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Beneki C.,Technological Educational Institution of Ionian Islands | Eeckels B.,Les Roches-Gruyere University of Applied Sciences | Leon C.,University Center
Journal of Forecasting | Year: 2012

We present and apply singular spectrum analysis (SSA), a relatively new, non-parametric and data-driven method for signal extraction (trends, seasonal and business cycle components) and forecasting of UK tourism income. Our results show that SSA slightly outperforms SARIMA and time-varying-parameter state space models in terms of root mean square error, mean absolute error and mean absolute percentage error forecasting criteria. Copyright © 2011 John Wiley & Sons, Ltd. Source


Bouchagier P.,Technological Educational Institution of Ionian Islands | Efthimiadis P.,Agricultural University of Athens
Journal of Agronomy | Year: 2010

The aim of the study was to investigate the influence of bermudagrass on growth components, physiology parameters (stomatal aperture, leaf transpiration, carbon dioxide intake, leaf temperature, Fv/Fm values and net assimilation rate) and concentration of important nutrients (N, P, K, Mg, Ca) in leaves and roots of cotton. Cotton seedlings and bermudagrass plantlets were growing adjacently in a Hoagland's nutrient solution of 1/2 strength, which was continuously circulated. Under the influence of bermudagrass, cotton suffered significant reduction of stomatal aperture, leaf transpiration, CO2 intake, Fv/Fm values, net assimilation rate and significant increase in leaf temperature. No differences were recorded between control and treatment in nutrient concentration in leaves. On the contrary, in cotton roots due to the influence of bermudagrass, Mg was increased by 29.2, P by 63.2 and Ca by 297.4%. Consequently the growth of plants in treatment was significantly inferior than control. Reduction was recorded at 54.6% for stem dry matter, at 35.5% for stem diameter, at 55.3% for leaves dry matter and 46.2% for root dry matter. Growth inhibition and deterioration of photosynthesis components (specifically Fv/Fm values) indicate that cotton suffered serious allelopathic stress due to the weed influence. Stress effect was pronounced although plants were growing in the nutrient solution, were no adverse factor to limit growth was observed. The allelopathic effect was exhibited by the weed, although it was not stressed in the nutrient solution. Dilution of allelochemicals in a high volume solution didn't reduce activity of allelochemicals. © 2010 Asian Network for Scientific Information. Source


Filippou P.,Cyprus University of Technology | Bouchagier P.,Technological Educational Institution of Ionian Islands | Skotti E.,Technological Educational Institution of Ionian Islands | Fotopoulos V.,Cyprus University of Technology
Environmental and Experimental Botany | Year: 2014

Ailanthus altissima (Miller) Swingle (family Simaroubaceae), commonly known as the 'Tree of Heaven', grows aggressively in harsh environments where it invades abandoned fields or cracked city sidewalks. The present study deals with the adaptation of defence mechanisms of A. altissima seedlings subjected to two of the most important abiotic stress factors worldwide, drought and salinity. Salinity-stressed A. altissima seedlings were obtained by watering the plants with two different NaCl concentration solutions (150 and 300mM) for 48h, while drought-stressed plants were obtained after withholding watering for 14d. Physiological parameters, reactive oxygen/nitrogen species and malondialdehyde content measurements in stressed plants indicated the abiotic stress factor-specific regulation of its defence response. Moreover, the content of the osmoprotective molecule proline was also affected by both stresses in parallel to the oxidative/nitrosative markers. Nitrate reductase enzymatic activity and protein content involved in nitric oxide biosynthesis, δ1-pyrroline-5-carboxylate synthetase enzymatic activity involved in proline biosynthesis, as well as the activity of H2O2-generating and scavenging enzymes (superoxide dismutase and catalase, respectively), provided further biochemical support for the specific abiotic stress tolerance mechanism of this invasive plant species. © 2013 Elsevier B.V. Source

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