Leaf water status and stem xylem flux in relation to soil drought in five temperate broad-leaved tree species with contrasting water use strategies     

Paul Köcher  Tobias Gebauer  Viviana Horna  Christoph Leuschner 《Annals of Forest Science》2009,66(1):101-101

? Five temperate broad-leaved tree species were compared with respect to their water consumption strategies under ample and restricted water supply. We measured synchronously leaf conductance (g _L) in the sun canopy, xylem sap flux (J _s) and leaf water potential (predawn, ψ_pd and noon, ψ_noon) in adult trees in a mixed stand and related them to the fluctuations in vapor pressure deficit (D) and soil moisture.

? Maximum g _L was particularly high in F. excelsior, C. betulus and T. cordata and revealed a higher D sensitivity. ψ_pd remained constantly high in A. pseudoplatanus, C. betulus and F. excelsior, but decreased in T. cordata and F. sylvatica with decreasing soil moisture.

? J _sddecreased linearly with decreasing soil matrix potential in all species except for F. excelsior. Apparent hydraulic conductance in the soil-to-leaf flow path (L _c) was higher in A. pseudoplatanus than in the other species.

? F. sylvatica maintained a low maximum g _L and reduced J _sd markedly upon drought, but faced severe decreases in ψ_pd and ψ_noon. F. excelsior represents an opposite strategy with high maximum g _L and stable ψ_pd.

? The species drought sensitivity increases in the sequence F. excelsior < C. betulus < T. cordata < A. pseudoplatanus < F. sylvatica.

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Effect of weaning initiation time and feed pellet size on peled Coregonus peled (Gmelin 1789) larviculture     

Jan Matou&#x;ek  Tatyana Gebauer  Vlastimil Stejskal 《Aquaculture Research》2020,51(5):2150-2154

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The filter-feeding bivalve Mytilus chilensis capture pelagic stages of Caligus rogercresseyi: A potential controller of the sea lice fish parasites     

Jaime A. Montory  Oscar R. Chaparro  Andres Averbuj  Luis P. Salas-Yanquin  Joseline A. Büchner-Miranda  Paulina Gebauer  Juan P. Cumillaf  Edgardo Cruces 《Journal of fish diseases》2020,43(4):475-484

The copepod Caligus rogercresseyi is an ectoparasite of several salmonid species. The pumping activity of filter-feeding molluscs could reduce the abundance of copepod dispersive larval stages in the water column. In this research, nauplius II and copepodid larvae of C. rogercresseyi were exposed to filtering mussels (Mytilus chilensis) of different sizes. These mussels were able to filter both larval stages, although they were more efficient in catching nauplius II. The fact that nauplius II were ingested more efficiently could be explained by their smaller size, lower swimming velocity (escape) and longer resting times between movements, when they were exposed to the influx of water around the inhalant area of the mussels. Larger mussels were more effective filtering C. rogercresseyi larvae due to their larger inhalant area and the related water influx. Additionally, the results suggest that larvae captured by the mussels can be incorporated into pseudofaeces or ingested and then released as part of the faeces. Thus, high concentrations of M. chilensis surrounding salmon farms may act as biological barriers, reducing the density of copepod dispersive larval stages and, thus, salmon infestations.  相似文献   

Grewia flavescens: a potential horticultural crop?     

J. Gebauer  H. Bernholt  K. Hammer 《Genetic Resources and Crop Evolution》2013,60(6):1915-1919

Traditionally agricultural research has given little attention to underutilized or neglected crops. Grewia flavescens Juss., the donkey berry, is a fruit species which is found throughout semi-arid and sub-humid tropical Africa and sometimes cultivated in homegardens. The species is also known for its ornamental value and is used as a vegetable, fodder and in basketry. In Niger its fruits are mostly collected in the wild and sold at markets. The fruits are used as food and for traditional medicinal treatments. To promote this interesting neglected taxon as a horticultural crop, information on its germplasm diversity and cultivation practices is urgently needed.  相似文献   

Contribution to the epidemiology of afflichtion with Dicrocoelium lanceolatum in sub-alpine conditions     

O Gebauer  W Hohorst 《Wiener tier?rztliche Monatsschrift》1968,55(5):382-385

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Obstbau im Sudan—unter Berücksichtigung von Wildobst     

Dr. J. Gebauer  O. A. Osman 《Erwerbs-Obstbau》2004,46(4-5):110-116

The availability of land and water resources in a diversity of climatic zones provides Sudan with a vast potential to produce many tropical and subtropical fruits. Bananas, dates, guavas, mangos, and citrus are the major fruits produced on a commercial scale. Fruit growing is mostly limited to enterprises ranging from 1–40 ha. Fruits of indigenous wild fruit species play an important role in the diet of people in the savanna belt, especially during famines and food shortages. Local varieties are grown in many fruit-producing areas. They are well adapted to the local environment but of low-to-medium market quality and productivity. Research and international cooperation are necessary and promising for future development of the fruit-producing sector in Sudan.  相似文献   

First record of baobab (Adansonia digitata L.) in Uganda     

Jens Gebauer  Cory W. Whitney  John R. S. Tabuti 《Genetic Resources and Crop Evolution》2016,63(5):755-762

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Antigen selection and presentation to protect against transmissible gastroenteritis coronavirus.   总被引：2，自引：0，他引：2  

L Enjuanes  C Su?é  F Gebauer  C Smerdou  A Camacho  I M Antón  S González  A Talamillo  A Méndez  M L Ballesteros 《Veterinary microbiology》1992,33(1-4):249-262

The antigenic structure of the S glycoprotein of transmissible gastroenteritis virus (TGEV) and porcine respiratory coronavirus (PRCV) has been determined and correlated with the physical structure. Four antigenic sites have been defined (A, B, C, and D). The sites involved in the neutralization of TGEV are: A, D, and B, sites A and D being antigenically dominant for TGEV neutralization in vitro. These two sites have specific properties of interest: site A is highly conserved and is present in coronaviruses of three animal species, and site D can be represented by synthetic peptides. Both sites might be relevant in protection in vivo. PRCV does not have sites B and C, due to a genomic deletion. Complex antigenic sites, i.e., conformation and glycosylation dependent sites, have been represented by simple mimotopes selected from a library expressing recombinant peptides with random sequences, or by anti-idiotypic internal image monoclonal antibodies. An epidemiological tree relating the TGEVs and PRCVs has been proposed. The estimated mutation fixation rate of 7 +/- 2 x 10(-4) substitutions per nucleotide and year indicates that TGEV related coronaviruses show similar variability to other RNA viruses. In order to induce secretory immunity, different segments of the S gene have been expressed using a virulent forms of Salmonella typhimurium and adenovirus. These vectors, with a tropism for Peyer's patches may be ideal candidates in protection against TGEV.  相似文献   

Gaseous emissions and soil fertility of homegardens in the Nuba Mountains,Sudan          下载免费PDF全文

Sven Goenster  Martin Wiehle  Martina Predotova  Jens Gebauer  Abdalla Mohamed Ali  Andreas Buerkert 《植物养料与土壤学杂志》2015,178(3):413-424

Intensification of homegardens in the Nuba Mountains may lead to increases in C and nutrient losses from these small‐scale land‐use systems and potentially threaten their sustainability. This study, therefore, aimed at determining gaseous C and N fluxes from homegarden soils of different soil moisture, temperature, and C and N status. Emissions of CO₂, NH₃, and N₂O from soils of two traditional and two intensified homegardens and an uncultivated control were recorded bi‐weekly during the rainy season in 2010. Flux rates were determined with a portable dynamic closed chamber system consisting of a photo‐acoustic multi‐gas field monitor connected to a PTFE coated chamber. Topsoil moisture and temperature were recorded simultaneously to the gas measurements. Across all homegardens emissions averaged 4,527 kg CO₂‐C ha^?1, 22 kg NH₃‐N ha^?1, and 11 kg N₂O‐N ha^?1 for the observation period from June to December. Flux rates were largely positively correlated with soil moisture and predominantly negatively with soil temperature. Significant positive, but weak (r_s < 0.34) correlations between increasing management intensity and emissions were noted for CO₂‐C. Similarly, morning emissions of NH₃ and increasing management intensity were weakly correlated (r_s = 0.17). The relatively high gaseous C and N losses in the studied homegardens call for effective management practices to secure the soil organic C status of these traditional land‐use systems.  相似文献   

Long-term mild hypoxia does not reduce thermal tolerance or performance of the freshwater prawn Macrobrachium tenellum     

Nelly Tremblay  Marcelo García-Guerrero  Fernando Díaz  Claudia Caamal-Monsreal  Gabriela Rodríguez-Fuentes  Kurt Paschke  Paulina Gebauer  Carlos Rosas 《Aquaculture Research》2022,53(1):63-74

The present study was designed to assess the performance of the freshwater prawn Macrobrachium tenellum in optimal and sub-optimal dissolved oxygen conditions, considering increasing environmental pressures. Thermal tolerance and thermal metabolic scope (TMS) with related integrated biomarker response (IBR) were measured in prawns exposed to normoxia (80% air saturation), mild (40% air saturation) and severe hypoxia (25% air saturation) at three exposure time points (10, 20 and 30 days). Effects of hypoxia on thermal tolerance were not detectable over time; they were perhaps masked by hyperventilation, or by an increase or diversion of haemolymph processes. After 30 days, TMS was 11% higher in mild hypoxia compared with normoxia, while it was 64% lower in severe hypoxia, indicating the loss of aerobic metabolism capacity during the latter. Mild-hypoxia prawns maintained a high IBR over time, supported by antioxidant enzyme activities (mainly superoxide dismutase), which helped avoid the serious oxidative damage (proteins and lipids) seen in severe hypoxia animals, as well as lower acetylcholinesterase activity that indicated failure of communication between the nervous and locomotor systems. Our results documented a high tolerance by M. tenellum to mild-hypoxia events, which should be further tested under seasonal and extreme habitat/tank temperatures.  相似文献