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Cuevas M.V.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Martin-Palomo M.J.,ETSIA | Diaz-Espejo A.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Torres-Ruiz J.M.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | And 4 more authors.
Irrigation Science | Year: 2013

We used sap flow and trunk diameter measurements for assessing water stress in a high-density 'Arbequina' olive orchard with control trees irrigated to replace 100 % of the crop water needs, and 60RDI and 30RDI trees, in which irrigation replaced ca. 60 and 30 % of the control, respectively. We calculated the daily difference for both tree water consumption (DEp) and maximum trunk diameter (DMXTD) between RDI trees and control trees. The seasonal dynamics of DEp agreed reasonably well with that of the stem water potential. We identified peculiarities on the response DEp to changes in water stressing conditions, which must be taken into account when using the index. An analysis of the water stress variability in the orchard is required for choosing the instrumented trees. The reliability of the D MXTD index was poorer than that of DEp. The maximum daily shrinkage (MDS) was not a reliable water stress indicator. © 2012 Springer-Verlag.

Morales-Sillero A.,University of Seville | Garcia J.M.,CSIC - Instituto de la Grasa | Torres-Ruiz J.M.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Montero A.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | And 2 more authors.
Agricultural Water Management | Year: 2013

Localized irrigation, which wets a part of the root zone only, is widely used in olive orchards. The effect of partial wetting of the root zone on plant performance is unknown. The aim of this work was to compare fruit and oil yields in olive trees under localized irrigation (LI treatment) to those from trees with the whole root zone under non-limiting soil water conditions (Pond treatment). The LI trees received enough water to replace the crop water needs. The study was made for three consecutive years in mature 'Manzanilla de Sevilla' olive trees growing under field conditions. Main variables were also measured in young trees of the same cultivar growing in 50. L pots. Samples from rain-fed trees were also analysed. The LI trees showed similar water status than the Pond trees, but reduced stomatal conductance. As expected, the effect of the irrigation treatments on net photosynthesis was less evident. We observed a decrease in fruit yield in the LI trees, as compared to the Pond trees, likely because of the reduced gas exchange. No differences between the LI and Pond treatments were found for fruit weight, pulp:stone ratio, volume and the longitudinal and equatorial diameters. The LI treatment did not cause detrimental effect either on total oil content or virgin olive oil yield. The phenols content was greater in the LI treatment, but the (E)-hex-2-enal, one of the major volatile compounds and most related to the positive attributes of olive oil, was lower. No significant differences with the Pond treatment were found, however, in the sensory description of the oil flavours. © 2013 Elsevier B.V.

Saiz-Jimenez C.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Miller A.Z.,University of Lisbon | Martin-Sanchez P.M.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Hernandez-Marine M.,University of Barcelona
Environmental Microbiology | Year: 2012

Lascaux Cave in France was discovered in 1940. Since being opened to visitors the cave has suffered three major microbial outbreaks. The current problem is the fast dissemination of black stains which are threatening the Palaeolithic paintings. Previous data pointed to the involvement of new fungal species in the formation of black stains on the rock walls and ceiling. However, it appears that there could be other reasons for the formation of different and extensive black stains coating the surface of the clayey sediments. Our analyses reveal that black stains on clayey sediments are mainly produced by Acremonium nepalense, a manganese oxide-depositing fungus, widely distributed in the cave. Thus, in Lascaux Cave, the black stains have a dual origin: on limestone rocks they are mainly produced by the accumulation of fungal melanins, and on clayey sediments by the biogenic deposition of black manganese oxides. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Hernandez-Santana V.,Iowa State University | Hernandez-Santana V.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Zhou X.,Iowa State University | Helmers M.J.,Iowa State University | And 4 more authors.
Journal of Hydrology | Year: 2013

Intensively managed annual cropping systems have produced high crop yields but have often produced significant ecosystem services alteration, in particular hydrologic regulation loss. Reconversion of annual agricultural systems to perennial vegetation can lead to hydrologic function restoration, but its effect is still not well understood. Therefore, our objective was to assess the effects of strategic introduction of different amounts and location of native prairie vegetation (NPV) within agricultural landscapes on hydrological regulation. The study was conducted in Iowa (USA), and consisted of a fully balanced, replicated, incomplete block design whereby 12 zero-order ephemeral flow watersheds received four treatments consisting of varying proportions (0%, 10%, and 20%) of prairie vegetation located in different watershed positions (footslope vs. contour strips). Runoff volume and rate were measured from 2008 to 2010 (April-October) with an H-Flume installed in each catchment, and automated ISCO samplers. Over the entire study period, we observed a total of 129 runoff events with an average runoff volume reduction of 37% based on the three treatments with NPV compared to watersheds with row crops. We observed a progressively greater reduction across the 3. years of the study as the perennial strips became established with the greatest differences among treatments occurring in 2010. The differences among the watersheds were attributed mainly to NPV amount and position, with the 10% NPV at footslope treatment having the greatest runoff reduction probably because the portion of NPV filter strip that actually contacted watershed runoff was greater with the 10% NPV at footslope. We observed greater reductions in runoff in spring and fall likely because perennial prairie plants were active and crops were absent or not fully established. High antecedent soil moisture sometimes led to little benefit of the NPV treatments but in general the NPV treatments were effective during both small and large events. We conclude that, small amounts of NPV strategically incorporated into corn-soybean watersheds in the Midwest US can be used to effectively reduce runoff. © 2012 Elsevier B.V.

Torres-Ruiz J.M.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Sperry J.S.,University of Utah | Fernandez J.E.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC
Physiologia Plantarum | Year: 2012

Xylem hydraulic conductivity (K) is typically defined as K = F/(P/L), where F is the flow rate through a xylem segment associated with an applied pressure gradient (P/L) along the segment. This definition assumes a linear flow-pressure relationship with a flow intercept (F0) of zero. While linearity is typically the case, there is often a non-zero F0 that persists in the absence of leaks or evaporation and is caused by passive uptake of water by the sample. In this study, we determined the consequences of failing to account for non-zero F0 for both K measurements and the use of K to estimate the vulnerability to xylem cavitation. We generated vulnerability curves for olive root samples (Olea europaea) by the centrifuge technique, measuring a maximally accurate reference Kref as the slope of a four-point F vs P/L relationship. The Kref was compared with three more rapid ways of estimating K. When F0 was assumed to be zero, K was significantly under-estimated (average of -81.4 ± 4.7%), especially when Kref was low. Vulnerability curves derived from these under-estimated K values overestimated the vulnerability to cavitation. When non-zero F0 was taken into account, whether it was measured or estimated, more accurate K values (relative to Kref) were obtained, and vulnerability curves indicated greater resistance to cavitation. We recommend accounting for non-zero F0 for obtaining accurate estimates of K and cavitation resistance in hydraulic studies. Copyright © 2012 Physiologia Plantarum.

Garcia J.M.,CSIC - Instituto de la Grasa | Cuevas M.V.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Fernandez J.E.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC
Irrigation Science | Year: 2013

The effect of two deficit irrigation (DI) strategies on fruit and oil production and quality in a 12-year-old 'Arbequina' olive orchard with 238 trees ha-1 was evaluated. The T1 treatment was a sustained DI regime (65% ETc, 2-3 irrigation events per week). The T2 treatment was a low-frequency DI (increasing stress/rewatering cycles, which consisted in withholding irrigation until fruit shrivelling and then applying a recovery irrigation providing the same amount of water that supplied in T1 for that period). As compared to full irrigation, both strategies reduced fruit production and increased the variability of fruit ripening, but favoured oil extraction. Free acidity, peroxide value, K232, K270 and sensory quality of oil were not affected by DI. Furthermore, carotenoid, chlorophyll, phenol, and oleic contents increased. The greatest phenol content and bitterness index were found in oil from T2 trees. Later harvesting caused sensory quality and tocopherol losses, although the oil synthesized in DI olives increased. © 2011 Springer-Verlag.

Villaverde J.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Posada-Baquero R.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Rubio-Bellido M.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Laiz L.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | And 3 more authors.
Journal of Agricultural and Food Chemistry | Year: 2012

The phenylurea herbicide diuron [N-(3,4-dichlorophenyl)-N,N-dimethylurea] is widely used in a broad range of herbicide formulations and, consequently, it is frequently detected as a major soil and water contaminant in areas where there is extensive use. Diuron has the unfortunate combination of being strongly adsorbed by soil organic matter particles and, hence, slowly degraded in the environment due to its reduced bioavailability. N-Phenylurea herbicides seem to be biodegraded in soil, but it must be kept in mind that this biotic or abiotic degradation could lead to accumulation of very toxic derived compounds, such as 3,4-dichloroaniline. Research was conducted to find procedures that might result in an increase in the bioavailability of diuron in contaminated soils, through solubility enhancement. For this purpose a double system composed of hydroxypropyl-β-cyclodextrin (HPBCD), which is capable of forming inclusion complexes in solution, and a two-member bacterial consortium formed by the diuron-degrading Arthrobacter sulfonivorans (Arthrobacter sp. N2) and the linuron-degrading Variovorax soli (Variovorax sp. SRS16) was used. This consortium can achieve a complete biodegradation of diuron to CO2 with regard to that observed in the absence of the CD solution, where only a 45% biodegradation was observed. The cyclodextrin-based bioremediation technology here described shows for the first time an almost complete mineralization of diuron in a soil system, in contrast to previous incomplete mineralization based on single or consortium bacterial degradation. © 2012 American Chemical Society.

Fernandez J.E.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Moreno F.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Martin-Palomo M.J.,Escuela Tecnica Superior de Ingenieria Agronomica | Cuevas M.V.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | And 2 more authors.
Environmental and Experimental Botany | Year: 2011

Sap flux (Q) and trunk diameter variation (TDV) are among the most useful plant-based measurements to detect water stress and to evaluate plant water consumption. The usefulness of both methods decreases, however, when applied to species that, like olive, have an outstanding tolerance to drought and a remarkable capacity to take up water from drying soils. Evidence shows that this problem is greater in old, big trees with heavy fruit load. Our hypothesis is that the analysis of simultaneous measurements of Q and TDV made in the same trees is more useful for assessing irrigation needs in old olive orchards than the use of any of these two methods alone. To test our hypothesis, we analysed relations between Q, TDV, midday stem water potential (Ψstem), relative extractable water and atmospheric demand in an olive orchard of 38-year-old 'Manzanilla' trees with heavy fruit load. Measurements were made during one irrigation season (May-October), in fully irrigated trees (FI, 107% of the crop evapotranspiration, ETc, supplied by irrigation), and in trees under two levels of deficit irrigation (DI60, 61% ETc; DI30, 29% ETc). Time courses of Q and TDV measured on days of contrasting weather and soil water conditions were analysed to evaluate the usefulness of both methods to assess the crop water status. We calculated the daily tree water consumption (Ep) from Q measurements. For both DI treatments we calculated a signal intensity by dividing daily Ep values of each DI tree by those of the FI tree (SI-Ep). We did the same with the maximum daily shrinkage (MDS) values (SI-MDS). Neither SI-Ep nor SI-MDS rendered useful information for assessing the crop water needs. On the contrary, the daily difference for maximum trunk diameter (MXTD) between each of the DI trees and the FI tree (DMXTD) clearly indicated the onset and severity of water stress. A similar analysis with the Ep values, from which DEp values were derived, showed the effect of water stress on the water consumption of the trees. We concluded that the simultaneous use of DMXTD and DEp values provides more detailed information to assess water needs in mature olive orchards than the use of Q or TDV records alone. © 2011 Elsevier B.V.

Villaverde J.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Posada-Baquero R.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Rubio-Bellido M.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Morillo E.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC
Journal of Soils and Sediments | Year: 2013

Purpose: The herbicide diuron has the unfortunate property of being strongly adsorbed onto soil organic matter particles, and hence, is slowly degraded in the environment because of its reduced bioavailability. The aim of this work was to gain insight into the fate and behaviour of diuron in the soil-water system, and develop and test an environmentally friendly soil decontamination technique that could give rise to an enhancement of diuron mineralisation by sensitive soil endogenous microorganisms, by means of increasing the bioavailability of the pollutant employing cyclodextrin (CD) solutions what would represent an improvement from both economic and environmental standpoints. Materials and methods: Selected soil colloidal components: montmorillonite, a synthetic humic acid and a synthetic acicular goethite, and two different soils were employed in this study to perform batch adsorption-desorption experiments. Desorption experiments were performed using a 0.01 M Ca(NO3)2 solution with and without hydroxypropyl-β-cyclodextrin (HPBCD) 50 mM. Assays to study the mineralisation of 14C-labelled diuron were performed in respirometers, into which 10 g of soil and 50 mL of mineral salts medium (MMK) were placed, obtaining a final concentration of 50 mg kg-1 and a radioactivity of approximately 900 Bq per flask. Results and discussion: Humic acid could be clearly discerned as the major colloidal component responsible for adsorption. HPBCD was used in diuron desorption experiments from soil, showing a strong extracting power on its removal. The mineralisation of diuron in the presence and absence of HPBCD was tested in a soil managed with diuron for several years, involving therefore the presence of microorganisms that have some specificity for diuron. Natural soil attenuation for diuron was improved when a HPBCD solution was used in the presence of micronutrients as a bioavailability enhancer, obtaining 66 % of mineralisation in comparison to that obtained with only micronutrients addition (44 %). Conclusions: The use of HPBCD solution at a very low concentration of only 10 times the diuron equimolar concentration in soil, acts as a bioavailability enhancer, accelerating the passage of the diuron-desorbing fraction from the soil particle surface to the soil solution, and hence, improving the accessibility of the microorganisms to the herbicide. Diuron mineralisation rate and the extent of its mineralisation were improved when the HPBCD solution was employed in the presence of micronutrients. © 2013 Springer-Verlag Berlin Heidelberg.

Fernandez J.E.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC | Cuevas M.V.,Institute Recursos Naturales y Agrobiologia IRNAS CSIC
Agricultural and Forest Meteorology | Year: 2010

Precise irrigation is essential in arid and semi-arid areas where water is scarce. This has impelled the scientific community to develop new technologies for scheduling irrigation. Of these, the ones relying on plant-based water-stress indicators have been found to have the greatest potential. Thus, measurements of stem water content, canopy temperature, sap flow, and stem diameter variation (SDV), among other variables, have proved useful not only for research purposes, but also for precise irrigation scheduling in commercial orchards. In this work we focus on the use of SDV records for irrigation scheduling. Of those mentioned above, this is the water-stress indicator that has received most attention from the scientific community, in terms of its potential for irrigating commercial orchards. Apart from being capable of an early detection of water stress, even if this is mild, SDV can be continuously and automatically recorded. This is a clear advantage over conventional indicators such as stem water potential (Ψstem). Among the SDV-derived indices that are useful for scheduling irrigation, the maximum daily shrinkage (MDS) and stem growth rate (SGR) are the most widely used. For young trees, and in periods of rapid stem growth, SGR could be a better indicator than MDS. In periods of negligible growth, however, SGR cannot be used as an indicator of plant water stress. Considerable differences in both MDS and SGR as a function of crop load have been reported for some species. It has been found, that SDV outputs are affected by seasonal growth patterns, crop load, plant age and size, and other factors, apart from water stress. Thus, expert interpretation of SDV records is required before using them for scheduling irrigation, which limits their potential for automating the calculation of the irrigation dose. For some species, the MDS vs Ψstem relationships show diurnal hysteresis and seasonal changes. Some relationships also shown an increase of MDS as the plant water potential fell to a certain value, after which MDS decreases as the plant water potential became more negative. This has been reported for peach, lemon, grapevine and olive, among other species. Although SDV-derived indices show a high plant-to-plant variability, in most cases the signal intensity is high enough to achieve an acceptable sensitivity, which, for peach, lemon and pepper has been found to greater than that of Ψstem and leaf conductance (gl). In plum, apple and grapevine, however, Ψstem is more sensitive than MDS and SGR. In any case, the usefulness of an SDV-derived index for irrigation scheduling must be evaluated for the orchard conditions. In this work we describe the qualities that must be considered in such evaluation. One of them, the signal intensity, is being successfully used to schedule low-frequency irrigation in orchards of a variety of species, for both full- and deficit-irrigation treatments. When combined with aerial or satellite imaging, SDV measurements are useful for scheduling irrigation in large orchards with high crop-water-stress variability. © 2009 Elsevier B.V. All rights reserved.

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