Sap flow of a wild cherry tree plantation growing under Mediterranean conditions: Assessing the role of environmental conditions on canopy conductance and the effect of branch pruning on water productivity

In recent decades, wild cherry has been one of the species most widely used for reforestation in Europe. Studies aiming to select and improve trees to give them the best growth rates and wood properties have increased in response to growers’ demands. However, information relating to key physiological processes such as transpiration or stomatal conductance and to the effect of the common practice of pruning on plant–water relations is scarce. The main objective of this study was to assess the effects of environmental conditions on canopy conductance dynamics. Its secondary objective was to examine the short- and medium-term effects of branch pruning on tree transpiration, growth and derived water productivity. To this end, we measured sap flow in an experimental plantation where trees were subjected to drip irrigation and rain-fed conditions and where variables characterizing climate, soil and tree growth were also monitored. The results demonstrated that the Jarvis–Stewart approach was appropriate for studying the responses of canopy conductance to environmental factors. As well as the role of vapour pressure deficit and net radiation in controlling the daily variations of canopy conductance, the single effects of decreasing soil water content (optimum relative extractable water, REW, higher than 0.4) and increasing air temperature (optimum of 21 °C), as summer conditions approached, were correctly incorporated into the modelling exercise. Soil water content exerted the greatest control on canopy conductance for trees growing under rain-fed conditions, while air temperature did for irrigated trees. Pruning significantly reduced transpiration to about 35% when pre- and post-sub-periods were compared, but also affected annual water productivity regardless of the irrigation treatment. To assess the long-term effects of pruning on water productivity, measurements in both pruned and unpruned trees would be desirable.info:eu-repo/semantics/acceptedVersio

Determination of Rod and Cone Influence to the Early and Late Dynamic of the Pupillary Light Response.

PURPOSE: This study aims to identify which aspects of the pupil light reflex are most influenced by rods and cones independently by analyzing pupil recordings from different mouse models of photoreceptor deficiency. METHODS: One-month-old wild type (WT), rodless (Rho-/-), coneless (Cnga3-/-), or photoreceptor less (Cnga3-/-; Rho-/- or Gnat1-/-) mice were subjected to brief red and blue light stimuli of increasing intensity. To describe the initial dynamic response to light, the maximal pupillary constriction amplitudes and the derivative curve of the first 3 seconds were determined. To estimate the postillumination phase, the constriction amplitude at 9.5 seconds after light termination was related to the maximal constriction amplitude. RESULTS: Rho-/- mice showed decreased constriction amplitude but more prolonged pupilloconstriction to all blue and red light stimuli compared to wild type mice. Cnga3-/- mice had constriction amplitudes similar to WT however following maximal constriction, the early and rapid dilation to low intensity blue light was decreased. To high intensity blue light, the Cnga3-/- mice demonstrated marked prolongation of the pupillary constriction. Cnga3-/-; Rho-/- mice had no pupil response to red light of low and medium intensity. CONCLUSIONS: From specific gene defective mouse models which selectively voided the rod or cone function, we determined that mouse rod photoreceptors are highly contributing to the pupil response to blue light stimuli but also to low and medium red stimuli. We also observed that cone cells mainly drive the partial rapid dilation of the initial response to low blue light stimuli. Thus photoreceptor dysfunction can be derived from chromatic pupillometry in mouse models

Water relations and vulnerability to embolism are not related: Experiments with eight grapevine cultivars

Drought tolerance mechanisms at the leaf level have been reported for grapevines but less is known about their vulnerability to embolism caused by water stress. The objective of this experiment was to determine if there is a relationship between xylem hydraulic characteristics and drought resistance mechanisms at the leaf level. The experiment was carried out on 10-year-old plants of 8 V. vinifera cvs: 'Sauvignon Blanc', 'Chardonnay', 'Cabernet Sauvignon', 'White Grenache', 'Black Grenache', 'Alicante Bouschet', 'Tempranillo', and 'Parellada' grown under field conditions without irrigation under Mediterranean climatic conditions. Embolism vulnerability curves were drawn for each cultivar. Values of the osmotic potential at full turgor, and at the turgor loss point, and the leaf bulk modulus of elasticity were obtained from pressure-volume curves on 4 different dates, from berries at pea size until harvest. All cultivars except 'Chardonnay', which showed elastic adjustment, showed osmoregulation but different patterns in vulnerability curves were found for each cultivar. While 'Parellada', 'Tempranillo' and 'Black Grenache' proved to have the most vulnerable xylem, 'Chardonnay' and 'Sauvignon Blanc' were shown to have the least vulnerable xylem to embolism. There was no relationship between the level of vulnerability to embolism for each cultivar and the drought tolerance mechanisms at the leaf level under the environmental conditions of this experiment. &nbsp

Effect of irrigation on sap flux density variability and water use estimate in cherry (Prunus avium) for timber production: Azimuthal profile, radial profile and sapwood estimation

9 páginas.-- 7 figuras.-- 3 tablas.-- 30 referenciasInformation on tree water use in plantations for high quality wood is scarce, thus studies are needed toproperly estimate the irrigation demand of these plantations. Plant water use estimation with sap flowsensors has been used extensively. However, biases in tree sap flow estimate can arise from variationson radial and azimuthal profiles of sap flux density and also from the sapwood area considered for theup-scaling from sap flux density to sap flux. This work aimed to (1) study the spatial variations of sapflux density in cherry trees in a timber orientated plantation, (2) compare several methods to estimatesapwood depth in cherry trees and (3) to evaluate the effect of drip irrigation on these factors. The resultsshowed that most of the studied trees had decreasing radial sap flux density profiles with depth asexpected. However, the three irrigated trees of bigger sizes still showed high sap flux densities in theirinner tissues, at contrast with the rest of the trees and especially with the non irrigated ones of similarsize with values close to 20% of the sap flux density measured at 1 cm depth from cambium. On the otherhand, the different methods tested to estimate sapwood depth gave significantly different results andonly the two methods of visual identification in wood cores based on color change and measurementsof sap flux densities along the xylem radius may be considered suitable for scaling purposes. Moreover,azimuthal variation pattern was found to be random in all the studied trees, and the ranking between theaspects (north, south, east and west) was not affected by either drip irrigation or sun exposition, and thusmeasuring sap flux density in any particular aspect has been shown to be suitable to estimate the overalltree sap flux. We conclude that more studies are necessary to properly assess the radial profile of sapflux density, especially when considering the high sap flux density in the inner tissues of the three biggerirrigated trees as compared to the other trees, and also how this pattern seemed to indicate sapwooddepths values very contrasted to the ones estimated from color change in wood cores.Acknowledgments MONTES (CSD 2008-00040) projectsfunded by the Spanish Ministry of Science and Innovation. The firstauthor was the recipient of a FPI grant from the Spanish Ministryof Economy and Competitiveness. The field work of Eulalia Serra,Beatriz Grau, Marc Ferrer and Cristian Morales is highly appreci-ated.Peer reviewe

Spatio-temporal dynamics of oscillatory brain activity during the observation of actions and interactions between point-light agents

Predicting actions from non-verbal cues and using them to optimise one's response behaviour (i.e. interpersonal predictive coding) is essential in everyday social interactions. We aimed to investigate the neural correlates of different cognitive processes evolving over time during interpersonal predictive coding. Thirty-nine participants watched two agents depicted by moving point-light stimuli while an electroencephalogram (EEG) was recorded. One well-recognizable agent performed either a 'communicative' or an 'individual' action. The second agent either was blended into a cluster of noise dots (i.e. present) or was entirely replaced by noise dots (i.e. absent), which participants had to differentiate. EEG amplitude and coherence analyses for theta, alpha and beta frequency bands revealed a dynamic pattern unfolding over time: Watching communicative actions was associated with enhanced coupling within medial anterior regions involved in social and mentalising processes and with dorsolateral prefrontal activation indicating a higher deployment of cognitive resources. Trying to detect the agent in the cluster of noise dots without having seen communicative cues was related to enhanced coupling in posterior regions for social perception and visual processing. Observing an expected outcome was modulated by motor system activation. Finally, when the agent was detected correctly, activation in posterior areas for visual processing of socially relevant features was increased. Taken together, our results demonstrate that it is crucial to consider the temporal dynamics of social interactions and of their neural correlates to better understand interpersonal predictive coding. This could lead to optimised treatment approaches for individuals with problems in social interactions

Cone Genesis Tracing by the Chrnb4-EGFP Mouse Line: Evidences of Cellular Material Fusion after Cone Precursor Transplantation.

The cone function is essential to mediate high visual acuity, color vision, and daylight vision. Inherited cone dystrophies and age-related macular degeneration affect a substantial percentage of the world population. To identify and isolate the most competent cells for transplantation and integration into the retina, cone tracing during development would be an important added value. To that aim, the Chrnb4-EGFP mouse line was characterized throughout retinogenesis. It revealed a sub-population of early retinal progenitors expressing the reporter gene that is progressively restricted to mature cones during retina development. The presence of the native CHRNB4 protein was confirmed in EGFP-positive cells, and it presents a similar pattern in the human retina. Sub-retinal transplantations of distinct subpopulations of Chrnb4-EGFP-expressing cells revealed the embryonic day 15.5 high-EGFP population the most efficient cells to interact with host retinas to provoke the appearance of EGFP-positive cones in the photoreceptor layer. Importantly, transplantations into the DsRed retinas revealed material exchanges between donor and host retinas, as >80% of transplanted EGFP-positive cones also were DsRed positive. Whether this cell material fusion is of significant therapeutic advantage requires further thorough investigations. The Chrnb4-EGFP mouse line definitely opens new research perspectives in cone genesis and retina repair