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The incidence of Zucchini yellow mosaic virus (ZYMV) was monitored in the south Moravian region of the Czech Republic during 1997-2001. Crops of gherkin, squash, zucchini and cucumbers were found infected with ZYMV, manifested by symptoms of severe stunting and yellowing with deformed leaves and fruits. Twenty to eighty percent of infected plants were recorded. Six isolates of ZYMV from four localities were differentiated on indicator plants; three of them were maintained as being typical for differences in pathogenicity. Overwintered weed species were tested for the presence of the virus. ZYMV was detected by ELISA in one plant of Tripleurospermum maritimum out of 46 tested, and in two plants of Stellaria media out of 29 tested in 2001. Such tests were repeated in 2002, and ZYMV was detected in three plants of T. maritimum out of 45 tested, in three plants of S. media out of 52, and in two plants of Trifolium repens out of 17 tested. The virus was successfully transmitted from T. maritimum, S. media and T. repens to indicator plants of Cucurbita pepo convar. giromontiina. Back-transmission of ZYMV was proved by ELISA, electron microscopy and symptoms. T. maritimum was found to be a new natural host of ZYMV.

Arabidopsis is universally resistant as a species to many crop pathogens, including examples from other crucifers suchas Albugo candida and Hyaloperonospora parasitica from Brassica oleracea. This species level trait could potentiallyprovide a source of durable disease resistance in crops if examples can be found which are amenable to molecular geneticcharacterization. Our research has developed from the observation that null mutation in Arabidopsis of a defense regulatorygene EDS1 (enhanced disease susceptibility) is susceptible to isolates of A. candida and H. parasitica from brassica.EDS1 is required by a major structural class of R-genes to confer resistance in Arabidopsis. We have therefore focusedon identifying R-genes in Arabidopsis that are responsible for conferring resistance to brassica pathogens.

Peach latent mosaic viroid (PLMVd) is widespread in peach all over the world. It has never been reported from the Czech Republic. That is why we adapted specific and sensitive method for its detection, PCR, to be able to prove its possible occurrence and for certification purposes. Primers PLMVdR, PLMVdF1 and PLMVdF2 were designed on the basis of published RNA sequences. Products of amplification are 208 and 114 bp long for PLMVdF1 and PLMVdF2, respectively. Four PLMVd isolates from Dr Di Serio (CNR Bari) were used as standards. Potato spindle tuber viroid and Hop latent viroid infected plant material and also healthy material were used to check detection specifity. Both RNA extraction from plant material and PCR were optimalized so that this method of PLMVd detection can also be used for certification purposes.

From 2000 to 2001 the population dynamics of Psammotettix alienus Dahlb. were recorded using a sweep-net or a biocoenometer. The investigations were carried out in Zscherben near Halle (Middle German Dry Region). The imagines of the first generation of P. alienus could be observed for the first time at the beginning of May (2000) and at the end of May (2001), respectively. According to our results, in this area three generations of P. alienus are developed. In both years of our observations the barley-strain of Wheat dwarf virus (WDV) occurred. The main important infections appeared in autumn. Furthermore, during the whole period of our investigations the percentage of viruliferous individuals which were caught was recorded by means of a biological test. In June this percentage achieved 84.0% (2000) and 76.7% (2001), respectively. In the course of summer months of both years the percentage of viruliferous P. alienus decreased. In autumn of the year 2000 an increasing portion followed once again. However, in the year 2001 a continual reduction from > 70% in June to < 5% in late autumn could be observed.

As tobacco black shank epidemics caused by Phytophthora nicotianae occurred in central Italy in the late 1990s, fungal antagonists of the pathogen were searched in the rhizosphere of tobacco plants. Isolates of Aspergillus sydowii, Fusarium chlamydosporum, Gliocladium roseum, Penicillium brevicompactum, P. chrysogenum, Scopulariopsis candida and Trichoderma harzianum were recovered. Antagonism of these isolates toward P. nicotianae was evaluated in vitro: even if no hyphal interactions were observed in dual cultures, aberration in mycelial growth and morphology of sporangia occurred in most cases. Unlike those of T. harzianum, concentrated culture filtrates of A. sydowii, F. chlamydosporum, G. roseum, P. brevicompactum, P. chrysogenum, inhibited growth of all P. nicotianae isolates tested, while culture filtrates of S. candida caused aberrant mycelial growth.

In the period 1996-1999 field trial was performed in Obory near Kwidzyn on heavy textured Fluvisols. The experiment was aimed to determine yield, chemical composition, heat value of wood of six genotypes of willow coppice in relation to cutting frequency and on determining the costs and profitability of willow production on arable land for purposes of energy generation. Yield of wood dry matter in one-year cutting cycle amounted to 14.09 t/ha/year 1 and significantly increased to 16.05 and 21.55 t/ha/year when harvesting was performed in two and three years cycle, respectively. The highest yield was found for Salix viminalis 082 form cut in three years cycle and it amounted to 26.44 t/ha/year 1. Stems of Salix sp. cut every three years showed the lowest water content (46.05%), high heat value 19.56 MJ/kg dry matter and the highest content of cellulose (55.94%), lignins (13.79%) and hemicelluloses (13.96%). High yielding potential of Salix sp. and high content of cellulose and lignin in wood make this crop very prosperous as a feedstock for bioenergy production. The highest profit from the willow plantation was obtained in case of harvest every three years at 578.76 EUR/ha/year.

The main goal of this work was to calibrate and evaluate the CERES-Barley and CERES-Wheat crop models. The experimental fields used for the model evaluation are situated in three different production regions (maize, sugar beet and potato main growing regions, respectively) with altitudes of 179, 204 and 560 meters above the sea level. Grain yield and date of anthesis together with maturity dates served as reference for the model evaluation. Two evaluation approaches were tested in this study. The first one uses historical data series and it is based on long-term field experiments with capability to reflect interannual weather variability. The second approach uses results of one-year multiple treatment experiment. The model evaluation is then based on a set of treatments differing e.g. in sowing date or an amount of used nitrogen fertilizer. Grain yields simulated by both models are acceptable when compared with experimental results: the coefficient of determination for historical series varied from 0.69 to 0.86 for evaluation of CERES-Barley at the three examined sites and reached values of 0.60 and 0.86 for the CERES-Wheat model at two experimental sites. The lower coefficient of determination of the wheat model was recorded at the locality with the highest altitude and coldest winter conditions. There, also the worst reliability of simulated phenological development was noted. At the second locality where the CERES-Wheat model was tested and at all three localities where CERES-Barley was applied, the simulated duration of vegetation period and anthesis dates were relatively accurate and yielded strong statistical correlation. The one-year multiple treatment experiment proved to be useful to determine the models sensitivity to differences in crop management. The combination of both approaches seems to be the best solution for evaluation of similar crop models if the detail long term experimental data are not available.

A model experiment was conducted to compare hand extraction (elutriation) under running water and elutriation using the device Analysette 3, the two methods for estimation of weed seedbank in the soil. Technical parameters have been assessed for efficient operating of the device. We studied the time required for elutriation of soil samples and the time for collecting, counting and identifying the separated seeds. No significant difference in the effect of the used elutriation method on results of qualitative and quantitative estimation of weed seedbank densities has been found at any of the three locations differing in soil texture (silty loam, loam and clay loam soil). The time necessary for elutriation of soil samples was highly significantly shorter if the device was used, by 35.5 to 42.9% depending on soil texture vs. hand elutriation. The shortest time was assessed for silty loam soil. By contrast, the time needed for selecting, counting and identifying seeds was shortest for clay loam soil. This time was 46 and 92% longer for loam and silty loam soil, respectively. These differences were statistically highly significant. Comparing the seedbank in the soil, a significantly lower number of weed seeds as well as species was found on silty loam soil vs. the two locations with heavier soils. Amaranthus retroflexus was a dominating species at all locations, and on silty loam soil also Chenopodium album. Of a total number of 32 weed species detected in our experiment, 28 were annual and only four perennial (Cirsium arvense, Elytrigia repens, Rumex obtusifolius and Sonchus arvensis).

Internal and external entropy are indicators of evaluation of the success of the firm management. The evaluation of the file of the chosen agricultural firms shows, that the level of internal and external entropy is not too high for the future dynamics and development. Competitiveness of the evaluated firms can be influenced especially by problematic level of their interior social situation (it means social subsystem measured with the help of the internal entropy) that is connected with a not very efficient management of the human resources.

Even ten years after the revolution in 1989, Slovak agriculture is characterized by the predominant position of cooperatives. There were shifts towards other types of agricultural entrepreneurship, and some of these trends we documented in our article, based on the data gained by surveying agricultural enterprises. We drew a conclusion that cooperatives are more labor demanding. This also means that they still preserve a social role as a main employer in rural areas. Our paper also differentiates between Southern and Northern (less favorable for agriculture) regions, represented by the Nitra and Žilina region, respectively. We examined soil quality, labor intensity, wages, and finally main crops yields in these two regions.

The author deals with the influence of cost taxes on the development of agriculture, mainly those taxes, which have an important impact from the point of view of forming an entrepreneurial environment in agriculture. Among the cost taxes, the impact of land tax, building tax, road tax and income tax is most important. The analysis also deals with the contribution to the insurance funds related to employees. This contribution can also be considered as a taxation. The article also gives a prediction of the expected development of the consequences of the accepted tax law changes.

Forty two peach-nectarine (Prunus persica [L.] Batsch.) varieties (i.e Spring Time, Precocissima Morettini, Southhaven, Halehaven, Blazing Gold, Cardinal, Gialla Precoce Morettini, Dixired, Fertilia Morettini, Golden Jubilee, Coronet, Red Haven, Red Globe, Cotonia Massima, Morettini 5/14, Peach of Station, Alexander, Early Elberta, Elberta of Middle Season, Beauty of Georgia, J.H. Hale, Late Elberta, Gold Drest, Morettini No. 1, Jerseyland, Desert Gold, Red Cup, Spring Crest, Loring, June Gold, Merril Gem Free, Early Red, Red Skin, Merril Fortyminer, Roubidoux, Fantasia, Sunhaven, Flavour Top, Merril Franciscan, Blake, Fairtime, Fayette) were studied for 12-18 years in three experimental orchards of Peripheral Agricultural Research Station of Rhodes (PARSR). Their degree of adaptation to the soil and climatic conditions of PARSR was evaluated in terms of yield per tree, time of bloom, time of fruit ripening, fruit quality etc. These results have been compared with related experimental data recorded at the Pomology Institute (PI) at Naoussa. The results indicate that: many peach-nectarine varieties with quite high chilling requirements (Loring, Blake) gave satisfactory yield in PARSR, where the mean average of temperatures below 7°C over one decade was found to be 147 hours (range 52-226). Some peach-nectarine varieties in experimental orchards of PARSR ripened more than ten days earlier (Desert Gold, Early Red, Peach of Station, Loring, Merril Gem Free), of others at about the same time (Coronet, Cotonia Massima, Red Skin, Fertilia Morettini, Red Globe) and at others on a later date (Merril Fortyminer, Early Elberta, J.H. Hale, Cardinal, Southhaven) than they would ripen in northern Greece (PI). Similar differences were also found for the time of blooming.

The paper presents a method for the derivation of total timber production and of increments in value units, particularly in net financial yield for spruce stands damaged by crown defoliation after their dieback. The value production was derived by means of value growth models of undamaged stands and models for the adjustment of volume and qualitative production of damaged and died stands. Changes in timber quality after tree drying and changes in the production of damaged stands compared with undamaged ones are illustrated in tables and graphs. The changes are expressed by means of the indexes of total mean increment and total current increment. They depend mainly on the degree of stand damage expressed by crown defoliation, age and yield class of stand, the age of stand when the damage started and duration of damage. The value of damaged stands after their dieback is lover minimally by 50% than before their dieback. It is caused mainly by deteriorated quality of timber from dead trees in stand.

Chrysopids and Hemerobiids were studied using Malaise traps in young spruce forests in the eastern part of the Czech Republic. A total of 12 species were found. The most abundant species were eurytopic Chrysopa carnea, Chrysopa perla, Hemerobius humulinus and Hemerobius pini associated with conifers. The seasonal flight activity of these species is discussed.

Plum pox virus (PPV) is widely distributed in plums and myrobalans in western, central and easternBohemia, in north-western, central and north-easternMoravia of theCzechRepublic. In southernBohemia and partly also in southernMoravia there is only a low and sporadic incidence. Naturally growing plums and myrobalans, and plums growing along roads were found to be the main sources and reservoirs of PPV infection. This high incidence in naturally growing plum and myrobalan trees makes it impossible to grow plum cultivars that are susceptible to PPV; only resistant cultivars can be grown in this country. In blackthorns the occurrence of PPV is limited to the regions with high and long-term presence of the virus. Therefore, we can conclude that blackthorn is not the primary, but a secondary source of PPV. On the other hand, sweet and sour cherries at localities of central and westernBohemia, and of southernMoravia are PPV-free. Till now the presence of strain PPV-C was not proved in theCzechRepublic. Strain PPV-M was proved only in two plum and one damson trees. It was also found in one apricot and one peach orchard planted with imported nursery material. Strain PPV-M appears to have been introduced recently and is absent from or has a very low incidence in spontaneous PPV hosts, while the widespread and long-term dissemination of strain PPV-D may indicate that it originated in the Czech Republic.

Resistance to Potato mop-top virus (PMTV) was studied in Nicotiana benthamiana and potato (Solanum tuberosum cv.Saturna) transformed with the coat protein (CP) gene of PMTV. In N. benthamiana plants mechanically inoculated withPMTV, RNA2 was detected in leaves and roots in several plants in the absence of RNA3. When N. benthamiana wasgrown in infested soil, viral RNA was detected in roots, but no systemic movement of PMTV to above-ground parts wasobserved. The incidence of PMTV infections was reduced in the CP-transgenic potato plants grown in an infested fieldin Sweden. However, in infected tubers, all three virus RNAs were detected.

In our previous study of Claviceps purpurea three populations were found: G1 on open localities, G2 from shady or wet habitats and G3 on Spartina stands of coastal salt marshes. The latter two are also chemoraces. In the Czech Republic, isolates of G1 and G2 were found. The ability of four isolates representing these populations to infect and develop sclerotia on different host species (Holcus lanatus, Helictotrichon pubescens, Phalaris arundinacea, Dactylis glomerata, Arrhenatherum elatius, Bromus inermis, Bromus erectus, Elytrigia repens, Avenella flexuosa, Lolium perenne, Poa nemoralis, Poa annua, and different cultivars of Poa pratensis) was studied along with their alkaloid production. P. pratensis and D. glomerata were infected by all the isolates and sclerotia were formed by isolates 207 (G1) and 434 (G2), and on two P. pratensis cultivars even by 481 (G3). Infection ability (formation of sphacelial stage and honeydew) was less host-restricted than formation of mature sclerotia. G2 and G3 strains infected A. flexuosa without sclerotia formation. L. perenne was infected only once by strain 207 (G1) without sclerotia formation. P. annua (natural host of G2), was infected by all isolates, but no sclerotia were formed even with G2 strains. From the two G2 isolates, strain 434 from Dactylis formed sclerotia on five host species, whereas isolate 475 originating from Phragmites stand formed only sphacelia. Composition of alkaloid mixture produced in sclerotia of the same strain from various hosts confirmed that host plant does not influence the type of alkaloids produced, only their ratio.

It is indispensable to have accurate and speedy method of nematodes detection considering their great deal of malignancy nematodes. For identification of Meloidogyne incognita genetic primers were designed and the procedure was attested by Polymerase Chain Reaction.

Side effect of two herbicides (iodosulfuron-methyl/Na + mefenpyr-diethyl = Husar and isoproturon = Tolkan) on micromycetes on winter wheat was study. Herbicide treatment reduced the whole number of fungi and number of genera in phyllosphere. It reduced number of the rhizosphere fungal genera, too. Population of Chrysosporium sp. markedly increased after Husar application, whereas population of Trichoderma harzianum was markedly reduced. Tested herbicides inhibited the development of Fusarium avenaceum on wheat leaves. Iodosulfuron-methyl/Na + mefenpyr-diethyl significantly reduced the growth of F. avenaceum in vitro.

In order to identify components of the defence signalling network that may contribute to the establishment of disease resistance, we generated a novel PR-1::Luciferase transgenic line which was deployed in an imaging based screen to uncover novel defence-related mutants. Approximately, 5000 ethylmethane sulfonate (EMS) lines and 30 000 activation tagged lines were generated and screened for enhanced LUC activity via ultra low light imaging.

Resistance to root knot nematode M. chitwoodi has been identified in the wild tuber-bearing Solanum species, S. bulbocastanum. Three pathotypes were identified suggesting at least two different genetic factors for virulence and resistance in the pathogen and the host species, respectively. Roots of S. bulbocastanum were infested with two isolates of M. chitwoodi differing in virulence. The infection process was monitored by histological examination of roots allowing time points to be identified. cDNA libraries were constructed from infected root tissue using Suppression Subtractive Hybridisation (SSH) to enrich for transcripts from either compatible or incompatible interactions, at three days and seven days post infection. Both plant and nematode genes, which may be important during the host/parasite interaction, were identified.

The laboratory incubation with glucose treatment was carried out in order to estimate the possible effects of increased microbial activity on heavy metal availability. The soils from vicinity of a lead smelter operating for more than 200 years were used for the experiment. The DTPA-extractable heavy metal contents increased after glucose addition and mostly reached the highest values the second day of the incubation. The comparative study, where the chloroform fumigation was used prior to the incubation in order to decrease the microbial activities, showed especially from second day of incubation significantly lower DTPA-extractable metal contents compared to non-fumigated treatments. The interactions among the maximum possible availability of DTPA-extractable heavy metal fractions and native soil microbial characteristics were studied in differently contaminated arable and grassland soils. Irrespective of different heavy metal contents in soils, significant correlations were found among the maximum percentage increase of DTPA-extractable Pb and Cd and the ratio Bc/TOC and metabolic quotient (qCO₂) which may be a result of the important role of organic matter and microbial characteristics in soils on the heavy metal availability.

Water regimes of extensively used grasslands (one cut per year, two cuts per year, no cut, mulching) were determined and compared by drainage lysimeters in 1998-2000. Although the botanical composition and yields of experimental swards were different, there was no statistically significant difference in their water regime (only the soil moisture content of no-cut variant was significantly higher than in other variants). A determinant factor for the water regime of grasslands (GR) is the sum of rainfall over the growing season while the GR water regime is influenced by land use immediately after the cut. Water runoff from the soil profile 0.0-0.60 m (water supply to the groundwater level) was found to be negligible in the growing season, a substantial groundwater recharge occurs in an off-season period and/or at the beginning of growing season. Mulching was not proved to reduce evaporation. The best type of management providing for the economical water regime appears to be a one-cut variant. Relationships between botanical composition and GR water regime are also described.

The monitoring was carried on in the years 1996-2000 in the international IOSDV (Internationale Ökologische Stickstoff Dauer Versuche) field trial running since 1983 in Lukavec, Pelhřimov district. In the given locality, there are low fertility sandy-loamy cambisoils, long-term average annual rainfall 653 mm, average annual temperature 7°C, altitude 620 m. In the field trials there were introduced different organic fertilizations and graduate N-doses. According to the complex diffusion analysis, statistically significant for the yields of winter wheat after potatoes was the impact of N fertilization, years, and double interactions, with the exception of different organic fertilization. The N doses up to 120 kg.ha^-1 after potatoes proved to be optimal from the viewpoint of winter wheat yields and quality. The situation was similar for winter barley. The results of diffusion analysis for individual years were analogical also in straw yields of both cereals. The highest N dose to potatoes (200 kg.ha^-1) resulted in the highest tuber yields, but the starch content was significantly lower. Graduated N doses increased in cereals the numbers of ears per m2, but the mass of 1000 grains mostly decreased. In addition, N content in grain and straw increased with N doses, while pH annually decreased by 0.1 to 0.4. On plots without organic fertilization the N-balance was equilibrated with the annual application of 120 kg N.ha^-1 with straw embedding after cereals at 90 kg N.ha^-1 and on plots with stall dung to potatoes already at 70 kg N.ha^-1. On plots without N fertilization, the balance was passive also in P and K on plots without organic fertilization. A balance surplus was obtained already with the annual application of 15 kg P.ha-1 and 83 kg K.ha^-1 and organic fertilization. With the annual fertilization with 22 kg P.ha^-1 and 83 kg K.ha^-1 and stall dung (30 t.ha^-1) once every three years the P and K content increased annually by 1 to 3 mg.kg^-1 of soil. Maximum levels of crop growing profitability were obtained with those doses of fertilizers with which also an equilibrated balance of nutrients was obtained.

The benefits arising from adoption of information and communication technology by farming businesses are explored, and the prospect of a digital divide appearing in the UK agricultural sector is discussed, drawing on results of research at the University of Plymouth. It is proposed that countries in Central and Eastern Europe will be subject to the same phenomenon, and that the potential disadvantage suffered by non-adopters of this technology will be sufficiently severe to justify both policy intervention and further research.

The aim of this paper is to summarize the results of the EU Phare ACE research project P97-8158-R, "Micro-economic analysis of farm restructuring in Central and Eastern Europe", that tries to fill the gap of theoretical as well as empirical research into the implications of continuing and evolving farm restructuring in CEECs on the efficiency of the agricultural production sector and the development of rural areas by focusing on the economic decisions and perspectives of farm operators, asset owners and rural households. For this purpose, surveys among family farms and farm enterprises were carried out in 2000 in Albania, the Czech Republic and Slovakia.

The article deals with the preparation of the agricultural business structure for accession into the European agrarian structures in the pre-accession period. Main attention is devoted to the preparation of agrarian management and to changes in the macroeconomic area. From the viewpoint of the information mentioned above, the paper includes the explanation of the agrarian functions in the agrarian sector and prediction of the development of business base in the sectors of agriculture, food processing industry and services. The synthetic part deals with the integration and globalization tendencies in the agricultural and food production.

Countries associated in the European Union pay great attention to the development of small and medium-sized enterprises. At the same time, however, the member states are concerned that following the EU enlargement strong migration flows on the part of new members are likely to occur. Therefore, it is in the interests of the member states to learn whether the citizens of candidate countries are internally motivated to run their own businesses and whether suitable conditions have been created, i. e. whether there are any factors negatively affecting the establishment of small enterprises. To this end, an extensive survey was carried out in the Czech Republic aimed at the above mentioned issues and at identifying favourable and unfavourable factors in the process of small enterprise establishment in transition economies, using the Czech Republic as an example.

This four years experimentation work was aimed at research on using various waste organic materials and especially timber bark in cultivation substrates as a substitute of peat. Sixty-four special isolated cultivation beds were established for this purpose, each of 4.8 m³ volume, in which 11 variants of substrates consisting of different proportions of different components in several replications were tested. Standard substrates Horticultural substrate B and RKS I. were used as controls. Another variant was used as a control for growing tests of plants in containers. All tested substrates were enriched with hydroabsorbent TerraCottem. In some variants reserve fertilisers with slow release of nutrients (Silvamix Forte) were applied. For cultivation testing of studied substrates four ornamental tree species (Alnus glutinosa, Fraxinus excelsior, Salix alba, Salix matsudana) were chosen. The best evaluated variants were the ones containing 50 and 75% of bark in combination with sand. The worst was the variant composed of chips and sawdust. Thanks to the use of hydroabsorbents, even the variant containing 100% of sand appeared to be very good. The tested trees had different reactions to the different types of substrates depending on their species requirements. The limiting growth factor for Alnus was the content of water in the substrate. Similarly, the content of available nutrients in the substrate was essential for Fraxinus. The hardwood cuttings of Salix not only rooted into the substrate in a few weeks, but also formed aboveground parts of the required sizes. Obtained data on growth parameters differed according to the diversity of requirements of the different studied species.