Mediterranean agro-towns as a form of cultural dominance

Wetensch. publicati

Respuesta fisiológica de un cultivo de melón (Cucumis Melo L.) a distintas dosis de riego

En este trabajo se presentan los resultados de resistencia estomática (Rs) obtenidos en diferentes momentos del día y al alba a lo largo del desarrollo del cultivo, con el fin de valorar la respuesta fisiológica de las hojas de melón sometido a distintas dosis de riego, así como su relación con la evolución del índice de área foliar (LAI) y el rendimiento. Los niveles hídricos se determínaron en función de las necesidades de riego calculadas (NRc) a partir de la evapotranspiración del cultivo, ensayándose cuatro tratamientos correspondientes a 1,25 NRc ; 1,00 NRc ; 0,75 NRc y 0,50 NRc. Los estomas del haz y del envés de la hoja no respondieron de forma similar a las distintas condiciones del medio, obteniéndose valores de Rs superiores en el haz. La dosis de riego no afectó de forma significativa a este parámetro en las distintas fechas de medida al alba. Tampoco hubo diferencias entre los valores registrados a intervalos de 2 h a lo largo del día, excepto el 12 de agosto de 1997, 95 días después de la emergencia (DDE), a las 12:00 hora solar en el envés de la hoja, cuando la Rs del tratamiento más deficitario (TR4) fue significativamente mayor. Sin embargo, el déficit hídrico produjo una reducción significativa del LAI y del rendimiento, por lo que la medida de Rs no es un buen indicador del estado hídrico de la planta cuando el riego se aplica diariamente con dosis deficitarias

Spectral discrimination of wild oat and canary grass in wheat fields for less herbicide application

Wheat, Triticum durum L, is a major cereal crop in Spain with over five million ha grown annually. Wild oat, Avena sterilis L., and canary grass, Phalaris spp., are distributed only in patches in wheat fields but herbicides are applied over entire fields, thus leading to over-application and unnecessary pollution. To reduce herbicide application, site-specific management techniques based on weed maps are being developed to treat only weed patches. Intensive weed scouting from the ground is time-consuming and expensive, and it relies on estimates of weeds at unsampled points. Remote sensing of weed canopies has been shown to be a more efficient alternative. The principle of weed remote sensing is that there are differences in the spectral reflectance between weeds and crops. To test this principle, we studied spectral signatures taken on the ground in the visible and near-infrared windows for discriminating wheat, wild oat and canary grass at their last phenological stages. Late-season phenological stages included initial seed maturation through advanced maturation for weeds, and initial senescence to senescent for wheat. Spectral signatures were collected on eight sampling dates from April 28 through May 26 using a handheld field spectroradiometer. A stepwise discriminant analysis was used to detect differences in reflectance and to determine the accuracy performance for a species classification as affected by their phenological stage. Four scenarios or classification sets were considered: wheat-wild oat-canary grass, with each species represented by a different group of spectra; wheat and grass weeds, combining the two weed species into one spectral group; wheat and wild oat with each represented as a single group, and finally, wheat and canary grass. Our analysis achieved 100% classification accuracy at the phenological stages of initial seed maturation, and green and advanced seed maturation and partly green for weeds and wheat, respectively, between the dates of April 28 and May 6. Furthermore, we reduced the number of hyperspectral wavelengths to thirteen out of 50. Multispectral analysis also showed that broad wavebands corresponding to those of QuickBird satellite imagery discriminated wild oat, canary grass and wheat at the same phenological stages and dates. Our findings are very useful for determining the timeframe during which future multispectral QuickBird satellite images will be obtained and the concrete wavelengths that should be used in case of using airborne hyperspectral imaging. Accurate and timely mapping of the spatial distribution of weeds is a key element in achieving site-specific herbicide applications for reducing spraying volume of herbicides and costs

Geographic distribution of human Blastocystis subtypes in South America

Blastocystis is a cosmopolitan enteric protist colonizing probably more than 1 billion people. This protozoan exhibits genetic diversity and is subdivided into subtypes (STs). The aim of this study was to determine the distribution of Blastocystis STs in symptomatic and asymptomatic human samples from different countries of South America. A total of 346 fecal samples were genotyped by SSU rDNA showing ST1 (28.3%), ST2 (22.2%), ST3 (36.7%), ST4 (2%), ST5 (2.3%), ST6 (2%), ST7 (2.3%), ST8 (0.6%), ST12 (0.9%) and a novel ST (2.7%). These findings update the epidemiology of Blastocystis in South America and expand our knowledge of the phylogeographic differences exhibited by this stramenopile. © 2016 Elsevier B.V

Geographic distribution of human Blastocystis subtypes in South America

Blastocystis is a cosmopolitan enteric protist colonizing probably more than 1 billion people. This protozoan exhibits genetic diversity and is subdivided into subtypes (STs). The aim of this study was to determine the distribution of Blastocystis STs in symptomatic and asymptomatic human samples from different countries of South America. A total of 346 fecal samples were genotyped by SSU rDNA showing ST1 (28.3%), ST2 (22.2%), ST3 (36.7%), ST4 (2%), ST5 (2.3%), ST6 (2%), ST7 (2.3%), ST8 (0.6%), ST12 (0.9%) and a novel ST (2.7%). These findings update the epidemiology of Blastocystis in South America and expand our knowledge of the phylogeographic differences exhibited by this stramenopile. © 2016 Elsevier B.V