Effects of understorey vegetation on tree establishment and growth in a silvopastoral system in northern Greece     

Stergios Gakis  Konstantinos Mantzanas  Dimitrios Alifragis  Vasilios P. Papanastasis  Athanasios Papaioannou  Dimosthenis Seilopoulos  Panagiotis Platis 《Agroforestry Systems》2004,60(2):149-157

The interaction between understorey plants and trees in a young silvopastoral system was studied in a sub-humid Mediterranean environment with cold winters in northern Greece. The experimental design was a split-split plot with three replications and included: three understorey treatments (grass, legume and control), two tree species (Acer pseudoplatanus and Pinus sylvestris) and two spacings (2.5×2.5 m and 3.5×3.5 m). The competition between herbaceous plants and trees resulted in significant differentiation in tree growth while their spacing did not produce any significant differences. The influence of trees on herbage yield either by plant species or spacing was not significant. During the early stages of establishment, a significant positive correlation was observed between sycamore growth and soil moisture, leaf weight, leaf area and leaf number as well as nitrogen and potassium concentration in leaves. Six years after planting the height increase of the sycamore trees was largest in the control treatment (415%), lowest in the grass treatment (134%) and intermediate (192%) in the legume treatment. Much higher was the increase obtained for the diameter, 161%, 207% and 536% respectively for the grass, legume and control treatments. The Scots pine trees grew faster than sycamore over the course of the experiment. Height increased by 397%, 351% and 400% and diameter by 518%, 443% and 683% respectively for the grass, legume and control treatments. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

A Spatially and Temporally Disaggregated Anthropogenic Emission Inventory in the Southern Balkan Region     

Anastasia Poupkou  Panagiotis Symeonidis  Ioannis Ziomas  Dimitrios Melas  Konstantinos Markakis 《Water, air, and soil pollution》2007,182(1-4):335-348

ICP Forest Monitoring data collected for more than 10 years made it possible to analyse key factors responsible for changes in forest conditions on a regional European scale. Observation routines may vary between different countries, which makes it difficult to gain more insight into stress-effect relationships. The effects on defoliation of Scots pine (Pinus sylvestris L.) of air concentrations and wet deposition of acidifying compounds, as well as effects of meteorological, site, stand and tree variables were investigated in Lithuania to test the hypothesis that spatial and temporal changes in pine defoliation were closely associated with atmospheric inputs of acidity. Over the period 1994–2004 crown defoliation of more than 8,000 pine trees was monitored in totally 45 stands distributed among three National Parks, where Integrated Monitoring Stations were situated. Air concentrations of SO2, and $ {\text{SO}}^{{{\text{2 - }}}}_{{\text{4}}} $ and $ {\text{NH}}^{{\text{ + }}}_{{\text{4}}} $ deposition, as well as spring and summer precipitation and mean winter temperature were shown to be the key factors affecting defoliation. The acidifying compounds accounted for nearly 58% of the variance in pine defoliation. Meteorological factors increased the degree of explanation to 65%, and stand and site variables to 79%.  相似文献   

Acquisition capability of the grapevine Flavescence dorée by the leafhopper vector Scaphoideus titanus Ball correlates with phytoplasma titre in the source plant     

Luciana Galetto  Dimitrios Miliordos  Chiara Roggia  Mahnaz Rashidi  Dario Sacco  Cristina Marzachì  Domenico Bosco 《Journal of pest science》2014,87(4):671-679

Flavescence dorée (FD) is one of the most economically important grapevine diseases in Southern Europe, and it is associated with phytoplasmas, phloem-limited wall-less bacteria. Recovery from disease naturally occurs in infected grapevines during the following seasons after infection. The capability of the leafhopper vector Scaphoideus titanus to acquire FD phytoplasma (FDP) from recovered and infected grapevines of Barbera and Nebbiolo varieties was investigated in North-western Italy vineyards monitored from 2007 to 2011. Pathogen concentration was quantified by real-time PCR in FDP-infected grapevines and broad beans, also used as source plants under controlled conditions, to correlate acquisition capabilities and phytoplasma titre in source plants. S. titanus acquired FDP from infected, but not from recovered, grapevines. FDP titre was higher in Barbera than in Nebbiolo and higher in summer than in spring, and acquisition efficiency and pathogen titre in source plants were positively correlated, both in field and laboratory conditions. Recovered plants do not represent a source of inoculum for the vector and therefore do not contribute to FDP spread. The inability of recovered plants to serve as FDP acquisition sources for the vector as well as the effect of the season and of the two grapevine varieties on the FDP acquisition efficiency are relevant results to re-design disease management practices, especially since insecticide treatments against the vector are not fully effective, and newly designed successful control strategies are required.  相似文献   

Residues of spiroxamine in grapes following field application and their fate from vine to wine     

Tsiropoulos NG  Miliadis GE  Likas DT  Liapis K 《Journal of agricultural and food chemistry》2005,53(26):10091-10096

Dissipation of the fungicide spiroxamine in grapes of two vine varieties, Roditis and Cabernet Sauvignon, exposed to field treatments was evaluated. Vines of a grape vineyard located in central Greece were sprayed once or twice with a commercial formulation of the fungicide at 30 g a.i./hL. Residues in grapes, must, and wine were determined by gas chromatography/IT-MS after extraction with cyclohexane-dichloromethane (9:1), with a limit of quantitation 0.02 mg/kg in grapes and 0.012 mg/kg in wine. Under field conditions, spiroxamine dissipation on grapes was faster during the first 2 weeks and then slower to the sixth week. About 7 days after application, half of the initial spiroxamine concentration remained on the grapes; the respective proportion at 42 days was about 10%. At 14 and 35 days, residues were lower than 0.44 and 0.22 mg/kg, respectively, values below the maximum residue levels set by the European Union (1 mg/kg). Spiroxamine residues transferred from grapes into the must and through the vinification process into the wine were also studied. Mean transfer factors of 0.26 and 0.55 were found from grapes into wine for the wines obtained without maceration and with maceration, respectively. Residues in wine, prepared from grapes with a spiroxamine content of 0.11-0.20 mg/kg, varied from <0.026 to 0.09 mg/kg. Spiroxamine diastereomer B was found to dissipate slower than diastereomer A in the field as well as during the vinification process.  相似文献   

Apple mealiness detection using fluorescence and self-organising maps     

Dimitrios Moshou  Stijn Wahlen  Reto Strasser  Ann Schenk  Herman Ramon 《Computers and Electronics in Agriculture》2003,40(1-3):103

The chlorophyll fluorescence kinetics of ‘Jonagold’ and ‘Cox’ apples, stored under different conditions to induce mealiness, were measured. Three different storage conditions were considered causing three mealiness levels: not mealy, moderately and strongly mealy. Also destructive measurements of the texture (firmness, hardness, juice content and soluble solids content) were done. Classification into different mealiness levels based on the fluorescence measurements was more performant than a classification based on the destructive measurements. To estimate the mealiness level in a non-destructive way from the fluorescence features, a number of different classifiers were constructed. Quadratic discriminants and supervised and unsupervised neural networks were tested and compared. The self-organising map gives promising results when compared with the multi-layer perceptrons and quadratic discriminant analysis. The different advantages of the constructed classifiers suggest that fluorescence can be used in an automatic sorting line to assess certain types of mealiness.  相似文献   

Strontium Absorption by Two Trifolium Species as Influenced by Soil Characteristics and Liming     

Tsialtas  John T.  Matsi  Theodora  Barbayiannis  Nikolaos  Sdrakas  Antonios  Veresoglou  Dimitrios S. 《Water, air, and soil pollution》2003,144(1-4):363-373

Strontium absorption by plants is specific to individual species and also depends on the underlying soil properties. The purpose ofthis study was to evaluate the effect of certain soil characteristics and liming on Sr absorption by twoTrifolium species. One-liter volume of two inorganic and three organic soilswere treated with a combination of three CaCO₃ levels, 0, 3.6 and 7.2 g, × two Sr levels, 50 and 100 mg, (treatments) in four replications. Trifolium repens L. was grown in thetreated soils, in pots, harvested twice, and Sr in theabove-ground biomass of each harvest and soil exchangeable Caof each treatment were determined. The experiment was repeatedwith Trifolium subterraneum L., harvested once. For bothspecies, Sr transfer factor (T.F.) values of the varioustreatments were calculated. Shoot Sr concentrations weresignificantly affected by soil characteristics and Sr additionrates and were greater in T. repens. In all cases, theSr concentrations of plants grown in the organic soils, whichwere characterized by higher exchangeable Ca and cationexchange capacity (C.E.C.) values, were lower than those ofplants grown in the inorganic soils. Among the organic soils,Sr concentrations of the plants grown in the soil with thehighest values of C.E.C., organic matter and exchangeable Cawere the lowest. Liming decreased significantly the Srconcentrations in T. repens and T. subterraneumgrown in the two acid soils, while the pH and exchangeable Cawere increased. Shoot Sr concentration (log scale) wassignificantly, negatively correlated with soil exchangeable Ca. Strontium T.F. values were quite similar between the two Sr application rates and were affected by the same soil characteristics.  相似文献   

Does the definition of the Mediterranean diet need to be updated?     

Serra-Majem L  Trichopoulou A  Ngo de la Cruz J  Cervera P  García Alvarez A  La Vecchia C  Lemtouni A  Trichopoulos D;International Task Force on the Mediterranean Diet 《Public health nutrition》2004,7(7):927-929

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Postharvest water relations in cut rose cultivars with contrasting sensitivity to high relative air humidity during growth     

Dimitrios FanourakisSusana M.P. Carvalho  Domingos P.F. Almeida  Olaf van KootenWouter G. van Doorn  Ep Heuvelink 《Postharvest Biology and Technology》2012,64(1):64-73

A constant high relative air humidity (RH) during cultivation can strongly reduce the vase life in some cut rose cultivars. We studied three contrasting cultivars in their tolerance to high RH in order to analyse in detail the water relations during postharvest and better understand this genotypic variation. Plants were grown at moderate (60%) and high (95%) RH, and cut flowers were placed in water immediately after cutting. Flowers of cv. Pink Prophyta grown at high RH did not open throughout vase life, while flower opening of cvs. Frisco and Dream was not affected by preharvest RH. Cultivation at high RH resulted in about 80% shorter vase life in Pink Prophyta, whereas in Dream and Frisco the negative effect was considerably smaller (15 and 9% shorter vase life, respectively). The shorter vase life and reduced flower opening of cut roses grown at high RH was due to a higher rate of transpiration both in the light and dark periods. It was found that the leaves of Pink Prophyta grown at high RH could partly close their stomata upon lowering of the water potential or when flower stalks were fed with abscisic acid, but stomata remained far more open than in leaves grown at moderate RH. The RH during cultivation did not affect stem hydraulic conductivity and its recovery after air emboli induction. Preventing vascular occlusion largely alleviated the high-cultivation-RH effect on vase life and flower opening, showing that the effect of high-cultivation-RH becomes only important if water uptake is limited.  相似文献   

Molecular typing of Brucella melitensis endemic strains and differentiation from the vaccine strain Rev-1   总被引：1，自引：0，他引：1  

Noutsios GT  Papi RM  Ekateriniadou LV  Minas A  Kyriakidis DA 《Veterinary research communications》2012,36(1):7-20

In the present study forty-four Greek endemic strains of Br. melitensis and three reference strains were genotyped by Multi locus Variable Number Tandem Repeat (ML-VNTR) analysis based on an eight-base pair tandem repeat sequence that was revealed in eight loci of Br. melitensis genome. The forty-four strains were discriminated from the vaccine strain Rev-1 by Restriction Fragment Length Polymorphism (RFLP) and Denaturant Gradient Gel Electrophoresis (DGGE). The ML-VNTR analysis revealed that endemic, reference and vaccine strains are genetically closely related, while most of the loci tested (1, 2, 4, 5 and 7) are highly polymorphic with Hunter-Gaston Genetic Diversity Index (HGDI) values in the range of 0.939 to 0.775. Analysis of ML-VNTRs loci stability through in vitro passages proved that loci 1 and 5 are non stable. Therefore, vaccine strain can be discriminated from endemic strains by allele’s clusters of loci 2, 4, 6 and 7. RFLP and DGGE were also employed to analyse omp2 gene and reveled different patterns among Rev-1 and endemic strains. In RFLP, Rev-1 revealed three fragments (282, 238 and 44 bp), while endemic strains two fragments (238 and 44 bp). As for DGGE, the electrophoretic mobility of Rev-1 is different from the endemic strains due to heterologous binding of DNA chains of omp2a and omp2b gene. Overall, our data show clearly that it is feasible to genotype endemic strains of Br. melitensis and differentiate them from vaccine strain Rev-1 with ML-VNTR, RFLP and DGGE techniques. These tools can be used for conventional investigations in brucellosis outbreaks.  相似文献   

Productivity of two stevia varieties under reduced irrigation and fertilization inputs     

Ioannis Vasilakoglou  Dimitrios Kalfountzos  Nikolaos Gougoulias  Charalampos Reppas 《Archives of Agronomy and Soil Science》2016,62(4):457-472

A 3-year field study was conducted in central Greece to determine the productivity of two stevia [(Stevia rebaudiana (Bertoni) Bertoni] varieties (‘Morita’ and ‘Candy-stevia’) under normal and reduced irrigation (100% and 75% of the evapotranspiration) and fertilization [1:0.8:1.1 or 1:0.4:0.8 N:P:K ratio in the first year and only N fertilization (100% or 74% of the recommended rate) in the second and third years] inputs. Averaged across years, stevia cv. Morita achieved greater dry leaf yield (3.48 t ha^?1) than the cv. Candy-stevia (2.85 t ha^?1). Irrigation and fertilization inputs did not significantly affect stevia cv. Morita dry leaf and steviol glycosides (stevioside plus rebaudioside-A) yields; however, decreasing irrigation and fertilization caused slight reduction of cv. Candy-stevia yields. In cv. Morita leaves, the concentrations of stevioside and rebaudioside-A ranged from 5.97% to 7.78% and 3.73% to 4.79%, respectively, while the corresponding concentrations in cv. Candy-stevia leaves were 8.21–9.36% and 3.89–6.33%. Conclusively, both stevia varieties could achieve satisfactory dry leaf biomass and steviol glycosides yield, even when grown under reduced irrigation (at 75% of evapotranspiration) and reduced N fertilization (74% of the recommended rate). Thus, stevia could represent an alternative crop to tobacco in the Mediterranean conditions.  相似文献