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The aim of study was to verify a possibility of adding boron to multi-nutrient soil tests: Mehlich 3, water (1:5) and 0.5M NH₄-acetate extraction. Thirty-six different soils from topsoils of agriculturally farmed field were used for the study. The basic set of 36 soils was doubled when the same soil samples with gypsum addition at an equivalent dose 2 t Ca/ha were used. The closest correspondence between B in soil (n = 72) and B in plant was found out by the NH₄-acetate soil test. This test proved its good universality and independence on a radical intervention in soil chemistry by gypsum treatment. It responded to an increase in B-availability to plants after gypsum treatment of soil. The adjustment of NH₄-acetate boron by the percentage difference between the actual and the desired pH of soil improved the closeness of the correlation. Although the H₂O soil test showed its lower universality, it is assumed to use the H₂O soil test for prediction of B-status in soil when the history of previous fertilisation of the field will be known. The Mehlich 3 soil test did not prove to be suitable for diagnostics of B-status in soil.

This study compares effects of 2,3,5-triiodobenzoic acid (TIBA) and flavonoid quercetine (Q). In spite of the fact that both these compounds are inhibitors of the polar transport of auxin, a number of experiments demonstrated that their properties are different. If the flax seedlings were decapitated and one cotyledon was removed, the axillary bud of the remaining cotyledon grew up more intensively while TIBA (0.5% applied in the form of a lanolin paste on the remaining cotyledon) induced a correlative reversal so that axillars of removed cotyledons grew up more intensively. However, when Q (0.5%) was applied on the remaining cotyledon in the form of a lanolin paste, this inhibition was not significant. In the lamina-deprived petioles of apple trees TIBA accelerated abscission while Q caused an inhibiting effect similar to that of auxin. TIBA applied on epicotyls of pea seedlings inhibited their growth by 35% while Q only by 15%. As far as the release of ethylene by pea seedlings is concerned, both compounds showed promoting effects similar to the effect of auxin.

The effect of sewage sludge application on three soils of different properties (Chernozems - location Suchdol, Luvisols - location Červený Újezd and Cambisols - location Humpolec) was investigated in pot experiment and the accumulation of Zn in above ground biomass of oat as well as availability of Zn released by 0.01 mol/l CaCl₂ was evaluated. Stabilised sewage sludge was obtained from three wastewater factories in Czech Republic. Sewage sludge has been preincubated with addition of limestone and lime (7% of Ca w/w of sludge dry solid) in aerobic and anaerobic conditions and tested in pot experiment. The highest Zn mobility reduction was found at Humpolec soil. Sludge amended by lime and limestone reduced available Zn content in this soil (at sludge III by 86% after limestone and by 71% after lime application). Considerable reduction of Zn in plant showed in Humpolec soil treated by sludge with lime (by 20% compared with soil treated by nonincubated sludge - control) and limestone (by 30% after anaerobic incubation compared to control). The positive incubation and treatment effect was not confirmed in the other soils. Available Zn in Humpolec soil showed the strongest correlation among all soils with total Zn content in plant (at aerobic treatment R² = 0.66 and at anaerobic R² = 0.83).

Barley seed sensitivity to water and anoxia was tested. Standard germination, mean time of germination (MTG), germination in sand wetted by water to 100% water capacity (anoxia) or by hydrogen peroxide (wet conditions without anoxia), germination in 0.75% hydrogen peroxide and laboratory emergence (15 and 20°C) were evaluated. Barley seed responds sensitively to stress conditions during germination. Significant germination decrease was found in abundance of water. Percentage of reduction depends on the variety and on the year of seed production. Extreme values of water sensitivity are in interval 4-90%. At wetted sand by 0.75%, solution of H₂O₂ the germination was significantly less reduced. That means that barley seed is very sensitive to oxygen deficiency above all and is less injured by quick imbibition. Heterogeneity in seed vigour was demonstrated in laboratory emergence tests. Quick test of germination in 0.75% hydrogen peroxide deserves attention for its high correlation coefficient with the seed laboratory emergence. The results significantly demonstrate a higher sensitivity of deteriorated seed to germination in abiotic stresses conditions. Variability in speed of germination is increasing, which unfavourably extends the mean time of germination.

The influence of long-term regular mineral fertilization on the soil environment considering the total sulphur and the sulphur balance in the habitat of the permanent mountain meadow was investigated. The experimental field (set up in 1968) is situated at Czarny Potok (20°8' E, 49°4' N) in the central part of the Polish Carpathian. With completed annual NPK fertilisation 1.8 kg S/ha was introduced into the soil. The highest sulphur amount was found in the 0-10 cm horizon and this value slightly exceeded the content considered as natural. The sulphur content in the sward from Czarny Potok was lower than the mean sulphur content calculated in Poland for grasses (0.21% S). In the case of full NPK fertilisation the amount of removed sulphur ranged from 11.4 to 14.0 kg S/ha. The mean sulphur leaching into the soil profile from surface of 1 ha can be estimated from 1.1 to 3.7 kg S/ha.

The aim of the study was to determine the effect of soil contamination with diesel oil (3, 6, 9, 12 and 24 g/kg soil) on the yield and the content of macroelements in oat and maize cultivated in soil supplemented with nitrogen and sawdust. The correlation between the content of macroelements in the crops and the soil enzymatic activity was also determined. High doses of diesel oil had a definite negative effect on the content of all macroelements in oat, excluding phosphorus. The presence of diesel oil had a favourable effect on the accumulation of most of macroelements in the above-ground parts of maize. Nitrogen application to the soil caused an increase in the content of nitrogen and in the accumulation of calcium and magnesium in the above-ground parts of both crops as well as an increase in sodium content in maize. Sawdust applied to the soil had a considerably lower effect (several to less than 20%) on the content of macroelements in plants. A correlation between the activity of urease and acid and alkaline phosphatase in the soil and the content of macroelements in plants cultivated in diesel oil contaminated soil was observed. This correlation was positive only in the case of alkaline phosphatase activity and phosphorus content in oats.

Partial characterization of iron binding compounds in spinach above ground biomass and differences between binding of Cd, Zn and Fe in spinach biomass were investigated on two soils treated by sewage sludge in model pot experiment. After application of sludge to both soils, Cd and Zn accumulation in spinach biomass was increased in sludge treatments. Total Fe content in biomass showed opposite trend with these treatments and was decreased 2.5-2.7 fold. Results of sequential analysis of spinach biomass showed lower portions of iron in all individual fractions of both sewage sludge treatments compared to control treatments. The largest differences in iron content between control and sludge treatments were determined in ethyl acetate fraction. While majorities of Cd and Zn were found in fractions methanol + H2O and H₂O and methanol + H₂O + HCl, iron content determined in these two fractions was only 7-8% in control treatments and 15-20% in sludge treatments of total iron. In fraction, Fe portion was 87.7-90.7% in treatments without sludge and 76.1-83.5% in sludge treatments in spinach biomass. Results showed tighter iron binding to plant cell membranes in contrast to cadmium and zinc.

The effect of an abiotic stress caused by cadmium on the total flavonoid content in roots, shoots and leaf blades of spring barley variety Kompakt grown in a climate-control room for 28 days was investigated. Total flavonoid content (F) was determined spectrophotometrically with sodium nitrite, Cd content by atomic absorption spectrometry. Treatment of barley plants with Cd (1.10^-6 mol/l) in nutrition solution caused the decrease of F in the all parts of the plant. The relatively highest decrease was found in the roots (from 20.0 to 3.05 g/kg dry matter), lesser decrease in the shoots (from 24.2 to 9.33 g/kg dry matter) and the leaf blades (from 58.3 to 27.3 g/kg dry matter). Statistically significant decrease (at least p < 0.05) of F and increase of Cd contents in all the investigated parts of the plant was found. Statistically significant differences of F and Cd contents among barley roots, shoots, and leaf blades were found.

The influence of mycorrhizal fungi on field pea green mass yield, dry matter yield, grain yield, number of pods per plant, number of grains per pod, average number of plants per m², grain concentration of nitrogen, phosphorus and potassium were studied in the greenhouse during two investigative years. The best results with all parameters were obtained in both investigative years by seed inoculation with the mycorrhizal species G. mossae. The exceptions were mean green mass yield, dry matter yield and the number of grains per pod in the second investigation year (irrigation rate - 240 mm/m²) where better results were achieved by seed inoculation with species G. intraradices. The highest green mass yield obtained by seed inoculation with mycorrhizal species Glomus mossae was 671.45 g/m², dry matter yield 59.40 g/m², grain yield 346.20 g/m² whereas grain nitrogen concentration was 4.08%. Far better results of all yield and quality indicators of this plant compared to non-mychorrized variants were accomplished by mycorrized variants in water lacking conditions.

The research objective was to investigate the influence of different pipe drainage systems on the concentration and quantity of atrazine leached in drainage water, as well as in surface (0-30 cm) and sub-surface (30-60 cm) soil horizons in the production of agricultural crops on drained Gleyic Podzoluvisol. Investigations involved four different variants of drainpipe spacing (15, 20, 25 and 30 m, i.e. four variants in four repetitions). In a particular trial year, the same crop was grown and the same agricultural practices applied in all trial variants. Maize was grown in the first two trial years and wheat in the last year. Soil and water samples were qualitatively and quantitatively analysed for the presence of atrazine by gas chromatography. Atrazine concentrations in drainage water ranged from those within the limits tolerated for drinking water (out of the growing season) up to 458 ng.dm^-3. Maximum quantity of leached atrazine was recorded in 1998 (0.500 g.ha^-1), namely, from atrazine application in May 1997 to March 1998 incl., 0.630 g.ha^-1 or 0.052% of the initially added quantity was leached. Maximum atrazine concentration in the surface soil layer was recorded in traces or it was not recorded at all (0.013 mg.kg^-1), whereas no atrazine was recorded in the subsurface layer during the trial period. Analysis of variance produced no statistically significant difference in the atrazine concentration and leaching in drainage water and in the surface soil layer between different variants of pipe drainpipe spacing.

Changes in the zinc content in the meadow sward were studied in a long-term fertiliser experiment set up on a mountain meadow (20°54'E, 49°24'N) in 1968. The experiment is localized at 720 meters above sea level on the soil which belongs to Dystric Cambisols and comprises 8 fertiliser treatments in two series: 0Ca and + Ca (Table 1). In the course of the experiment the Zn content in the sward decreased and the time factor was of greater consequence than fertilization, P content in the sward or soil and acidification. In mountain meadow communities shaped by a long-term (over 30 years) NPK treatment and at yields between 6.7 and 7.1 t/ha the annual quantity of absorbed Zn ranged between 233 and 256 g Zn/ha dry weight. During the experimental period the biggest amount of Zn removed with the sward yield exceeded 500 g Zn/ha annually. In the limed series at slightly bigger yields the quantity of Zn removed with the yield was over 10% lower in objects receiving NPK fertilization than on the same treatments in the unlimed series. Liming is able to reduce soil Zn abundance.

The effect of addition of treated sewage sludge on the accumulation of Zn in plants was tested in pot experiment. The additions of eight months preincubated sewage sludge at temperature of 20°C under aerobic and anaerobic conditions with addition of peat and straw were tested. Two different combinations were designed: first consisted of 50% sludge + 35% peat and 15% straw, and second was made of 50% sludge + 5% peat and 45% straw (expressed as dry matter). Three different soils Chernozems, Luvisols, and Fluvisols and three sludges were tested in the experiment. Oat (cv. Pan) was planted as experimental crop. All treatments were fertilized by NPK. Green biomass of oat was harvested and analyzed. At treatments with addition of both composted sludges pH dropped down causing higher mobility of Zn in sewage sludge. Oat grown in these treatments contained higher amount of Zn compared to untreated soils. The application of anaerobically treated sludge led to increased Zn content in biomass compared to aerobically incubated one. Predominant effect on Zn accumulation in plants was determined by tested soil. The highest content was determined in plants grown on Fluvisols. The biomass yield was more affected by source of sewage sludge than by the soil type used. Treatments amended by anaerobically incubated sludge showed tendency to higher biomass production due to their higher content of nitrogen and carbon.

Four conservation methods were compared on grassland unused for 30 years: 1. control (unused grassland); 2. one cut, herbage mass was spread for mulch; 3. one cut, herbage mass was removed; 4. two cuts, herbage mass were removed. Experiments were carried out during 1996-2000 at the Kaltinenai Research Station of the Lithuanian Institute of Agriculture in a hilly region of the Zemaiciai Uplands of West Lithuania, on a hilltop and hill slope. During the experimental period an increase in the number of shoots of each botanical group (grasses, legumes and forbs) were identified in all treatments. The highest increase in the total number of grass shoots was characteristic of the controlled treatment on both parts of the hill. At the end of the conservation period, 38 herb species were identified in the trial. Treatments 1 and 2 were richer in floristic diversity (27-33 species) compared with treatments 3 and 4 (20-25 species). The treatments on the hill slope had a more diverse species composition than those on the hilltop. During the grassland conservation period the content of legumes in the herbage mass increased from 0 to 27.7% in the swards where cut herbage was removed.

We evaluated the need for low temperatures (vernalization) and the photoperiodic reaction of three collections of winter oats (1. Pedarn, Maris Quest, Peniarth; 2. Gerald, Solva, Kymon, Pendragon; 3. Pewi, Silwi, Wiskas) in a comparison with spring oats varieties. All three collections of varieties showed little need for low temperatures, mostly as few as 10-20 days, which does not represent an obligatory need; this influence is only quantitative and constitutes no precondition for a passage of plants into the generative stage. Only in the case of the Maris Quest variety, the need for vernalization approached 30 days. As compared with the reaction of winter barley varieties that had and in some cases still have worse overwintering in the Czech Republic, the length of vernalization is equal. In the photoperiodic experiment, the reaction to a short autumn day turned out to be the critical condition for a possibility of autumn sowing and overwintering; in the case of these varieties, a short day inhibits the development until arrival of winter. We evaluated this reaction according to the length of the induction period. This period was only 10-15 days in the case of the spring oats Český žlutý, 30 days in the case of winter oats Maris Quest, 25 days for Pedarn, 20 days for Peniarth and 21 days for Pendra-gon; the induction period was 14-21 days in the case of varieties Gerald, Kymon and Solva. When compared with figures for winter barley, it had the longer photoperiodic induction period. The evaluated varieties of winter oats do not reach such a degree of a reaction to a short day, which manifests itself in their lower frosthardiness than that of winter barley. We verified that in provoking tests for frosthardiness, and also by lower critical values of temperatures for dying out of 50% of plants, the so-called LT 50.

In the paper yield of dry matter and some morphological features of four fast growing willow coppice genotypes harvested in one, two, three and four years harvesting cycles are presented. In the experiment an average yield amounted to 16.79 t/ha/year. The highest yield was recorded for Salix viminalis × S. viminalis lanceolata (22.89 t/ha/year). Genotype Salix triandra gave a yield lower by factor 3 compared to Salix viminalis × S. viminalis lanceolata. For the following genotypes: Salix viminalis × S. viminalis lanceolata, Salix viminalis var. gigantea and Salix viminalis var. regalis it was found the yield increased as harvesting cycle increased from one to four years while the opposite was found for genotype Salix triandra. It can indicate that Salix triandra is not suitable for intensive growing on arable lands, especially in two, three or four years harvest cycles. Mean plant height amounted to 4.63 m and stem diameter 20.48 mm. The tallest plants (769 cm) with the thickest stem (diameter of 37.43 mm) were found for genotype Salix viminalis × S. viminalis lanceolata harvested quadrennially. At harvest water content amounted to 49.87% and the highest value was found for the shortest harvesting annually.

The set of 102 samples of agricultural soils was taken for the study of the load of agricultural soils with polychlorinated dibenzo-p-dioxins and dibenzofuranes (PCDDs/Fs). The background value of PCDDs/Fs in agricultural soils of theCzech Republicwas determined. The soils with different sources of the load of PCDDs/Fs were compared. It was concluded that fluvisols in fluvial zones and soils with long-term sludge application are soils with the highest contents of PCDDs/Fs. The soils affected by imission outputs show a lower intensity of the load with PCDDs/Fs that is characterised by higher content of toxic congeners.

The lack of recombination in some genomic regions represents a serious obstacle in mapping studies. In this review, we describe methods that are currently used to overcome this problem. Main attention is given to the comparison of methods that are based on the principle of radiation hybrid mapping. We also discuss a strategy called HAPPY mapping (mapping based on the analysis of approximately HAPloid DNA samples using the PolYmerase chain reaction). In addition to reviewing the methods used by other authors, we also summarize our experience with deletion mapping of Y-chromosome in dioecious model plant species (Silene latifolia).

Field experiments were carried out to study effects of zinc application on quality traits of barley in 1994-1996. The treatments were applied as 0 and 23 kg/ha of zinc sulphate and incorporated into soil before sowing. The experimental design was split plot with four replications. Barley genotypes responded differently to zinc application in relation to thousand grains weight, protein content and starch content. A significant increase was determined for thousand grain weight in cultivars Tokak 157/37 and Cumhuriyet 50, for protein content in Orza, Bülbül 89 and Anadolu 86, for starch content in Karatay 94 and Cumhuriyet 50, while a significant decrease has been found for thousand grain weight in Karatay 94 and Obruk 86 and for protein content in Karatay 94, Cumhuriyet 50 and Tarm 92. When feeding and malting quality are considered together, Karatay 94 and Cumhuriyet 50 are the most suitable cultivars for growing in zinc-applied soils of semi arid areas.

This review is a short introduction to phylogenetic analysis. Phylogenetic analysis allows comprehensive understanding of the origin and evolution of species. Generally, it is possible to construct the phylogenetic trees according to different features and characters (e.g. morphological and anatomical characters, RAPD patterns, FISH patterns, sequences of DNA/RNA and amino acid sequences). The DNA sequences are preferable for phylogenetic analyses of closely related species. On the other hand, the amino acid sequences are used for phylogenetic analyses of more distant relationships. The sequences can be analysed using many computer programs. The methods most often used for phylogenetic analyses are neighbor-joining (NJ), maximum parsimony (MP), maximum likelihood (ML) and Bayesian inference.

The stability of plant nuclear genome is a necessary condition for the faithful transmission of genetic information through cell lineages. When DNA damage occurs due to various impairments, cells start a number of repair processes including ligation of broken chromosomes. As a result, dicentric chromosomes can be formed. Dicentrics are easily detectable as anaphase bridges during following mitosis. Using Arabidopsis as a model plant, we developed a sensitive cytogenetic assay to identify specific chromosomal rearrangements. Here we show Arabidopsis tert^-/- and atm^-/- mutants and their chromosome rearrangements and fusions analysed by fluorescence in situ hybridization (FISH). The method is based on successive rounds of FISH with chromosome-specific probes and the comparison of resulting FISH images.

The skin colour of 21 varieties was assessed on a molecular level. Four varieties had yellow skin colour with the genotype constitution a¹a¹, a¹a² or a²a². Seventeen varieties had dominant red colour. Homozygous A¹A¹ constitution was present in 7 varieties, and heterozygous constitution A¹a¹ or A¹a² was found in the rest of the assessed varieties. The S-alleles controlled the incompatibility system of the pistil. Their detection is possible by means of the PCR method on the basis of allele specific primers. Six S-alleles (S1, S2, S3, S5, S7 and S9) were studied in the same collection of 21 diploid Czech varieties. This paper brings new findings on S-allele characterization, because the Czech varieties have not yet been studied on a molecular level. Both types of S-allele were found in 12 varieties. Only one type of S-allele was described in 9 varieties. Simultaneously, the presence of the Vf gene was screened in the collection of 21 Czech apple varieties. Ten varieties with a field resistance against the scab had a heterozygous constitution of the Vf gene. All 11 susceptible varieties were recessive homozygous vfvf.

An interrelationship between introduced and indigenous rhizobia focused on their competitiveness in nodulation was evaluated in a soil pot experiment. Clover seeds were inoculated by six different gradual concentrations of inoculum of two effective Rhizobium leguminosarum bv. trifolii isolates (inoculation strains 1/2 and 14/2). At the beginning of flowering, clover plants were removed from the pots, and nodules from each pot representing different degrees of inoculum level were taken for reisolate cultivation. The PCR technique was used for the identification of rhizobial reisolates, random amplified polymorphic DNA product patterns were acquired and analysed. Nodule occupation by inoculation strains or indigenous Rhizobium leguminosarum bv. trifolii strains was assessed by comparing the number of nodules formed by inoculation or indigenous strains and inoculation strains competitiveness was calculated. Nodule occupancy by the inoculation strain 1/2 increased sharply with the increase in inoculum dose, whereas in inoculation strain 14/2 more nodules were formed gradually starting from low inoculum level. Competitiveness of inoculation strain 1/2 was calculated as low and was documented by an absence of nodule occupancy in four inoculation levels. On the other hand, competitiveness of the inoculation strain 14/2 was considerably higher, and even in low inoculum dose this strain was more competitive than native rhizobia. Although both the inoculation strains 1/2 and 14/2 were found highly efficient in nitrogen fixation, only the strain 14/2 was able to manifest this characteristic due to the higher competitiveness when applied in lower doses.

The results of three-year trials (1999 to 2001) conducted with six winter wheat varieties in which was investigated the effect of sites, years and varieties on the final grain yield and technological quality showed statistically significant differences (LSD, 95%) among sites in grain yield and these parameters of quality: test volume mass, wet gluten content, sedimentation test, protein content, falling number and flour water absorption capacity. As to the quality, the Žatec site showed itself as generally most suitable, and the Jaroměřice site as the least suitable one. Climate conditions showed a statistically significant effect (LSD, 95%) on grain yield and all quality parameters, beside the percentage of complete grains and swelling capacity of gluten and falling number, which were insignificant. The most favourable weather conditions, a lot of precipitation and high temperature in the course of ripening from three years were proved in the year 2000. Among the varieties were statistically significant differences (LSD, 95%) in grain yield and these parameters of quality: test volume mass, thousand grain weight, ash content, percentage of complete grains, sedimentation test, protein content, reologic properties of dough and baking tests. From the six varieties the best profits were shown from variety Sulamit (loaf volume 595 ml/100 g of flour), the worst was Semper (loaf volume 543 ml/100 g of flour) and Vlasta (loaf volume 532 ml/100 g of flour). The best grain yield was in 2001 (average of sites 8.84 t/ha) and the variety Semper had the highest grain yield of 9.17 t/ha, that is higher at 13.41% compared with Sulamit (7.94 t/ha).

In our work, we focus on the evolutionary studies of sex chromosomes. As model organisms we use several species of the plant genus Silene. An important part of our research is represented by genetic mapping based on the assays of DNA length or sequence polymorphisms. Apart from the other methods we also use the dCAPS method, which is very useful for detection of the sequence polymorphisms (SNPs). This method is unique as it is able to detect SNPs that are not situated in any restriction site; a fundamental principle of this method is usage of primer designed with one or two mismatches that bring into the target sequence the mutation in vicinity of SNP. Using this method, we found out some improvements that can make analyses more cost-effective.

Ditylenchus dipsaci, the stem nematode, is a migratory endoparasite of over 500 species of angiosperms. The main method of D. dipsaci control is crop rotation, but the presence of morphologically indistinguishable host races with different host preferences makes rotation generally ineffective. Therefore, a sensitive, rapid, reliable, as well as cost effective technique is needed for identification of D. dipsaci in biological samples. This study describes the development of species-specific pairs of PCR oligonucleotides for detection and identification of the D. dipsaci stem nematode in various plant hosts. Designed DIT-2 primer pair specifically amplified a fragment of 325 bp, while DIT-5 primer pair always produced a fragment of 245 bp in all D. dipsaci isolates. Two developed SCAR primer pairs were further tested using template DNA extracted from a collection of twelve healthy plant hosts; no amplification was however observed. The developed PCR protocol has proved to be quite sensitive and able to specifically detect D. dipsaci in artificially infested plant tissues.

Zinc distribution in the main soil fractions and zinc accumulation in potatoes, maize, wheat and barley after different soil treatments (basic sludge rate, triple sludge rate, NPK, NPK + inorganic Zn) were investigated in a field experiment conducted at five localities of the Czech Republic (Červený Újezd, Hněvčeves, Humpolec, Lukavec, Suchdol) with different soil and climatic conditions. Three soil types were investigated in the experiment: clay-loamy Chernozems, loamy Luvisols, clay-loamy Luvisols and two loamy Cambisols. Sequential analyses provided an overview of soil Zn distribution in the following fractions: exchangeable, Fe-Mn oxide, organic and residual ones. The sludge and inorganic Zn addition supported Zn mobility growth and higher Zn retention in Fe-Mn oxides in all tested soils. The influence of the above-mentioned treatments on higher Zn association with soil organic compounds was not explicitly found. Potatoes, wheat and barley accumulated more Zn after its addition into the soils by sludge and inorganic salt. By contrast, Zn content in maize decreased with higher input of Zn into the soil. The highest Zn concentrations were usually observed in plants grown on both Cambisols.

This paper presents the results of a three-year research on the effect of perforated polyethylene foil and polypropylene fibre covering at various lengths of plant cover period (2 and 3 weeks after plant emergence) on the assimilation leaf area of early potato cultivars. In the case of plant covering for 2 weeks after emergence the assimilation leaf area and leaf area index (LAI) at the moment of cover removal were on average 2 times higher than in the cultivation without covering; at the 3-week period of plant covering they were almost 1.7 times higher. A higher favourable effect of covering was obtained in the year with the lowest air temperature in May. The use of the covers at that time increased the assimilation leaf area and LAI 2.5 times and 3 times, respectively. The research showed no significant effect of the type of cover used on the assimilation leaf area and LAI; however, the specific leaf area (SLA) was higher with the use of polypropylene fibre.

Chlorophyll a fluorescence measurements were carried out on two barley (Hordeum vulgare L.) cultivars Arabi Abiad and Arabi Aswad at 8 and 14 days after emergence to identify their early tolerance mechanism for heavy metals (25 and 50μM of cadmium and lead). Transient fluorescence curves (OJIP curves) and energy flux models showed different specific reactions of photosystem II (PSII) of each cultivar to each type of stress. After 7 days of lead stress application plants of cv. A. Aswad showed weaker I and P peaks on the OJIP curve than control plants, and the appearance of a new K step; parameters of phenomenological energy fluxes for cv. A. Abiad were similar to those for control plants and only some silent reaction centers appeared. Generally, parameters of energy fluxes within PSII were directly shifted shortly (24 h) after the application of both heavy metals, especially in the case of plants grown under cadmium treatment. This suggests that these parameters could be good indicators for monitoring of these two pollutants in the environment at early stages of plant development.

To answer many questions of evolutionary developmental biology, it is necessary to identify genes which could be responsible for the studied traits. In this review, I have summarised the methods that are currently used to identify these genes. Mainly the PCR-based methods of gene cloning are discussed here, with the special attention given to the comparison of primer design strategies and PCR amplification strategies. In addition to the review of methods used by other authors, an overview of our experience with PCR-based gene cloning in dioecious model plant species Silene latifolia is included.

A simple method for identification and characterization of telomere-binding proteins is described in this article. After Sodium Dodecyl Sulphate-Polyacrylamide gel electrophoresis (SDS-PAGE), proteins are eluted, renatured and used for retardation analysis with labelled oligonucleotides corresponding to human and plant of telomeric sequences. We show here that this method is efficient to recover sequence-specific DNA-binding abilities of putative telomere-binding proteins.