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The objective of this study was to determine the effect of foliar urea applications on quality, growth, mineral content and yield of broccoli under field conditions in 2003, 2004 and 2005. Broccoli cultivars AG 3317 and AG 3324 were treated with foliar urea applications at different concentrations (0.0, 0.4, 0.8 and 1.0%). Foliar applications of urea, especially 0.8 and 1.0% resulted in larger heads, weightier heads and plants as well as higher plants. Conversely, the greatest head and leaf dry matter contents were obtained with no fertilizer-nitrogen application. SPAD chlorophyll readings that were measured in the third year increased with elevated urea concentrations. In regard to the nutrient content, it can be interfered that soil nitrogen fertilization and foliar urea applications increased the content of almost all nutrients in leaves and heads of both broccoli cultivars in three experiment years. Generally, the greatest values were obtained from 1.0% urea application for both cultivars. It results from the study that for optimum yields 0.61 and 0.96% concentrations of urea sprays could be successfully used to obtain better growth and yield in broccoli cultivars AG 3317 and AG 3324, respectively.

Limited information is available regarding the source-sink alterations on soybean yield under whole plant light enriched conditions. The differential responses of yield components for two old and two new cultivars were investigated. The yield sensitivity of the old cultivars to the changes in source strength and light enriched conditions was much greater than that of the two new cultivars. The yield of the new cultivars was more likely sink-limited, and source-limited for the old cultivars. The increased yield by light enrichment was in part due to an increased branch contribution. Pod number per plant was more responsive than seed number per pod. The reduction in pod number by source-sink manipulation was more severe in the old cultivars. Light enrichment increased pod number in the two old cultivars but not in the two new cultivars. Seed size was responsive to changes in the source-sink ratio and changes in the environment. Both pod number or seed size may be increased or decreased if environmental conditions for seed filling are altered.

The effect of three seedling treatments: T₀, normal germination; T₁, cotyledons removed; T₂, cotyledons removed 5 days earlier than in T₁; and two phosphorus levels (P₀ and P₃₀) on nodulation and nodule function in soybean [Glycine max (L.) Merr.] were investigated in nutrient solution culture. The number of nodules formed at P₀ was in the order T₂ > T₀ > T₁, but it was T₀ > T₂ > T₁ at P₃₀. Nodule dry weight per plant had the same tendency as the nodule number. Nodule size (dry weight per nodule) in seedlings ranged from 0.601 to 1.089 mg in the order T₀ > T₁ > T₂, regardless of P level. For example, nodule size in T₀ was larger by 86% and 52% than T₂ at P₀ and P₃₀, respectively. Furthermore, regardless of P level, a specific acetylene reduction activity (ARA, µM C₂H₄/h/g nodule) increased with P content in seedlings, but no significant difference was found (P < 0.05). Leghemoglobin (Lb) content was not significantly affected by P level; however, seedlings (T₀ and T₁) significantly affected the Lb content per unit plant biomass (P < 0.05). All these results suggest that seedling P content plays a key role in nodulation and nodule function of soybean.

An endophytic fungus of soyabean (Glycine max) roots, Fusarium oxysporum, was used to study its activity under heavy metals (Cd²⁺, Mn²⁺ and Zn²⁺) stress and the role of rock phosphate (RP) in alleviation of the stress. F. oxysporum growth, amino acids and protein were increased by increasing RP concentration (1-6 g/l) after 8 and 14 days. Heavy metals (HM) have a stressing effect on F. oxysporum - a significant decrease of amino acids, protein and accumulation of sugar at 1mM/l follows a descending order of Cd²⁺ > Mn²⁺ > Zn²⁺. RP is altering the stressing effects of metal on F. oxysporum by a significant growth improvement at 3 and 6 g/l RP, increase of amino acids, protein and decrease of sugar. The solubilization of RP increased under HM application, which may be attributed to an increase of the adsorption of HM by increasing RP concentration. RP has the highest adsorption affinity for Cd²⁺ (81%) followed by Zn²⁺ (71%) and Mn²⁺(55%).

In several cases ethylenediaminetetraacetic acid (EDTA) proved to be an efficient mobilising amendment during chemically enhanced phytoextraction of heavy metals. The presence of Fe-(hydr)oxides and their dissolution after the addition of EDTA can limit the phytoextraction of the targeted heavy metals due to the high stability of the formed Fe(III)EDTA complexes. This study has focused on the influence of Fe- and Mn-oxides and hydroxides dissolution on heavy metal uptake by Zea mays in a two-year EDTA-enhanced phytoextraction process. Incubation experiments and speciation modelling proved the increased concentrations of Mn and Fe through the dissolution of Mn-and Fe-(hydr)oxides. Furthermore, increased Fe and Mn accumulation was observed in maize plants after the second year of the phytoextraction process. Therefore, the presence of Mn- and especially Fe-(hydr)oxides proved to be a limiting factor during EDTA-enhanced phytoextraction of heavy metals from contaminated soils.

The risk of Pb contaminated soil after treatment with different remediation techniques was assessed. Soil vitrification (microwaves) reduced Pb orally available from the stomach and intestinal phase measured by a physiologically based extraction test. Solidification of Pb (Slovakite) did not reduce the concentration of orally available Pb and increased the Pb uptake by Thlaspi goesingens for 2-times compared to plants grown on the original soil. Soil extraction with 40 mmol/kg EDTA removed 57.6% of Pb. However, the concentration of orally available Pb and Pb uptake by T. goesingens increased. The concentration of mobile soil Pb also increased for 14-times measured by a toxicity characteristic leaching procedure. Soil leaching with 10 mmol/kg biodegradable chelator [S,S] ethylenediamine disuccinate and using a horizontal permeable reactive barrier for Pb accumulation from the washing solution removed 17.8% of Pb, but increased Pb uptake by T. goesingens by 3-times and slightly increased the concentration of Pb in the intestinal phase. Leaching did not significantly effects Pb availability from the stomach phase or Pb mobility.

The influence of N-S fertilizers on the copper content in the inter oilseed rape plants was studied in field experiments. The evaluation involved two treatments of a single rate for the first spring fertilizer application with 100 kg N/ha in the AN treatment (nitrochalk) and 100 kg N/ha + 50 kg S/ha in the ANS treatment (ammonium nitrate and ammonium sulphate). A positive influence of the ANS fertilizer on the copper contents in different parts of plants was determined. The highest Cu concentrations were determined in the leaves and inflorescences, the lowest ones occurred in the stem. The concentration of Cu ranged within the interval of 1.56-8.75 mg Cu/kg of dry matter depending on the growth period and the part of the plant. No differences in copper content were determined in the seeds of individual treatment. The highest uptake in the above-ground parts of the plants was recorded in the green pod period and amounted to 57.4 g Cu/ha for the ANS treatment.

The basic concept of malt barley production is to reach a dilution effect of nitrogen accumulated by grains at maturity. A three-year study was undertaken to establish time courses of nitrogen (N) and sulphur (S) in leaves as the prerequisite tool for total grain yield prognosis. Sulphur application at the lowest rate of 25 kg/ha significantly increased yields of grain in 2001 and 2003. The time course of N and S concentrations in leaves over the growing season showed declining trends for N and variable for S. At mid tillering (BBA-25) both N and S, but at BBA-31 only N concentrations significantly responded to S rates, and in turn affected patterns of N concentration in barley organs up to maturity. Sulphur concentrations and N:S ratios were useful tools to make reliable prognosis of total grain yield of barley at BBA-31 as indicated by the obtained regression equations. The threshold values for N and S in leaves in order to achieve the maximum total grain yield are 0.4% for S and 8.0 for the N:S ratio as presented by the graphical procedure.

A pot greenhouse experiment was performed to determine the effect of contamination with nickel interacting with other heavy metals on the microbiological properties of soil. The study was conducted on samples of soils classified under natural conditions as typical Eutric Cambisol developed from heavy loamy sand and typical Eutric Cambisol developed from light silty loam. Soil material was contaminated with nickel in the amount of 50 and 200 mg Ni²⁺/kg. The treatments with 200 mg Ni²⁺/kg were additionally contaminated with other heavy metals (Zn²⁺, Cu²⁺, Pb²⁺, Cd²⁺, Cr⁶⁺), in the amount of 50 mg/kg soil. The following treatments, in which the soil was contaminated with heavy metals applied alone or in combinations, were compared in the study: Ni, Zn, Cu, Pb, Cd, Cr, NiZn, NiCu, NiPb, NiCd, NiCr, NiZnCu, NiZnPb, NiZnCd, NiZnCr, NiZnCuPb, NiZnCuCd, NiZnCuCr, NiZnCuPbCd, NiZnCuPbCr, NiZnCuPbCdCr. The experiment was carried out in four replications. A microbiological analysis was performed on days 28 and 56. The tested crop was oat. It was found that the impact of particular heavy metals on microbiological properties of soils depended on their type, interactions between nickel and zinc, copper, lead, cadmium and chromium (VI), date of analysis and soil species. Soil contamination with heavy metals reduced the population size of Azotobacter spp. The counts of other microbial groups, i.e. copiotrophic bacteria, spore-forming copiotrophic bacteria, oligotrophic bacteria, spore-forming oligotrophic bacteria, ammonifying bacteria, nitrogen immobilizing bacteria, cellulose-decomposing bacteria, Arthrobacter spp., Pseudomonas spp., actinomyces and fungi, showed varied susceptibility to heavy metals.

Soils were sampled from the plots with four variants of fertilisation: Nil - without fertilisation, NPK - mineral fertilisation, FYM - farmyard manure, FYM + NPK - farmyard manure with mineral fertilisation, and two variants of crop rotation: field IV - classical 9-year crop rotation, field B - 2-year rotation of alternative growing. Determination of urease, CFU of Azotobacter spp. and potential nitrogenase activity was conducted during the period 1999-2004. The urease activity was positively affected by manure fertilisation (FYM) and by the combination of FYM + NPK. The statistically significantly highest counts of Azotobacter spp. and the highest nitrogenase activity were determined on field B in variants FYM and FYM + NPK. The results show that there was a higher amount of accessible nitrogen present on field IV than on field B. This might explain the lower counts of Azotobacter spp. and therefore the lower nitrogenase activity. According to our results, activity of urease, CFU of Azotobacter spp. and potential nitrogenase activity are very closely connected with N inputs.

The use of plants to remove heavy metals from soil (phytoremediation) is expanding due to its cost-effectiveness as compared to conventional methods and it has revealed a great potential. Since contaminants such as Pb or Cd have a limited bioavailability in the soil, methods to facilitate their transport to the shoots and roots of plants are required for successful phytoremediation. The objective of this study was to investigate the effects of addition of different rates (0, 3, 6 and 12 mmol/kg) of ethylene diaminetetraacetate (EDTA) on heavy metal availability in soils contaminated with 50 mg/kg Cd (CdCl₂), 50 mg/kg Cu (CuSO₄), 50 mg/kg Pb [Pb(NO₃)₂] and 50 mg/kg Zn (ZnSO₄), and on the capacity of canola (Brassica napus L.) and Indian mustard (Brassica junceaL.) plants to uptake Cu, Cd, Pb and Zn in a growth chamber. Results indicated that EDTA application increased heavy metal availability and uptake by plants. Significant differences were obtained in both species and plant parts. As for plant species tested, canola was more effective in the uptake of Cu, Cd, Pb and Zn. Root heavy metal uptake of both species was higher than shoot heavy metal uptake.

Current sequencing projects are often based on random sequencing of genomic libraries followed by contig assembly by means of bioinformatics tools. This approach is convenient for whole genome sequencing projects. Chromosome walking described here is suitable for mapping and sequencing of short genomic regions in species where whole genome sequencing is not possible or for cloning gene from its closest known marker. This method is based on searching for overlapping BAC clones specific for the genomic region of interest.

Pot experiments were conducted to determine the best time for application of (ethylenediaminetetraacetic acid) EDTA and sheep manure extract (SME) in phytoremediation of a contaminated soil by Helianthus annuus. The plant was grown in a mine calcareous soil treated with increasing concentrations of EDTA or SME in 30 and 10 days before sowing (T1 and T2) and 10 and 30 days after sowing (T3 and T4). The best time for EDTA application was T4. The EDTA application before seed germination significantly reduced sunflower seedling emergence and dry weight. Soil available Pb and lead concentrations in plant organs increased with EDTA concentration but the actual amount of phytoextracted Pb decreased at high EDTA concentrations significantly, due to severe growth depression. SME application after sowing can increase plant dry weight and Pb concentration in the soil solution, enhancing the accumulated metal concentrations in shoots and roots. However the results showed that the most efficient treatments for Pb phytoextraction by sunflower are applications of 0.5 and 2 g EDTA/kg soil at T3 and T4, respectively.

We conducted a pot experiment to evaluate the Cd and Zn accumulation in leaves and roots of Salix smithiana (BOKU-03DE-001) and S. caprea (BOKU-01AT-004) clones grown on a metal-contaminated soil as affected by native microbes extracted from the same experimental soil, and the fungus Cadophora finlandica. Plant biomass production of S. smithiana was decreased in all the treatments compared to the sterilized control. In contrast, S. caprea grew best on the non-sterilized soil. Similar effects were observed for plant Zn and Cd contents. Microbial treatments affected metal accumulation differently in the two Salix species. The effects of the microbial treatments on biomass and metal content of leaves were not related to the degree of mycorrhization. A comparison with literature data suggests that the plant response to microbial inoculation in terms of metal accumulation may depend on the plant-internal metal concentration. Our findings also illustrate a difficulty of successful rhizosphere management using metal-tolerant microbial isolates to further enhance the phytoextraction process.

Malt barley production requires a technology increasing nitrogen use efficiency, because of a high sensitivity of barley total grain yield and quality parameters to external growth factors. In the conducted study an effect of two P fertilizers on the background of N application on total and technological grain yields were studied. The highest total grain yield was harvested on plots fertilized with 60 kg N/ha, irrespective of the P fertilizer type. However, the technological grain yield showed a high year-to-year variability; the highest was recorded in 2001 on the plot fertilized with 60 kg N/ha and the P-PAPR fertilizer. The N and S concentrations and N:S ratios in immature grains at harvest were used to evaluate both yield types. Nitrogen concentration in the final total yield allowed making yields prognosis with the highest probability. The maximum yields of technological malt barley were attainable provided that total S concentration in immature grains at harvest was above 0.23% and the N:S ratio was narrower than 8.0.

Seeds are the primary sinks for photosynthates during reproductive growth. Variation in light intercepted during and after seed initiation has been found a major environmental determinant of soybean [Glycine max(L.) Merrill] seed size. We investigated the influence of light enrichment and shading on seed growth rate, effective filling, cotyledon cell number, cell volume and endogenousABA concentrations of cotyledons/testas during seed filling of soybean. Evans, an indeterminate Group 0 soybean, was subjected to light reduction and enrichment treatments from the beginning of pod formation until final harvest for two years inMassachusetts. Higher rates of seed growth, greater seed dry weight, and higher cotyledon cell number were all observed with light enrichment. There was a reduction in seed growth rate and cotyledon cell number, along with a significant lowering of endogenousABA levels in testa and cotyledon with shade. The level ofABAin cotyledon during seed development was significantly correlated with seed growth rates only under shade treatments. Both the growth rates and seed filling duration were influenced by variation in light interception by the soybean canopy. The effects of varying light treatment on seed size, within one genotype, were most likely due to the differences in seed growth rate and cotyledon cell number.

The aim of the present paper was to determine the impact of gypsum treatment of soils on initial growth and nutrient uptake by spring barley. Topsoil from 36 different farmed fields was used for the research. Two variants were established for each soil: control - without gypsum application, and response variant - with the application of 3.3 ppm CaSO₄.2 H₂O. Barley was grown on these soils for 21 days in a plant growth chamber under controlled conditions of cultivation. Concentrations of nutrients (N, NO₃^-, P, S, K, Mg, Ca, Na, Fe, Mn, Zn, Cu, B and Mo) were determined in the yield of barley shoot biomass. Paired t-test was used for the evaluation of results. After the gypsum treatment the yield of barley shoot biomass was significantly higher (by 15% on average) and nitrogen utilisation was better on all soils. The concentration of sulphur increased five times on average and Ca concentration increased by 22%. Significant increases were measured in Mg, Mn and Cu. Insignificant differences were recorded in K, Na, Fe and Zn. The uptake of anion nutrients (P, B and Mo) was influenced significantly. The concentration of P and Mo decreased on average by 28% and 31%, respectively. B concentration was higher by 10% on average.

The mechanism of cisplatin effect has been well examined in in vitro models of malignant cell lines, but has never been studied on plant cell lines. When plant cell suspension culture of Nicotiana tabacum BY-2 was treated with cisplatin a decrease of viability with its increasing concentration was observed as well as the mitotic index. The structure of nuclei has also been changed in dependence on cisplatin concentration.

This paper presents the results of a three-year research on the effect of perforated polyethylene foil and polypropylene fibre covers on the growth of early potato cultivars at various lengths of plant covering period (2 and 3 weeks after plant emergence). Plants grown under covers were higher, produced higher mass of above-ground parts, and were characterised by a smaller value of leaf weight ratio (LWR) and leaf area ratio (LAR) compared with the cultivation without covering. In the case of plant covering for 2 weeks after emergence the mass of leaves at the time of cover removal was on average almost 2 times higher and the mass of stems over 2.5 times higher than in the cultivation without covering; the values of LWR and LAR were however smaller by 0.094 and 0.137 m

Cadmium mobility in sewage sludge amended by four types of ameliorative materials (lime, limestone, bentonite and zeolite) incubated under aerobic and anaerobic conditions for eight months was studied in the experiment. The most statistically significant decrease of available Cd extracted by 0.01 mol/l CaCl₂ was recorded in sludge between second and fourth months of incubation. As most effective stabilizers were found limestone and bentonite added into the sludge incubated under aerobic and anaerobic conditions respectively. The presence of air reduced Cd mobility in individual sludges more than lack of air. Cadmium was separated by sequential extraction into five fractions as water soluble, exchangeable, bound with Fe and Mn oxides, organically bound, and residual fraction. Sequential analysis showed decrease of Cd in exchangeable and oxide fractions in sludge treated by lime and limestone at the end of aerobic incubation. Cadmium was found in water soluble and exchangeable fractions in small portion, even so its content in these fractions was higher than determined in slighter 0.01 mol/l CaCl₂ solution.

Soil organic carbon (SOC) is the most often reported attribute and is chosen as the most important indicator of soil quality and agricultural sustainability. In this review, we summarized how cultivation, crop rotation, residue and tillage management, fertilization and monoculture affect soil quality, soil organic matter (SOM) and carbon transformation. The results confirm that SOM is not only a source of carbon but also a sink for carbon sequestration. Cultivation and tillage can reduce soil SOC content and lead to soil deterioration. Tillage practices have a major effect on distribution of C and N, and the rates of organic matter decomposition and N mineralization. Proper adoption of crop rotation can increase or maintain the quantity and quality of soil organic matter, and improve soil chemical and physical properties. Adequate application of fertilizers combined with farmyard manure could increase soil nutrients, and SOC content. Manure or crop residue alone may not be adequate to maintain SOC levels. Crop types influence SOC and soil function in continuous monoculture systems. SOC can be best preserved by rotation with reduced tillage frequency and with additions of chemical fertilizers and manure. Knowledge and assessment of changes (positive or negative) in SOC status with time is still needed to evaluate the impact of different management practices.

The influence of various forms of farming on unmanaged grasslands was monitored with regard to the accumulation of the above-ground biomass (litter + mulching) and its influence on the leakage of rainfall and the amount of elements in lysimetric waters. In 2001-2005, the highest accumulation was observed in variants 1× mulched in the later term and on green fallow (on average 2.11-1.13 t of dry matter/ha). In comparison with the control site, a conclusive increase always occurred. An interannual increase of dry matter amounted to 0.4-5.2% of the total above-ground biomass. A negative correlative dependency on rainfall leakage on this material was discovered; at a depth of 0.4 m 4-10% of the rainfall leaked, but it had a significant influence on the wash out of Ca, Mg and S. The leakage of water affected a wash out of N_min, P, K, Ca, Mg and S more than the weight of dry matter of the above-ground biomass. With the exception of P, the elements showed a downward tendency over five years. The above-mentioned forms of farming annually increased the accumulation of the above-ground biomass by 0.05-0.16 t of dry matter/ha; however, they do not endanger underground waters by washing out minerals. After a five-year period, a disturbance of the ecological stability of grassland did not occur.

Deoxynivalenol (DON) is the most prevalent Fusarium toxin in Czech wheat samples and therefore forecasting this mycotoxin is a potentially useful tool to prevent it from entering into food chain. The data about DON content in wheat grain, weather conditions during the growing season and cultivation practices from two field experiments conducted in 2002-2005 were used for the development of neural network model designed for DON content prediction. The winning neural network is based on five input variables: a categorial variable - preceding crop, and continuous variables - average April temperature, sum of April precipitation, average temperature 5 days prior to anthesis, sum of precipitation 5 days prior to anthesis. The most important input parameters are the preceding crop and sum of precipitation 5 days prior to anthesis. The weather conditions in April, which are important for inoculum formation on crop debris are also of important contribution to the model. The weather conditions during May and 5 days after anthesis play only an insignificant role for the DON content in grain. The effect of soil cultivation was found inferior for model function as well. The correlation between observed and predicted data using the neural network model reached the coefficient R² = 0.87.

The objective of this study was to evaluate the influence of organic (cattle manure) and inorganic fertilizers [composite NPK (15:15:15)] and natural zeolites on soil properties, vegetative growth and yield of apple plants grown on vertisol under Cacak conditions (Western Serbia). The results showed that the combined fertilization induced a decrease in acidity, an increase in humus content, a partial increase in total nitrogen (NTOT), and, primarily, a rise in available phosphorus (P) and potassium (K) levels. A highly significant (P < 0.01) interactive effect of the apple cultivars and nutrients on one-year-old shoot length and trunk cross-sectional area (TCSA) and a significant effect (P < 0.05) on yield per tree and yield per hectare were determined.

In this work, the effects of double, triple and quadruple combinations of gibberellic acid, kinetin, 24-epibrassinolide and polyamines (cadaverine, putrescine, spermidine, spermine) on the stomata movements in the leaves of barley seedlings grown under saline conditions were studied. In the control seedlings, the stomata number, stomata index and stomata length increased in the upper surfaces of leaves in comparison with their lower surfaces. In addition, the epidermis cell number in the leaves of control plants were fewer in the upper surface than that in the lower surface, but the stomata were statistically in the equal width in both surfaces. As for the applyings, they generally decreased stomata number, stomata index, stomata length and epidermis cell number, while they increased the stomata width in the upper and especially in the lower surface according to the control. The growth regulators used may have served to adaptation of barley seedlings to saline conditions by causing a decrease in most of the mentioned parameters.

Sequencing of cereal genomes is not a feasible task due to their large size and high content of repetitive DNA sequences. There are two basic approaches to simplify analysis of such genomes: reduced representation approaches, such as EST sequencing, methyl filtration and Cot-based cloning and sequencing; on the other side there is analysis of genomes in a step-wise manner, e.g. through creation of chromosome-specific genomic resources. Combination of both approaches - i.e. Cot-based cloning and sequencing of DNA obtained from a chromosome-arm-specific BAC library - was tested in this work.

The effects of putrescine (a polyamine), low temperature and their combinations on the activities of apoplastic antioxidant enzymes were studied in the leaves of two wheat cultivars, winter (Dogu-88) and spring (Gerek-79). Fifteen-day-old wheat seedlings were treated with putrescine solutions (0.1, 1 and 10mM) prior to cold treatment (5/3°C). The activities of apoplastic catalase, peroxidase and superoxide dismutase were determined in the leaves both under normal and cold conditions at 1, 3 and 5 days. The results indicate that cold treatment significantly increased the activities of apoplastic catalase, peroxidase and superoxide dismutase in winter wheat while not generally affecting spring wheat. Under control conditions, the putrescine treatments were more effective in increasing the enzyme activities in winter wheat than in spring wheat. However, under cold conditions, the putrescine treatments surprisingly induced enzyme activities in spring wheat while generally reducing those in winter wheat leaves. The results show that putrescine may act as an agent inducing primary changes in the apoplastic antioxidant system of wheat leaves during reactive oxygen species-mediated damage caused by low temperature stress.

The genetic diversity and the relationships among rapeseed germplasm, including a collection of 20 Chinese, 25 Czech, 2 German, 2 French, and 1 English cultivars and breeding materials were evaluated using random amplified polymorphic DNA (RAPD) markers. A total of 79 different polymorphic amplification products were obtained using10 selected decamer primers. RAPDs revealed a significant level of polymorphism among the accessions. The diversity index (DI) ranged from 1.390 to 3.491, showing a sufficient potential of selected primers to differentiate among studied genotypes. Three different metrics were used to assess genetic diversity. The best fit between a priori knowledge about germplasm origin and a posteriori grouping was found using Hamman metrics. Cluster analysis based on Hamman pairwise distance comparison divided the studied accessions into three main clusters. The first group included only accessions fromChina, the second group only that fromEurope with the exception of Zhongshuang No. 2, a Chinese winter rape possessing European cultivars in the pedigree. The third group included accessions both fromChina andEurope. The results indicate the occurrence of a considerable genetic variation between Chinese and European accessions.

The effect of chemical weed control with reduced herbicide rates (pre-em., pre-em. + post-em., post-em.) on weed population density and maize yield was compared in three tillage systems (mouldboard, chisel, disk harrowing) for lessive pseudogleyic soil in north-eastern Croatia(1997-1999). These main weeds were present in all tillage variants: Echinochloa crus-galli (L.) PB., Chenopodium album L., Ambrosia artemisiifolia L., Polygonum lapathifolium L., Equisetum arvense L. and Calystegia sepium (L.) R.Br. The density of all weeds was significantly affected by tillage and it ranged from 204 plants on untreated plots with mouldboard to 372 and 421 plants per m2 with chisel ploughing and disk harrowing, respectively. In comparison with standard tank-mixture of atrazine herbicide (metolachlor 50% & atrazine 20%) at the recommended rate, atrazine-free herbicide combinations (metolachlor + 50% prosulfuron & 30% primisulfuron-methyl; sulcotrione + bromoxynil; thifensulfuron-methyl + nicosulfuron) showed a similar total efficacy of weed control (95-96%). Band spraying with standard treatment at a half-recommended rate combined with mechanical weed control brought a satisfactory total weed reduction (83-87%). The weed control methods had no effects on maize yields that were significantly affected by year and tillage. Compared to the highest yield with mouldboard ploughing (10.2 t/ha), average percent yield depressions with chisel ploughing and disk harrowing were 10 and 22%, respectively.

The Cd and Zn accumulation and phytoextraction potential of seven willow clones was investigated in a pot experiment for two vegetation periods. Heavily polluted Fluvisol-Litavka, moderately contaminated Cambisol-Pribram, and unpolluted control Chernozem-Suchdol were used. Significant differences were found in Cd and Zn accumulation between the willow clones. Cd and Zn were transferred from roots to aboveground tissues and all tested clones confirmed higher Cd and Zn accumulation in leaves than in twigs. Cd and Zn amounts removed by willow leaves were the highest from the most polluted soil (up to 83% Cd and 71% Zn of total removal). Therefore the harvest of leaves is necessary if willows are planted for heavy metal phytoextraction. Although the extremely high Zn contamination of Fluvisol-Litavka significantly reduced biomass production, willows planted in this soil showed the highest Zn removal because of extremely high Zn accumulation (max. 5061 ppm in leaves). Clones planted in moderately contaminated soil achieved the highest Cd removal. Clones showed different abilities to remove Cd and Zn, which was dependent on soil type and contamination level. Remediation factors were determined less than 1% for Zn in the heavily polluted soil and also unsatisfactory for Cd. However, it was shown that willows were suitable phytoextractors of moderately contaminated soil. About 20% of Cd and 4% of Zn were removed by harvested biomass from the total content of soil after two vegetation periods.