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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. Source

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. Source

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. Source

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. Source

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. Source

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