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Izquierdo J.,Polytechnic University of Catalonia | Bastida F.,University of Huelva | Lezaun J.M.,Instituto Tecnico Y Of Gestion Agricola Itga | Sanchez del Arco M.J.,Instituto Madrileno Of Investigacion Y Desarrollo Rural | Gonzalez-Andujar J.L.,CSIC - Institute for Sustainable Agriculture
Weed Research

Lolium rigidum is an extremely competitive and prevalent grass weed in cereal fields of Mediterranean areas. The proper timing of control measures is a prerequisite to maximising herbicide efficacy, in terms of both improved control and reduced herbicide inputs. The development of models to predict emergence flushes will contribute to this goal. Pooled cumulative emergence data obtained during three seasons from a cereal field were used to develop a Gompertz model. This explained relative seedling emergence from crop sowing onwards as a function of: (i) standard soil thermal time accumulation (TT) with a base temperature of 1.8°C and (ii) soil thermal time accumulation corrected for soil moisture (cTT). For the latter, no thermal time accumulation was computed for days in which the soil water balance within the upper 10-cm soil layer indicated no water available for plants, because evapotranspiration was greater than rainfall plus the stored water remaining from the previous day. The model was validated with six datasets from four different sites and seasons. Compared with TT, the model based on cTT showed better performance in predicting L. rigidum emergence, particularly in predicting the end of emergence. Complemented with in-field observations to minimise deviations, the model may be used as a predictive tool to better control this weed in dryland cereal fields of Mediterranean climate areas. © 2013 European Weed Research Society. Source

Gonzalez-Fernandez I.,CIEMAT | Bermejo V.,CIEMAT | Elvira S.,CIEMAT | de la Torre D.,Complutense University of Madrid | And 11 more authors.
Atmospheric Environment

Correct estimation of leaf-level stomatal conductance (gsto) is central for current ozone (O3) risk assessment of wheat yield loss based on the absorbed O3 phytotoxic dose (POD). The gsto model parameterizations developed in Europe must be checked in the different climatic regions where they are going to be applied in order to reduce the uncertainties associated with the POD approach.This work proposes a new gsto model parameterization for estimating POD of Triticum aestivum and Triticum durum under Mediterranean conditions, based on phenological observations over 25 years and gsto field measurements during 5 growing seasons. Results show that POD in the Mediterranean area might be higher than previously estimated. However, caution must be paid when assessing the risk of yield loss for wheat in this area since field validation of O3 impacts is still limited. © 2012 Elsevier Ltd. Source

Lahoz I.,Instituto Tecnico Y Of Gestion Agricola Itga | Fernandez J.A.,Technical University of Cartagena | Fernandez J.A.,CSIC - Center of Edafology and Applied Biology of the Segura | Migliaro D.,Technical University of Cartagena | And 2 more authors.
Scientia Horticulturae

Eight cardoon cultivars (six Spanish, one French and one Italian) were characterized by molecular, morphological and biochemical traits, thus exploiting the complementary nature of these methodological approaches. Molecular analysis was carried out using the inter-simple sequence repeat (ISSR) technique with twenty primers. Out of these, ten were polymorphic, producing a total of 98 DNA bands. A dendrogram, drawn on the basis of a genetic similarity matrix using the UPGMA algorithm, revealed that the 40 samples (5 plants per cultivar) could be classified into two major clusters with a Jaccard's index of 0.48. The morphological trait analysis showed that the quantitative morphological characters differed significantly among the eight cultivars and that they were influenced by environmental factors. Principal component analysis for qualitative morphological characteristics showed that a reduced number of descriptors could be used efficiently to discriminate among cultivars. The biochemical traits analysis showed that only seven compounds were able to establish differences among the analysed cardoon cultivars. The cultivars fell into different clusters when different characterization methods were used. Although the morphological and biochemical descriptors do not fully comply with the requirements needed for a reliable cultivar description, they can complete a molecular analysis obtained by ISSR markers for selecting cardoon cultivars. © 2010 Elsevier B.V. Source

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