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For years, one of the major concerns of agronomists has been the study of how variations in the crop environment can affect proper crop development. A variety of factors must be considered, including factors such as plant genetics, climatic conditions or soil, and factors directly dependent on man such as technology or labour. In the search for sustainable development, all these factors must coexist in perfect harmony in order AbstractThe determination of leaf water potential is useful in the establishment of irrigation guidelines for agricultural crop management practices and requires the use of various methods, among which thermocouple psychrometers (TCP). TCP have been widely used for this purpose. However, the psychrometric technique is complex and difficult to understand and the instrumentation required is difficult to handle. For this reason, a profound knowledge of the different aspects involved in the technique -which have not been clearly explained in the literature-is required. This paper reviews a number of research areas of TCP and focuses on three very specific fields: a) main applications of phsychrometry in field studies; b) determination of the measurement accuracy of psychrometric equipment, accuracy per se and accuracy tested against alternative methods; c) main errors and handling difficulties of TCP in the field. Research in these areas provides an updated overview of TCP as a method for determining water relations in plant material that will contribute criteria to select the most suitable technique according to the type of plant material and the purpose of the research and will highlight the types of instruments, accuracies and errors that have detrimental effects on measurements.Additional key words: hygrometric technique; irrigation; isopiestic technique; pressure chamber; psychrometric technique. ResumenRevisión. Aplicación de la psicrometría en campo a material vegetal: precisión y dificultades de manejo La determinación del potencial hídrico foliar es muy útil en el establecimiento de directrices de riego en las prácti-cas de manejo agrícola de los cultivos, requiriéndose del uso de diferentes métodos como los psicrómetros termopar (TCP). Los TCP han sido ampliamente utilizados. Sin embargo, se trata de una técnica compleja de difícil manejo. Por lo tanto, se requiere un profundo conocimiento de los diferentes aspectos involucrados en la técnica, que no han sido claramente explicados en los diferentes estudios publicados. Este artículo revisa una serie de líneas de investigación de los TCP. Estas áreas de investigación se han centrado en tres campos muy específicos: a) principales actuaciones en campo empleando la psicrometría; b) especificación de la precisión de los equipos, per se y frente a otras metodologías alternativas; c) principales errores y dificultades de manejo en campo de los psicrómetros. La investigación en esta área permitirá aportar una visión actualizada sobre los TCP como método de determinación de relaciones hídricas en material vegetal, aportando criterios de sele...

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The Water Framework Directive (WFD) aims to solve the problems derived from the use of water, a limited natural resource, by extending the scope of protection to all water uses. The WDF defines the ecological status of water bodies by characterizing each water body type and establishing conditions for the quality elements. This paper identifies valid indicators for defining the ecological status of Estanco River Basin, located in the province of Lugo, NW of Spain, by using the methodology proposed in the WFD. In addition, this study highlights the obstacles for a correct application of the WFD in the study river basin. After characterization of the study river basin and establishment of specific reference conditions, this study presents conclusions about the usefulness of the WFD in the development of specific programmes for improving the ecological status of rivers.

The new scenario of water policy favoured by the European Union Directive establishing a framework for Community action in the field of water policy, and by the National Irrigation Plan in Spain, requires sustainable and integrated management of water resources. A total of 119 farmers were surveyed in order to implement a management model in the Lemos Valley District, where irrigation plays a main role. The survey provides a sample of representative farms, from which real-time updated information can be obtained. This information can be used as the basis for decision-making during the process of implementation and development of the management model. In the study area, farms are small and show a high fragmentation level. Moreover, the farmers who in charge of them are old. The state of distribution network forces farmers to abandon irrigation because they lack motivation to irrigate. Therefore, irrigation rehabilitation must be accompanied by socio-economic profile and by technical measures that allow rehabilitation to be undertaken.