Functional aspects of root architecture and mycorrhizal inoculation with respect to nutrient uptake capacity

ACESSO via B-on: http://dx.doi.org/10.1007/s00572-003-0254-5The aim of this research was to investigate theeffect of arbuscular mycorrhizal (AM) colonisation onroot morphology and nitrogen uptake capacity of carob(Ceratonia siliqua L.) under high and low nutrientconditions. The experimental design was a factorialarrangement of presence/absence of mycorrhizal fungusinoculation (Glomus intraradices) and high/low nutrientstatus. Percent AM colonisation, nitrate and ammoniumuptake capacity, and nitrogen and phosphorus contentswere determined in 3-month-old seedlings. Grayscale andcolour images were used to study root morphology andtopology, and to assess the relation between rootpigmentation and physiological activities. AM colonisationlead to a higher allocation of biomass to white andyellow parts of the root. Inorganic nitrogen uptakecapacity per unit root length and nitrogen content weregreatest in AM colonised plants grown under low nutrientconditions. A better match was found between plantnitrogen content and biomass accumulation, than betweenplant phosphorus content and biomass accumulation. It issuggested that the increase in nutrient uptake capacity ofAM colonised roots is dependent both on changes in rootmorphology and physiological uptake potential. Thisstudy contributes to an understanding of the role of AMfungi and root morphology in plant nutrient uptake andshows that AM colonisation improves the nitrogennutrition of plants, mainly when growing at low levelsof nutrients

Plant roots in heterogenous soil environment.

This study investigated relationship between root properties of seedling of grasslan plant species grown under glasshouse conditions, and their selected ecological traits, relevant mostly to adults under field conditions. I evaluated average length of exterior and interior root links, magnitude and total length of whole root system, two typological indices and the leaf area - root length ratio for seedling of 57 species. It has been used Ellenberg indicator values of soil moisture and available nitrogen for characterisation of species ecological demands, and typology of clonal growth as a characteristic of their growth strategy. Clonal types differed significantly in magnitude and topology of the seedling root systems. Links length and L:R ratio differed between species belonging to clonal types with different origin of clonal growth organs. Ecological preferences for soil moisture had no relation to root morphology, while species with different Ellenberg indicator values for available nitrogen differed in total length, magnitude, and topology of their root system. The grasses differed from the forbs in all measured root traits.Available from STL, Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi

Management of plant communities on set-aside land and its effects on earthworm communities

Plant communities of set-aside agricultural land in a European project were managed in order to enhance plant succession towards weed-resistant, mid-successional grassland. Here, we ask if the management of a plant community affects the earthworm community. Field experiments were established in four countries, the Netherlands, Sweden, the UK, and the Czech Republic. High (15 plant species) and low diversity (four plant species) seed mixtures were sown as management practice, with natural colonization as control treatment in a randomized block design. The response of the earthworrns to the management was studied after three summers since establishment of the sites. Samples were also taken from plots with continued agricultural practices included in the experimental design and from a site with a late successional plant community representing the target plant community. The numbers and biomass of individuals were higher in the set-aside plots than in the agricultural treatment in two countries out of four. The numbers of individuals at one site (The Netherlands) was higher in the naturally colonized plots than in the sowing treatments, otherwise there were no differences between the treatments. Species diversity was lower in the agricultural plots in one country. The species composition had changed from the initial community of the agricultural field, but was still different from a late successional target community. The worm biomass was positively related to legume biomass in Sweden and to grass biomass in the UK. (C) 2005 Elsevier SAS. All rights reserved

In-situ characterization of growth of isothermal ω phase in metastable β-Ti alloy TIMETAL LCB

Metastable β-Ti alloys exhibit various solid-solid phase transitions. Our study is focused on the characterization of the diffusion controlled β→ωiso phase transition. The particles of ω phase play an important part in thermomechanical treatment since they serve as heterogeneous nucleation sites for precipitation of finely dispersed particles of hexagonal α phase. The in-situ observation of the growth of particles of ω phase could be difficult by conventional techniques. However, it was shown recently that the ω phase significantly influences the elastic constants of the material, and the different forms of ω phase have different effects on the elastic anisotropy, as well as on the internal friction coefficients. Therefore, the β→ω phase transformation could be in-situ observed by the precise measurement of the tensor of elastic constants. In this contribution, we present the study of the kinetics of the β→ωiso phase transformation by resonant ultrasound spectroscopy. The polycrystalline samples of TIMETAL LCB alloy were in-situ examined by this technique during isothermal and non-isothermal ageing at temperatures up to 300 °C

Detecting local adaptation in widespread grassland species - the importance of scale and local plant community

1. Adaptation of plant populations to local environments has been shown in many species but local adaptation is not always apparent and spatial scales of differentiation are not well known. In a reciprocal transplant experiment we tested whether: (i) three widespread grassland species are locally adapted at a European scale; (ii) detection of local adaptation depends on competition with the local plant community; and (iii) local differentiation between neighbouring populations from contrasting habitats can be stronger than differentiation at a European scale. 2. Seeds of Holcus lanatus, Lotus corniculatus and Plantago lanceolata from a Swiss, Czech and UK population were sown in a reciprocal transplant experiment at fields that exhibit environmental conditions similar to the source sites. Seedling emergence, survival, growth and reproduction were recorded for two consecutive years. 3. The effect of competition was tested by comparing individuals in weeded monocultures with plants sown together with species from the local grassland community. To compare large-scale vs. small-scale differentiation, a neighbouring population from a contrasting habitat (wet-dry contrast) was compared with the ‘home’ and ‘foreign’ populations. 4. In P. lanceolata and H. lanatus, a significant home-site advantage was detected in fitness-related traits, thus indicating local adaptation. In L. corniculatus, an overall superiority of one provenance was found. 5. The detection of local adaptation depended on competition with the local plant community. In the absence of competition the home-site advantage was underestimated in P. lanceolata and overestimated in H. lanatus. 6. A significant population differentiation between contrasting local habitats was found. In some traits, this small-scale was greater than large-scale differentiation between countries. 7. Our results indicate that local adaptation in real plant communities cannot necessarily be predicted from plants grown in weeded monocultures and that tests on the relationship between fitness and geographical distance have to account for habitat-dependent small-scale differentiation. Considering the strong small-scale differentiation, a local provenance from a different habitat may not be the best choice in ecological restoration if distant populations from a more similar habitat are available

Elastic constants of Ti-15Mo single crystals and their evolution with thermal treatment

Elastic constants of single crystals of metastable β-phase of the Ti-15Mo alloy were studied by ultrasonic methods with the aim to observe the dependence of these constants on formation of isothermal ω particles. Two ultrasonic methods were applied: resonant ultrasound spectroscopy for monitoring the temperature evolution of the elastic constants, and transient grating spectroscopy for identification of the local material symmetry at a fixed temperature. Samples with different heat treatments (isothermal ageing at 300 °C and ageing under the same temperature with uniaxial [111] loading) were studied. The results prove that the isothermal omega particles always exactly follow the original cubic symmetry of the β matrix, and that the evolutions of the elastic constants of the β-ω multi-phase crystals can be reliably approximated using Hill’s homogenizing procedure, assuming cubic elastic constants of the β-phase and isotropic elastic constants representing the ω particles

Elastic constants of Ti-15Mo single crystals and their evolution with thermal treatment

Elastic constants of single crystals of metastable β-phase of the Ti-15Mo alloy were studied by ultrasonic methods with the aim to observe the dependence of these constants on formation of isothermal ω particles. Two ultrasonic methods were applied: resonant ultrasound spectroscopy for monitoring the temperature evolution of the elastic constants, and transient grating spectroscopy for identification of the local material symmetry at a fixed temperature. Samples with different heat treatments (isothermal ageing at 300 °C and ageing under the same temperature with uniaxial [111] loading) were studied. The results prove that the isothermal omega particles always exactly follow the original cubic symmetry of the β matrix, and that the evolutions of the elastic constants of the β-ω multi-phase crystals can be reliably approximated using Hill’s homogenizing procedure, assuming cubic elastic constants of the β-phase and isotropic elastic constants representing the ω particles

Potential contribution of natural enemies to patterns of local adaptation in plants

Genetic differentiation among plant populations and adaptation to local environmental conditions are well documented. However, few studies have examined the potential contribution of plant antagonists, such as insect herbivores and pathogens, to the pattern of local adaptation. Here, a reciprocal transplant experiment was set up at three sites across Europe using two common plant species, Holcus lanatus and Plantago lanceolata. The amount of damage by the main above-ground plant antagonists was measured: a rust fungus infecting Holcus and a specialist beetle feeding on Plantago, both in low-density monoculture plots and in competition with interspecific neighbours. Strong genetic differentiation among provenances in the amount of damage by antagonists in both species was found. Local provenances of Holcus had significantly higher amounts of rust infection than foreign provenances, whereas local provenances of Plantago were significantly less damaged by the specialist beetle than the foreign provenances. The presence of surrounding vegetation affected the amount of damage but had little influence on the ranking of plant provenances. The opposite pattern of population differentiation in resistance to local antagonists in the two species suggests that it will be difficult to predict the consequences of plant translocations for interactions with organisms of higher trophic levels