinase in inhibiting fungal growth. The nettle lectin may be a promising candidate for possible applications in the genetic engineering of disease-resistant crops. 相似文献
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