Changes in growth rate, root morphology and water use efficiency of potted Callistemon citrinus plants in response to different levels of water deficit

Callistemon is widely used as a flowering shrub in gardening and landscaping in the Mediterranean area. However, prolonged or severe water stress may alter its physiological and morphological behaviour. Callistemon citrinus plants were grown in nursery conditions and subjected to three irrigation treatments: a control (watered to container capacity) and two water deficit treatments of 50 and 25% of the amount of water supplied in the control treatment (moderate and severe deficit irrigation, respectively). After 53 weeks, the moderate deficit irrigation plants showed a lower relative growth rate but increased root/shoot ratio, improved the root system and increased water use efficiency, while flowering and leaf colour were unaffected. However, severe deficit irrigation reduced flowering and affected leaf colour. Both deficit irrigation treatments reduced stomatal conductance, suggesting an efficient and adaptive stomatal control in this species. These reductions were marked after longer periods in plants submitted to severe deficit irrigation, which decreased photosynthesis and could delay plant recovery and cause permanent damage. Differences between stem and leaf water potential values have seen to be a good indicator of instantaneous shoot transpiration. Water consumption was influenced by the active periods of growth and inflorescence formation. It is concluded that moderate deficit irrigation can be used successfully in C. citrinus plant production to reduce water consumption while maintaining good overall quality. © 2013 Elsevier B.V.This work was supported by the Spanish Ministry of Science and Innovation (AGL 2008-05258-C02-1-2, AGL 2011-30022-C02-01) and Fundación Séneca (15356/PI/10).Peer Reviewe

Long-term effect of salinity on plant quality, water relations, photosynthetic parameters and ion distribution in Callistemon citrinus

The effect of saline stress on physiological and morphological parameters in Callistemon citrinus plants was studied to evaluate their adaptability to irrigation with saline water. C. citrinus plants, grown under greenhouse conditions, were subjected to two irrigation treatments lasting 56 weeks: control (0.8 dS·m-1) and saline (4 dS·m-1). The use of saline water in C. citrinus plants decreased aerial growth, increased the root/shoot ratio and improved the root system (increased root diameter and root density), but flowering and leaf colour were not affected. Salinity caused a decrease in stomatal conductance and evapotranspiration, which may prevent toxic levels being reached in the shoot. Net photosynthesis was reduced in plants subjected to salinity, although this response was evident much later than the decrease in stomatal conductance. Stem water potential was a good indicator of salt stress in C. citrinus. The relative salt tolerance of Callistemon was related to storage of higher levels of Na+ and Cl- in the roots compared with the leaves, especially in the case of Na+, which could have helped to maintain the quality of plants. The results show that saline water (around 4 dS·m-1) could be used for growing C. citrinus commercially. However, the cumulative effect of irrigating with saline water for 11 months was a decrease in photosynthesis and intrinsic water use efficiency, meaning that the interaction of the salinity level and the time of exposure to the salt stress should be considered important in this species. © 2014 German Botanical Society and Royal Botanical Society of the Netherlands.This work was supported by the Spanish Ministry of Science and Innovation (AGL 2011-30022-C02-01-02) and Fundación Séneca (15356/PI/10).Peer Reviewe

Comparison of individual and combined effects of salinity and deficit irrigation on physiological, nutritional and ornamental aspects of tolerance in Callistemon laevis plants

The effect of water deficit, salinity and both applied simultaneously on several physiological and morphological parameters in the ornamental plant Callistemon laevis was studied to identify the tolerance mechanisms developed by this species to these sources of stress and to evaluate their adaptability to such conditions. C. laevis plants were grown in pots outdoors and subjected to four irrigation treatments lasting ten months: control (0.8dSm-1, 100% water holding capacity), water deficit (0.8dSm-1, 50% of the amount of water supplied in control), saline (4.0dSm-1, same amount of water supplied as control) and saline water deficit (4.0dSm-1, 50% of the water supplied in the control). Water and saline stress, when applied individually, led to a reduction of 12% and 39% of total biomass, respectively, while overall plant quality (leaf color and flowering) was unaffected. However, saline water deficit affected leaf color and flowering and induced an excessive decrease of growth (68%) due to leaf tissue dehydration and a high leaf Cl and Na concentration. Biomass partitioning depended not only on the amount of water applied, but also on the electrical conductivity of the water. Water stress induced active osmotic adjustment and decreased leaf tissue elasticity. Although both Na and Cl concentrations in the plant tissues increased with salinity, Cl entry through the roots was more restricted. In plants submitted to salinity individually, Na tended to remain in the roots and stems, and little reached the leaves. However, plants simultaneously submitted to water and saline stress were not able to retain this ion in the woody parts. The decrease in stomatal conductance and photosynthesis was more marked in the plants submitted to both stresses, the effect of which decreased photosynthesis, and this together with membrane damage delayed plant recovery. The results show that the combination of deficit irrigation and salinity in C. laevis is not recommended since it magnifies the adverse effects of either when applied individually. © 2015 Elsevier GmbH.This work was supported by the Spanish Ministry of Economy and Competitiveness (project CICYT AGL 2011-30022-C02-01-02) and Fundación Séneca-Agencia de Ciencia y Tecnología de la Región de Murcia (15356/PI/10).Peer Reviewe

On split Leibniz algebras

Con intención de acometer la estructura de álgebras de Leibniz arbitrarias (sin restricciones ni en su dimensión ni en su cuerpo base), definimos las álgebras de Leibniz split como la generalización natural de las álgebras de Lie split. Desarrollando técnicas de conexiones de raíces para estas álgebras, mostramso que son suma de una subespacio de una subálgebra abeliana e ideales bien definidos, tales que estos ideales tienen producto nulo cuando se multiplican dos distintos. En caso de que una álgebra de Leibniz split sea de longitud máxima caracterizamos su simplicidad en términos de conexiones de raíces

On the structure of graded Lie superalgebras

Estudiamos la estructura de supéralgebras de Lie graduadas (por un grupo G) con dimensión arbitraria y sobre un cuerpo base arbitrario. Mostramos que cualquier álgebra de este tipo es suma de un subespacio de su componente homogénea asociada al elemento neutro del grupo G con el resto de componentes homogéneas de la graduación, siendo todas ideales de la superálgebra cumpliendo que el producto de dos distintos es nulo. Bajo ciertas condiciones, mostramos que toda superálgebra de Lie graduada es suma directa de componentes simples, las cuales resultan ser ideales graduados gr-simples (simples para la graduación dada por G) de dimensión baja, cumpliendo nuevamente que el producto de dos distintos es siempre cero

Creation of a virtual museum as a learning tool in the teaching of the Manufacturing Engineering subject

Teaching subjects such as Manufacturing Engineering requires the use of effective teaching tools, which help students in their learning process. While the traditional transmission model can be effective when teaching concepts and theoretical contents, others activities are essential to allow students to participate, act or reflect, thus developing skills and competences, such us communication, teamwork, and creativity. This paper presents a learning tool based on the creation of a virtual museum related to the Manufacturing Engineering field, which is included as a coursework in the teaching program of the subject "Manufacturing Engineering". This subject is taught at the second year of different degrees at the Industrial Engineering School of the University of Malaga and a percentage of its final grade comes from this activity. The museum is materialized through the posters whose format is similar to those presented at conferences and whose content may be referred to three topics (object, process or biography). Once the students are given the necessary instructions, each project is selected by a work group and its development is supervised in the next two sessions by the lecturer. In the final stage, each group give the presentation about their work. The analysis of the students’ grades obtained from both this activity and the whole subject makes it possible to quantify the impact of this type of activities on the student learning and achievement. Eventually, best posters will be part of the department collection, being accessible to students in subsequent years.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Regulated deficit irrigation in different phenological stages of potted geranium plants: Water consumption, water relations and ornamental quality

The irrigation water requirements and sensitivity to water deficits of ornamental plants is of great interest to horticultural producers for planning irrigation strategies. The effect of different deficit irrigation strategies on physiological and morphological parameters in geranium plants was studied in different growth phases to evaluate how such strategies can be safely used and to ascertain whether the flowering phase is sensitive to deficit irrigation. Pelargonium × hortorum L. H. Bailey plants, grown in a controlled growth chamber, were subjected to four irrigation treatments: control (100 % water field capacity throughout the experiment), sustainable deficit irrigation (75 % water field capacity throughout the experiment), and two regulated deficit irrigation treatments that included water stress during the vegetative growth phase or during the flowering development phase. Although the total amount of irrigation water was similar in the three deficit irrigation treatments (around 80 % of the control value), the lowest values for both height and flowering were found when deficit irrigation was applied during flowering. This indicates that plant quality does not only depend on the amount of water applied but also on the time when the reduction is applied, and that flowering is the most sensitive phase to water stress. Evapotranspiration was related to the formation of inflorescences and to increased plant height. When the irrigation strategy was changed, plants increased or decreased their water consumption and stomatal conductance to adjust to the new conditions by regulating stomatal opening, although, in general, the values of both parameters remained below those observed in the control plants. © 2012 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.This work was supported by the Spanish Ministry of Science and Innovation (AGL 2008-05258-C02-1-2, AGL 2011-30022-C02-01) and Fundación Séneca (15356/PI/10).Peer Reviewe

Evidence about asymmetric price transmission in the main European fuel markets: from TAR-ECM to Markov-switching approach

This paper presents new evidence on the existence of asymmetries in the transmission of shocks in oil prices in the main European fuel markets and their relation to the so-called rockets and feathers effect. Our approach differs from the existing literature in two ways: (1) the data used: we use forward prices rather than spot prices because fuel leaders use forward contracts to buy crude oil. (2) The methodological approach is different. We adopt a more sophisticated econometric model, the Markov-switching model, and use it to contrast the robustness of the results obtained with the TAR-ECM methodology with an endogenous threshold (nonzero threshold). In general, the results show evidence of an asymmetric response of gasoline and diesel prices to changes in the price of crude oil, both in the short-run and with respect to the adjustment towards long-run equilibrium. These price asymmetries fall in line with the “rockets and feathers” hypothesis.Ministerio de Economía y Competitividad | Ref. ECO2015-67305-PBanco de España | Ref. PR71/15-20229Ministerio de Economía y Competitividad | Ref. ECO2015-68367-RXunta de Galicia | Ref. GRC2014/02

Impact of Spent Mushroom Substrates on the Fate of Pesticides in Soil, and Their Use for Preventing and/or Controlling Soil and Water Contamination: A Review

Intensive crop production involves a high consumption of pesticides. This is a cause of major environmental concern because the presence of pesticides in water is becoming increasingly common. Physicochemical methods based on soil modification with organic residues have been developed to enhance the immobilization and/or degradation of pesticides in agricultural soils, which may control both the diffuse and the point pollution of soils and waters. This review summarizes the influence of spent mushroom substrate (SMS) on the environmental fate of pesticides when both are simultaneously applied in agriculture. The processes of adsorption, leaching and dissipation of these compounds in SMS-amended soils were evaluated at laboratory and field scale. Relationships were established between the experimental parameters obtained and the properties of the soils, the SMS, and the pesticides in order to determine the effect that the application of SMS in agricultural soils has on the environmental impact of pesticides. Accordingly, this review highlights the use of SMS as a strategy for the prevention and/or control of soil and water contamination by pesticides to strike a balance between agricultural development and the use of these compounds.The authors are grateful to the Spanish Ministry of Science and Innovation (Projects AGL2007-61674/AGR and AGL2010-15976/AGR), and Regional Junta de Castilla y León (Project CSI03A09). J.M.M.-B. thanks Ministry of Economy and Competitiveness for his “Juan de la Cierva-Incorporación” postdoctoral contract (IJCI-2014-19538). We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

"Alternanthera sessilis" (L.) R. Br. ex DC. (Amaranthaceae) en la Península Ibérica

Alternanthera sessilis (L.) R. Br. ex DC. (Amaranthaceae) in the Iberian PeninsulaPalabras clave. Alternanthera sessilis, Amaranthaceae, alóctona, Península Ibérica.Key Words. Alternanthera sessilis, Amaranthaceae, alien plant, Iberian Peninsula