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Rodriguez-Calcerrada J.,Technical University of Madrid | Rodriguez-Calcerrada J.,Center cologie Fonctionnelle et Evolutive | Pardos J.A.,Technical University of Madrid | Aranda I.,Instituto Nacional Of Investigaciones Agrarias Inia
Forestry | Year: 2010

To evaluate leaf physiological mechanisms involved in plant tolerance to water deficit between sites of varying overstorey density, we investigated leaf water relations of two broadleaved oaks (Quercus petraea (Matt.) Liebl. and Quercus pyrenaica Willd.) planted within a dense Scots pine stand, in a thinned adjacent area and in a nearby gap at a Mediterranean, mid-mountain field site. Leaf water parameters were estimated in established seedlings at the end of June and August over two consecutive years by measuring pressure-volume relationships with the pressure chamber technique. Plant water status was always similar in both species, and it was lower in August than June due to lower soil moisture at the end of summer. Higher light and diurnal water deficits in the gap were associated to more negative osmotic potentials. Impacts of overstorey density on some leaf water parameters depended on the species. While Q. pyrenaica showed active osmotic adjustment across sites, seedlings of Q. petraea were unable to cope with increased water deficit by osmotic adjustment in the unthinned dense area. While Q. pyrenaica showed consistent increases in the maximum bulk modulus of elasticity (εmax) from June to August across sites, εmax decreased in the unthinned dense area for seedlings of Q. petraea. These results could reflect distinct species strategies to cope with water deficit under the low-light conditions created by a dense overstorey. Higher leaf osmotic adjustment and bulk modulus of elasticity in Q. pyrenaica seedlings at peak summer drought might confer on them a competitive advantage during establishment in dry sub-Mediterranean understories. Opening of moderate canopy gaps in dense Scots pine stands improves some leaf mechanisms involved in drought tolerance in oak seedlings. © 2010 Institute of Chartered Foresters. All rights reserved. Source

Martinez-Sala R.,Polytechnic University of Valencia | Rodriguez-Abad I.,Polytechnic University of Valencia | Diez Barra R.,Instituto Nacional Of Investigaciones Agrarias Inia | Capuz-Lladro R.,Polytechnic University of Valencia
Construction and Building Materials | Year: 2013

In the realm of architecture ground-penetrating radar has been used as nondestructive technique to assess physical properties of wood structures in situ. However, a better understanding of the dielectric anisotropy of timber is needed to develop this application. An experiment was conducted on samples of sawn timber of different species (densities) to study their dielectric responses according to the grain directions using a GPR with a 1.6 GHz antenna. Interesting differences were found: the propagation velocities, as well as the amplitudes of the direct and reflected waves always presented lesser when the electric field was longitudinal to the grain than when transverse. But when the field was propagated in whatever transverse direction some of those parameters not differ greatly. © 2012 Elsevier Ltd. All rights reserved. Source

Martin C.,Technical University of Madrid | Cervera M.T.,Instituto Nacional Of Investigaciones Agrarias Inia | Gonzalez-Benito M.E.,Technical University of Madrid
Journal of Plant Physiology | Year: 2011

Genetic stability in chrysanthemum (cultivar 'Pasodoble') apices was studied at each step of an encapsulation-dehydration cryopreservation protocol: control shoots (A), nodal segments after cold treatment (N), apices after osmotic stress (0.3 M sucrose) and cold treatment (P), encapsulation and culture in 0.8 M sucrose (S), dehydration (D), and cryopreservation (Cr). Two different markers were employed: RAPDs and AFLPs. Throughout the process, the origin of the apices (in vitro shoot from which they were excised) was recorded. Eight complete lines (from which DNA could be amplified after all the steps considered) were studied. Two out of twelve arbitrary primers showed polymorphisms. Three RAPD markers were replaced by three new ones in the Cr sample in one line. Using a different primer, a 700 bp fragment was absent from all samples from the 0.3. M sucrose-culture step ('P') onwards, in all the lines studied. The sequences of these fragments were studied to find similarities with known sequences. Polymorphic AFLP fragments were also observed, and most of the differences appeared from step 'P' onwards, pointing out the possible effect of this process (preculture on 0.3. M sucrose) in the DNA variation. These results show that genetic variation can appear throughout the cryopreservation process, and the low temperature itself is not the only stress risk of the technique. Therefore, genetic stability of the regenerants obtained after cryopreservation should be monitored. © 2010 Elsevier GmbH. Source

Rodriguez-Abad I.,Polytechnic University of Valencia | Martinez-Sala R.,Polytechnic University of Valencia | Garcia-Garcia F.,Polytechnic University of Valencia | Capuz-Lladro R.,Polytechnic University of Valencia | Diez Barra R.,Instituto Nacional Of Investigaciones Agrarias Inia
2011 6th International Workshop on Advanced Ground Penetrating Radar, IWAGPR 2011 | Year: 2011

The dielectric response of timber to electrical fields is influenced by many factors, one of the most important being the internal structure of the wood. Thus the anisotropy of the wood should be taken into account when the ground-penetrating radar (GPR) technique is used to explore the properties of timber. The work carried out analyzes, by means of a GPR with a 1.6 GHz antenna, the dielectric behavior of Maritime Pine timber according to the direction of the electrical field with respect to the grain. After the acquisition process, the propagation velocities, amplitudes, and spectra variations were compared for all the studied grain directions. Significant differences were found between these parameters when the field was propagated in a parallel direction compared with perpendicular to the grain. However, when the field was propagated in various perpendicular directions to the grain (radial & tangential) the studied parameters were not found to differ greatly. © 2011 IEEE. Source

Sanchez-Gomez D.,Instituto Nacional Of Investigaciones Agrarias Inia | Robson T.M.,University of Helsinki | Gasco A.,Instituto Nacional Of Investigaciones Agrarias Inia | Gasco A.,IE University | And 2 more authors.
Environmental and Experimental Botany | Year: 2013

Patterns of intraspecific variation in functional traits have been widely studied across plant species to find out what general suites of traits provide functional advantage under specific environmental conditions. Much less is known about this variation within tree species and, in particular, about its relationship with performance variables such as photosynthetic rates under water deficit. Nevertheless, this knowledge is fundamental to understand the adaptive potential of drought sensitive tree species to increased aridity as predicted in the context of climate change. Intraspecific variation in photosynthetic performance and other leaf functional traits in response to water availability were examined in a glasshouse experiment using seedlings of six European beech populations. The physiological response of seedlings to a "water stress" treatment was compared to a "control" treatment along an experimental cycle of progressive soil water deficit and recovery. We found evidence of intraspecific variation in beech's photosynthetic performance and other leaf functional traits in response to water availability. We also detected intraspecific variation in leaf-level tolerance of water deficit and phenotypic plasticity to water availability suggesting a pattern shaped by both regional and local scale effects. The Swedish population was particularly sensitive to water deficit, being the only population showing impaired photochemical efficiency under the experimental water deficit. Leaf-level tolerance of water deficit was related to PNUE, but not to other functional traits, such as WUE, SLA or leaf nitrogen content, that have been described to vary across species in adaptation to drought tolerance. Our results support the idea that general trends for variation in functional traits across species do not necessarily reflect a similar pattern when observed at the intraspecific level. The observed functional variation between beech populations reaffirms the importance of local adaptation to water deficit in the context of climate change. © 2012 Elsevier B.V. Source

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