Gonzlez A.,IMIDRA |
Bermejo V.,CIEMAT |
Journal of Agricultural Science | Year: 2010
Drought is the main factor limiting the productivity of crops in Mediterranean areas. The introduction of physiological traits into crops that improve their tolerance to drought is necessary if yields under these conditions are to be efficiently improved. The effect of drought on different gas exchange variables, i.e. net photosynthesis (A), stomatal conductance (gs) and leaf chlorophyll concentration (Chl), and the relationship of these variables with yield were studied in 12 barley genotypes grown under irrigated and terminal drought conditions. The variable most sensitive to water deficit was gs (mean reduction 43% with respect to control conditions), followed by A (mean reduction 34%). The mean reduction of yield by terminal drought was 27%. A significant correlation was seen between these physiological traits and yield. The effect of water deficit on A, gs and Chl was smaller in the breeding lines than in the traditional varieties assayed, in agreement with the results found for yield. These results suggest a potential indirect selection of physiological characteristics in these breeding lines that allow greater tolerance to drought. The response of the different genotypes examined was not homogeneous across all the variables analysed. This variability is important in programmes aiming to obtain drought-tolerant genotypes via the optimization of traits such as those above. © 2010 Cambridge University Press.
Pena-Fernandez A.,University of Alcala |
Gonzalez-Munoz M.J.,University of Alcala |
Environmental Toxicology and Pharmacology | Year: 2014
Human hair is used as a biomonitor to evaluate the environmental exposure to contaminants in the individual. However, the use of human hair is controversial, mainly because reference levels for pollutants in hair have not yet been set. In the case of Spain, few biomonitoring studies have involved infants and children. A biomonitoring study was conducted to investigate the possible normal values of trace elements of toxicological concern in children aged 6-9 years from the city of Alcalá de Henares, Community of Madrid (Spain), following the methodology and strict inclusion criteria previously developed by our group. Levels of Al, As, Be, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Sn, Ti, Tl, V and Zn were monitored in scalp-hair from 117 healthy children (47 boys and 70 girls) between April and May of 2001. The levels of trace elements here described could be considered as possible "reference values" for children aged 6-9 years resident in the Community of Madrid. These values might also be selected as a preliminary screening tool to evaluate if a Spanish child has been exposed to any of the contaminants studied here. This study also investigated whether local urban topsoils were a source of metals for this population. © 2014.
Gonzalez M.,Center for Genetic Engineering and Biotechnology |
Gonzalez M.,Plant Health Institute |
Pujol M.,Center for Genetic Engineering and Biotechnology |
Metraux J.-P.,University of Fribourg |
And 3 more authors.
Molecular Plant Pathology | Year: 2011
Rhizoctonia solani Kühn is a soil-borne fungal pathogen that causes disease in a wide range of plants worldwide. Strains of the fungus are traditionally grouped into genetically isolated anastomosis groups (AGs) based on hyphal anastomosis reactions. This article summarizes aspects related to the infection process, colonization of the host and molecular mechanisms employed by tobacco plants in resistance against R. solani diseases. Taxonomy: Teleomorph: Thanatephorus cucumeris (Frank) Donk; anamorph: Rhizoctonia solani Kühn; Kingdom Fungi; Phylum Basidiomycota; Class Agaricomycetes; Order Cantharellales; Family Ceratobasidiaceae; genus Thanatephorus. Identification: Somatic hyphae in culture and hyphae colonizing a substrate or host are first hyaline, then buff to dark brown in colour when aging. Hyphae tend to form at right angles at branching points that are usually constricted. Cells lack clamp connections, but possess a complex dolipore septum with continuous parenthesomes and are multinucleate. Hyphae are variable in size, ranging from 3 to 17μm in diameter. Although the fungus does not produce any conidial structure, ellipsoid to globose, barrel-shaped cells, named monilioid cells, 10-20μm wide, can be produced in chains and can give rise to sclerotia. Sclerotia are irregularly shaped, up to 8-10mm in diameter and light to dark brown in colour. Disease symptoms: Symptoms in tobacco depend on AG as well as on the tissue being colonized. Rhizoctonia solani AG-2-2 and AG-3 infect tobacco seedlings and cause damping off and stem rot. Rhizoctonia solani AG-3 causes 'sore shin' and 'target spot' in mature tobacco plants. In general, water-soaked lesions start on leaves and extend up the stem. Stem lesions vary in colour from brown to black. During late stages, diseased leaves are easily separated from the plant because of severe wilting. In seed beds, disease areas are typically in the form of circular to irregular patches of poorly growing, yellowish and/or stunted seedlings. Resistance: Knowledge is scarce regarding the mechanisms associated with resistance to R. solani in tobacco. However, recent evidence suggests a complex response that involves several constitutive factors, as well as induced barriers controlled by multiple defence pathways. Management: This fungus can survive for many years in soil as mycelium, and also by producing sclerotia, which makes the management of the disease using conventional means very difficult. Integrated pest management has been most successful; it includes timely fungicide applications, crop rotation and attention to soil moisture levels. Recent developments in biocontrol may provide other tools to control R. solani in tobacco. © 2010 CIGB. Molecular Plant Pathology © 2010 BSPP And Blackwell Publishing Ltd.
Mauri P.V.,IMIDRA |
Manzanera J.A.,Technical University of Madrid
Acta Physiologiae Plantarum | Year: 2011
The production of ethylene and the endogenous content of polyamines (PAs) have been recorded during the early development, maturation and germination of holm oak (Quercus ilex L.) somatic embryos. Ethylene production was high in embryogenic callus, immature somatic embryos and in explants showing secondary embryogenesis, while it was lower in mature and germinating somatic embryos. A higher ethylene production was also associated to the process of secondary embryogenesis. The exogenous application of 1-amino-1-cyclohexane carboxylic acid was not significantly effective on the production of ethylene by holm oak somatic embryos. Total PAs were more abundant in embryogenic callus and in both somatic and zygotic immature embryos, decreasing later on in the mature and germination phases. Immature somatic embryos of holm oak and immature zygotic embryos contain high levels of spermidine (Spd), which decreased during maturation and germination. Spermine (Spm) concentration was lower than that of Spd. Spm was more abundant in embryogenic callus and immature zygotic embryos than in mature embryos. Ethylene production did not seem to interfere with PA metabolism. © 2010 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.
Ruiz-Colmenero M.,IMIDRA |
Bienes R.,IMIDRA |
Bienes R.,University of Alcala |
Eldridge D.J.,University of New South Wales |
Marques M.J.,Autonomous University of Madrid
Catena | Year: 2013
Land degradation, and soil and nutrient loss, are significant environmental problems in semi-arid agricultural environments in the Mediterranean Basin. One land use that is particularly associated with the highest rates of erosion in Spain is extensive vineyards. We examined the effectiveness of two cover crops for improving soil physical properties and reducing erosion in a vineyard located in the Henares River basin southeast of Madrid, Spain. We assessed erosion from three replicate plots of 2m2 each with three treatments that comprised: traditional tillage, permanent cover of Brachypodium distachyon and spring-mown crop of Secale cereale. Erosion plots under traditional tillage yielded substantially more erosion (5.88tha-1yr-1) than Brachypodium (0.78tha-1yr-1) or Secale (1.27tha-1yr-1). While the concentration of SOC in sediments was greater for the cover crops, the mass-corrected loss of SOC was greater under tillage (0.06tha-1yr-1) than under Brachypodium or Secale (0.02tha-1yr-1). Root biomass was two- to four-times greater under the vegetation treatments. Our measure of aggregate stability for the tillage treatment remained between 7.9 and 5.4 drops over the four years of study and values for both cover crops exceeded that for Tillage by the end of the second year. The vegetation cover treatments increased SOC by 1.2% and intrapedal SOC by 10-60% compared with Tillage. By the end of the study, steady-state infiltration in the cover treatments was 45% greater than that under tillage, with the largest increase under Brachypodium. We attribute the greater infiltration on cover treatments to a greater abundance of larger pores on vegetated compared with tilled plots. Our study reinforces the notion that there are considerable benefits of using cover crops in rainfed vineyards, not only for prevention of soil erosion, but to enhance soil condition and potentially reduce the heavy reliance on industrial fertilisers. © 2012 Elsevier B.V.