Lukas V.,Mendel University in Brno |
Moreno F.R.,Research Center la Orden Valdesequera |
Neudert L.,Mendel University in Brno |
Dryslova T.,Mendel University in Brno
Precision Agriculture 2011 - Papers Presented at the 8th European Conference on Precision Agriculture 2011, ECPA 2011 | Year: 2011
The knowledge of spatial variability of nutritional status in plants is important for adequate variable rate application of fertilizers. In this paper are presented initial results of an ongoing study which verify using of multispectral imagery to estimate a continuous image of nutritional status in winter wheat. Verification was carried out in 2010 at two different locations with areas of 53 and 38 ha in the Czech Republic. Plant inorganic analysis (content of N, P, K, Mg, Ca and S) and ground measurement of LAI were carried out in winter wheat at BBCH 30 in regular sampling grid 150 × 150 m. Results were related with the broadband multispectral images (G, R, NIR bands, NDVI index) from an aerial survey using two techniques, multiple linear regression and decision trees. Both methods shown promising results, reaching values of 0.83 for the R square with the multiple linear regression and a hit rate of 57.8% with the decision trees.
Moral F.J.,University of Extremadura |
Terron J.M.,Research Center la Orden Valdesequera |
Silva J.R.M.d.,University of Evora
Soil and Tillage Research | Year: 2010
Site-specific management promotes the identification and management of areas within the field, which represent subfield regions with homogeneous characteristics (management zones). However, determination of subfield areas is difficult because of the complex combination of factors which could affect crop yield. One possibility to capture yield variability is the use of soil physical properties to define the management zones as they are related to plant available water. With the aim of characterizing the spatial variability of the main soil physical variables and using this information to determine potential management zones, soil samples were taken from 70 locations in a 33-ha field in Badajoz, southwestern Spain. Firstly, accurate spatial distribution maps of the soil attributes were generated by using regression kriging as the most suitable algorithm in which exhaustive secondary information on soil apparent electrical conductivity (ECa) was incorporated. ECa measurements were carried out with a Veris 3100 operating in both shallow (0-30 cm), ECs, and deep (0-90 cm), ECd, mode. Clay, coarse sand and fine sand were the soil physical properties which exhibited higher correlation with ECa (positively correlated with the finer texture component, clay, and negatively correlated with the coarser ones, coarse and fine sands), particularly with ECs. Thus, this was the secondary variable used to obtain the kriged maps. Later, principal component analysis and fuzzy cluster classification were performed to delineate management zones, resulting in two subfields to be managed separately. This number of subfields was determined using the fuzzy performance index and normalized classification entropy as the way to optimize the classification algorithm. © 2009 Elsevier B.V. All rights reserved.
Vazquez F.M.,Research Center la Orden Valdesequera |
Jarvis C.E.,Natural History Museum in London
Taxon | Year: 2010
The typification of ten Linnaean names of taxa belonging to the Valerianaceae is discussed. Lectotypes are designated from the Linnaean herbarium at LINN (Valeriana dioica, V. locusta var. discoidea, V. phu, V. tripteris), the Burser Herbarium at UPS (V. montana, V. tuberosa), and from the Clifford Herbarium at BM (V. rubra). An illustration in a pre-Linnaean work is designated as the lectotype of both V. locusta var. mutica and V. locusta var. pumila. Valeriana mixta, often treated as ambiguous, is discussed and will be proposed for formal rejection. Each type choice made here maintains the present usage of the corresponding Linnaean name.
Munoz-Costa A.,Research Center la Orden Valdesequera |
Calleja-Alarcon J.A.,Autonomous University of Barcelona
Forest Systems | Year: 2013
Aim of study: The present work provides novel insights on factors (either intrinsic or extrinsic) that trigger sprouting in woody species living at range margins. We aim to explain the inter-individual variability in the multi-stemmed architecture of Prunus lusitanica L., an Iberian evergreen relict tree related to the Tertiary flora. Area of study: Northeastern Mediterranean mountains of the Iberian Peninsula, the Northeast limit of the global distribution of the species. Material and methods: We gathered data on two modes of vegetative reproduction, basal and layering sprouts, in 288 clumps of Prunus lusitanica from four populations. We modeled and analyzed the effect of environmental factors (topography, canopy cover, soil moisture and disturbances) and plant size (diameter at breast height) on sprouting by means of Generalized Linear Model and other statistical approaches. Main results: Plant size arises as the principal factor to explain the variability of the numbers of both types of sprouts yet it is not a trigger factor. Natural and anthropogenic disturbances promote basal and layering shoots, while tree canopy is mainly relevant for basal shoots, and slope and soil moisture are significant factors for layering shoots. Research highlights: The multi-stemmed architecture of P. lusitanica at the Northeastern limit of its worldwide distribution is triggered by local environmental factors and disturbances. Each external factor shows different levels of influence on the variability and type of vegetative reproduction yet the intensity of the response is driven by the size of the largest trunk of each clump.
Ramos S.,University of Extremadura |
Rincon S.,Junta de Extremadura |
Vazquez F.M.,Research Center la Orden Valdesequera
Annales Botanici Fennici | Year: 2010
Astragalus gines-lopezii is a perennial herb, endemic to the south of the Iberian Peninsula. It has been classified as 'Endangered' by the Extremadura Regional Catalogue and placed in the equivalent category (EN D) of the National Red List because only one population in the world is known. Conservation of A. gines-lopezii requires a greater understanding of its population size, seed ecology and germinationconditions. The latter issues are particularly important when establishing a reintroduction programme. This species was observed in nine colonies on the same mountainside, the largest of which consists of 60plants. In this study, we compare the ability of the seeds to germinate under various conditions. Unlike most other members of the Fabaceae, the seeds of A. gines-lopezii do not need physical or chemical pre-treatment in order to germinate; instead they require a photoperiod for optimal germination. This study will facilitate a more in-depthunderstanding of this rare and poorly known species. © Finnish Zoological and Botanical Publishing Board 2010.