Stomatal control of water use in olive tree leaves

Little is known about the strategies used by olive trees to overcome the long dry periods typical of the areas where they are cropped. This makes it difficult to optimize the water supply in orchards. To study the control of water consumption by olive trees, measurements of leaf water potential (Ψ) and stomatal conductance to H2O (g) were made on 26-year-old Manzanillo olive trees under three irrigation treatments. The first treatment provided enough water to cover the crop water demand, the next treatment supplied one third of that rate, and the final treatment was no irrigation at all, typical of dry-farming conditions. Under conditions of high vapour pressure deficit of the air (D(a)), the olive trees prevented excessive water loss by closing their stomata. Leaves of the current year showed better stomatal control than did the 1-year-old leaves. The upper-bound functional relationships between g and D(a) and photon flux density (I(P)) were obtained by boundary-line analysis, based on a technique of non-linear least squares. Maximum values of g were observed at relatively low levels of I(p), from about 500 μmol m-2 s-1, and a proportional decrease in g with increasing D(a) was also found, at least for values of up to approximately 3.5 kPa. Higher values of g were observed in the morning than in the afternoon, for similar levels of I(P) and D(a). Unirrigated olive trees recovered quickly after the dry season, showing values of Ψ and g similar to those of irrigated trees after just two days.Peer Reviewe

Activities of the European topic centre on soils: the Spanish information system on soils

3 pages, 9 references.-- Forma parte del capítulo Data Availability.-- Trabajo presentado al International Workshop celebrado del 9-11 de octubre 1999, en Alghero, Italia.Within the general activities of the ETC on soils one of the tasks is the development of the Spanish Information System on Soils. This activity is being developed under the agreement between the Spanish Ministry of Environment (MIMAM) and the Spanish High Council for Research (CSIC). This presentation focuses on the development of a database on soil hydraulic properties within the framework of the mentioned agreement MIMAM-CSIC. The database try to compile all existing data of hydraulic properties of the spanish soils. For the development of such a database we have taken into account the existing database of hydraulic properties of european soils (HYPRES) in which the IRNAS (CSIC) of Seville was a contributor. The spanish database on soil hydraulic properties includes detailed references of other soil properties, and the temporal variability of hydraulic properties due to the different soil use and management. This database can be an useful tool in the study of desertification processes, erosion and transport of contaminant.Peer reviewe

Uso de compost que incluyen cenizas de biomasa para el cultivo de sandía

5 páginas.-- 4 tablas.-- 10 referenciasLa biomasa representa entre el 8 y el 15% del suministro energético mundial como electricidad, calor y combustibles para transporte, y podría contribuir hasta un 33-50% del consumo de energía primaria en 2050. Buena parte de esta energía se obtiene por combustión directa de biomasa generando 476 millones de toneladas de cenizas. Por el contrario de las cenizas derivadas del carbón, las cenizas de biomasa están libres de elementos contaminantes y en el caso de las de biomasa derivada de productos agrícolas y agroindustriales suelen presentar concentraciones apreciables de elementos fertilizantes como K, Mg, además de Ca por lo que su ciclo puede completarse si son reutilizadas en agricultura en lugar de depositadas en vertedero. En el presente trabajo se estudia el uso de un compost mixto de residuos agroindustriales y cenizas de orujo de aceituna como enmienda en un cultivo de sandía (Citrullus lanatus variedad Augusta). Como comparación se usaron tratamientos con el mismo compost de residuos agroindustriales o con fertilización mineral sólo (Control, 220 kg K2O ha-1 como KCl). El compost con cenizas se aplicó a una dosis de 10.000 kg ha-1 y el compost sin cenizas a la dosis de 20.000 kg ha-1. Cada tratamiento se efectuó por cuadruplicado, cultivando la sandía al aire libre. Se determinaron las propiedades del suelo y el rendimiento y estado nutricional del cultivo. Los resultados indican que la inclusión de este tipo de cenizas en las enmiendas de cultivos exigentes nutrientes como potasio puede ser ventajosa, ya que se mantiene la producción del tratamiento control (alrededor de 100000 kg ha-1) pero con mayor tamaño del fruto (más 1,3 kg/fruto en el tratamiento con cenizas).Este trabajo se ha realizado en el marco del proyecto CTQ2013-46804-C2-1-R financiado por el Ministerio de Economía y Competitividad y ha sido parcialmente financiado por el programa FEDER de la Junta de Andalucía. Los autores agradecen a la empresa Fertiormont por la cesión de los productos.Peer reviewe

Umbrales sostenibles de estrés hídrico durante el endurecimiento del hueso en la producción de aceituna de mesa

La programación del riego deficitario controlado (RDC) es una necesidad derivada de la escasez de agua disponible para el riego. La resistencia al estrés hídrico de los diferentes estados fenológicos en olivar está bastante bien documentada pero no así los niveles de estrés hídrico. El objetivo de este trabajo es sugerir en base a experimentos realizados en los últimos 7 años los niveles de estrés hídrico para el manejo del RDC en olivar.Los experimentos descritos en la presente comunicación se han desarrollado en la finca “La Hampa” propiedad del IRNAS (CSIC) en Coria del Río (Sevilla), en un olivar de 37 años cv “Manzanillo” y a un marco de 7*5m. Los experimentos se establecieron con diferentes tratamientos de riego, aplicando condiciones de estrés hídrico durante endurecimiento de hueso y unas semanas antes de cosecha. Se discute los diferentes umbrales detectados y su efecto en cosecha, cantidad y calidad, y en la fisiología de la planta en el años en curso en el ciclo bianual del olivo.Ministerio de Economía y Competitividad AGL2007-66279-C03-00Ministerio de Economía y Competitividad AGL2010-19201-CO4-03Ministerio de Economía y Competitividad AGL2013-45922-C2-1-

Water Relations in the Irrigation Scheduling of Olive Orchards

Olive trees (Olea europea L) are traditional Mediterranean specie. The agricultural management of olive orchards has been changed from 90’s of the last century. The most important change is the great increase of the irrigation surface. This new water demand has been produced in water scarcity areas. Such conditions and the traditional rainfed management of the orchards have produced very restrictive water used. The traditional irrigation scheduling based on water budget is a useful tool in conditions of full irrigation, but most of the olive orchards are deficit irrigated. In the last decades, plant water status measurements have been suggested in different fruits trees in order to improve the management of deficit irrigation. In this work, results of several experiments in different olive orchards using midday stem water potential and trunk daily diameter are presented. The water stress sensitivity and the real commercial utility are discusse

Limitations and usefulness of maximum daily shrinkage (MDS) and trunk growth rate (TGR) indicators in the irrigation scheduling of table olive trees

8 páginas.-- 7 figuras.-- 2 tablas.-- 32 referenciasMaximum daily trunk shrinkage (MDS) is the most popular indicator derived from trunk diameter fluctuations in most fruit trees and has been reported to be one of the earliest signs in the detection of water stress. However, in some species such as olive trees (. Olea europaea L.), MDS does not usually change in water stress conditions and trunk growth rate (TGR) has been suggested as better indicator. Most of this lack of sensitivity to drought conditions has been related to the relationship between the MDS and the water potential. This curvilinear relationship produces an uncertain zone were great variations of water potential do not imply any changes of MDS. The MDS signal, the ratio between measured MDS and estimated MDS with full irrigation, has been thought to be a better indicator than MDS, as it reduces the effect of the environment. On the other hand, though literature results suggest an effect of environment in TGR values, there are not clear relationship between this indicator and meteorological data. The aims of this work are, on one hand, to study the improvements of the baseline approach in the MDS signal and, on the other, study the influence of several meteorological variables in TGR. Three years' data from an irrigation experiment were used in to carry out the MDS analysis and six years' data for full irrigated trees during pit hardening period were used for TGR study. The comparison between MDS vs. water potential and MDS signal vs. water potential presented a great scattering in both relationships. Values of MDS signal between 1.1 and 1.4 were always identified with moderate water stress conditions (-1.4 to -2. MPa of water potential). However, since this MDS signal values are around the maximum in the curvilineal relationship with water potential, greater values of MDS signal (in the range of 1.1-1.4) were not necessary lower values of water potential. In addition, during low fruit load seasons MDS signal was not an accurate indicator. On the other hand, absolute values of several climatological measurements were not significantly related with TGR. Only daily increments explain part of the variations of TGR in full irrigated trees. In all the data analysed, the daily increment of average vapour pressure deficit was the best indicator related with TGR. The increase of this indicator decreased TGR values. In addition, the agreement between this indicator and TGR was affected for fruit load. Great yield seasons decrease the influence of VPD increment in TGR.This research was supported by the Spanish Ministerio de Ciencia e Innovación (MICINN), (AGL2010-19201-CO4-03). Thanks are due to J. Rodriguez and A. Montero for help with field measurements.Peer reviewe

Regulated deficit irrigation in table olive trees during a sensitive period

Olive tree is one of the most important irrigated fruit at Spain (around 400.000 ha). The water needs in olive orchard are greater than the water availability. Therefore, deficit conditions are common at the field. The aim of this work is to study a regulated deficit irrigation (RDI) scheduling based on midday stem water potential (Y) that limits irrigation before harvest. The experiment was performed at La Hampa experimental farm (Coria del río, Seville, Spain) in 45 years-old olive (cv Manzanillo). Three irrigation treatments in a complete randomized block design were performed during 2014.This research was supported by the Spanish Ministerio de Economía y Competitividad (MINECO), (AGL2013-45922-C2-1-R).Peer Reviewe

Heat-pulse measurements of sap flow in olives for automating irrigation: tests, root flow and diagnostics of water stress

26 páginas, 10 figuras, 1 tabla, 32 referencias.-- [email protected] compensation heat-pulse method for measuring sap flow is tested here in olive trees (Olea europaea L.). We describe a rigorous three-way examination of the robustness of the technique for this species, and examine the potential of the technique for an automatic control of the irrigation system. Two tests were carried out using heat-pulse gear inserted into the stem of 12-year-old ‘Manzanilla’ olive trees. One test used forced-flow through a stem section, and the other involved measured water uptake by an excised tree. The measured sap flow in these two tests was in agreement with calculations from heat-pulse velocities when using a standard ‘wound correction’ to account for the presence of the probes and the disruption to the sap flow. Thus, this technique for monitoring transpiration can, we feel, be used with confidence in olives. The third experiment was carried out in the field, where we analysed sap flow data from two 29- year-old olive trees—one tree was under regular drip irrigation and the other was from dry-farming conditions. We use measurements of sap flow in the trunk to examine the hydraulic functioning of the tree, and to explore some diagnostics of water stress. Our heat-pulse measurements in the irrigated olive tree exhibited a profile of sap flow that was weighted towards the outer xylem of the tree trunk while the water-stressed trees in the field showed a profile of sap flow weighted towards the centre of the trunk. The loss of hydraulic functioning in the outermost section of the vascular system, as a result of water stress, we consider to be due both to stomatal control and to embolisms in the xylem vessels. The fourth experiment was also carried out in the field, in which sap flow measurements were made at three locations in the trunk as well as in two roots of another 29-year-old olive tree. The soil explored by each root, on opposite sides of the trunk, was differentially wetted by separate irrigation of each side. Our data showed that the surface roots were able to absorb water immediately after wetting, despite a reasonably prolonged period of moderate drought. Root activity quickly shifted to the regions where the soil had been wetted. A root in dry soil exhibited no flow at night, whereas sap flows of about 0.02 l h 1 were measured around midnight in the root drawing water from the wetter soil. Our observations suggest that the hydraulic behaviour of the trunk and surface roots might be used as a diagnostic of the onset, or severity, of water stress. Here there is not the imperative to replicate, for the prime goal is not transpiration estimation. Rather interpretation of the diurnal dynamics is used to infer the onset, or severity of water stress. The compensation heat-pulse seems a suitable technique for automatically controlling the irrigation system of olives, and probably other trees, based either on the estimation of the short-time dynamics of transpiration, or on changes in the hydraulic behaviour of the trees.The Comisión Interministerial de Ciencia y Tecnología of the Spanish Ministry of Education and Science financial support this project.Peer reviewe

Heat-pulse measurements of sap flow in olives for automating irrigation: tests, root flow and diagnostics of water stress

26 páginas, 10 figuras, 1 tabla, 32 referencias.-- [email protected] compensation heat-pulse method for measuring sap flow is tested here in olive trees (Olea europaea L.). We describe a rigorous three-way examination of the robustness of the technique for this species, and examine the potential of the technique for an automatic control of the irrigation system. Two tests were carried out using heat-pulse gear inserted into the stem of 12-year-old ‘Manzanilla’ olive trees. One test used forced-flow through a stem section, and the other involved measured water uptake by an excised tree. The measured sap flow in these two tests was in agreement with calculations from heat-pulse velocities when using a standard ‘wound correction’ to account for the presence of the probes and the disruption to the sap flow. Thus, this technique for monitoring transpiration can, we feel, be used with confidence in olives. The third experiment was carried out in the field, where we analysed sap flow data from two 29- year-old olive trees—one tree was under regular drip irrigation and the other was from dry-farming conditions. We use measurements of sap flow in the trunk to examine the hydraulic functioning of the tree, and to explore some diagnostics of water stress. Our heat-pulse measurements in the irrigated olive tree exhibited a profile of sap flow that was weighted towards the outer xylem of the tree trunk while the water-stressed trees in the field showed a profile of sap flow weighted towards the centre of the trunk. The loss of hydraulic functioning in the outermost section of the vascular system, as a result of water stress, we consider to be due both to stomatal control and to embolisms in the xylem vessels. The fourth experiment was also carried out in the field, in which sap flow measurements were made at three locations in the trunk as well as in two roots of another 29-year-old olive tree. The soil explored by each root, on opposite sides of the trunk, was differentially wetted by separate irrigation of each side. Our data showed that the surface roots were able to absorb water immediately after wetting, despite a reasonably prolonged period of moderate drought. Root activity quickly shifted to the regions where the soil had been wetted. A root in dry soil exhibited no flow at night, whereas sap flows of about 0.02 l h 1 were measured around midnight in the root drawing water from the wetter soil. Our observations suggest that the hydraulic behaviour of the trunk and surface roots might be used as a diagnostic of the onset, or severity, of water stress. Here there is not the imperative to replicate, for the prime goal is not transpiration estimation. Rather interpretation of the diurnal dynamics is used to infer the onset, or severity of water stress. The compensation heat-pulse seems a suitable technique for automatically controlling the irrigation system of olives, and probably other trees, based either on the estimation of the short-time dynamics of transpiration, or on changes in the hydraulic behaviour of the trees.The Comisión Interministerial de Ciencia y Tecnología of the Spanish Ministry of Education and Science financial support this project.Peer reviewe

A more sustainable and efficient definition of Regulated Deficit Irrigation phases in olive (Olea europaea L.)

Resumen del trabajo presentado en 20th EGU General Assembly, clelebrada en Viena (Austria) del 04 al 13 de abril de 2018.Water is a limited but highly essential resource, with large quantities required for agriculture. Regulated Deficit Irrigation (RDI) is an agricultural technique with great relevance for water savings worldwide, in which water stress is imposed by irrigation withholding based on fruit growth phases. The objective of this method is to identify phases where water stress has little or no effect on yield. RDI in olive has been demonstrated as an efficient tool to save water without negatively affecting yield. In olive trees, the mid-summer “pit hardening” is recognized as the most drought-resistant phenological stage, and has been used successfully for RDI water savings even though neither the description, boundaries, nor length of the period have been cleared reported. Many studies merely utilize a constant reference date for pit hardening, providing no explanation regarding how it was estimated or measured, while a few cases report the resistant to a knife-cut as the proper method to identify hardening, but leave unclear whether it represents its onset or completion. Recent studies have addressed these uncertainties, better showing the nature and duration of olive pit hardening, to which RDI can now be fitted. The objective of this current work was to determine if a RDI strategy more precisely fitted to pit hardening influences yield. In Ciudad Real (Spain) in 2016 and 2017, four irrigation treatments were applied in an ‘Arbequina’ olive orchard planted at 7 x 4.75 m in 1999. Treatment T1 consisted in water stress during pit hardening, aiming to maintain stem water potential (SWP) of -2 MPa during this phase. Treatment T2 was severely water stressed, aimed at maintaining -3 MPa during the same phase. In the rest of the season, before and after pit hardening, both treatments were irrigated to prevent water stress. Additionally, a highly deficit treatment was established (T3), irrigated only after pit hardening was completed. A control treatment (T0), irrigated following FAO methodology, was established to determine potential yield. Irrigation water savings with respect to T0 were approximately 45%, 57%, and 77% for T1, T2, and T3, respectively. There were no significant yield differences among treatments, although 2017 was nearly significant (P = 0.06), as when both years were considered together, due to the low yield of T3. Average yields from the two years were 25, 24, 23 and 21 kg tree-1 in T0, T1, T2 and T3, respectively. In conclusion, basing RDI on a new, more precise definition of the pit hardening phase produces similar yields with higher water savings, with the consequent environmental, economic and energetic benefits.Peer reviewe