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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.

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.

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.

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.

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.

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.

The effect of nitrogen fertilization on root length (RL) distribution of winter wheat (Triticum aestivum L.) was investigated. The study was conducted in Prague-Ruzyne on clay loam Chernozemic soil in the years 1996-2003. Two (N0, N1) and three (N0, N1, N2) treatments, unfertilized (N0), fertilized with 100 kg (N1) and 200 kg N/ha (N2) were studied in 1996-2000 and 2001-2003, respectively. Nitrogen rate 100 kg/ha had no effect on RL in soil layers (P > 0.1) in years 1996-2000 and 2002-2003 and there was not significant interaction between N treatment and soil layer except for year 1998 (P < 0.01). Nitrogen fertilization affected RL distribution significantly (P = 0.013) only in 2001 due to reduction of root growth in subsoil layers in treatment N2 (200 kg N/ha) in comparison with N0 and N1. The effect of N fertilization on total RL in rooted soil volume was insignificant. There was a significant effect of year on total RL (P < 0.01) but not of interaction of year and N treatment. Roots reached, with the exception of two years, the depth between 100 and 130 cm. Nitrogen fertilization (N1) had no effect (P = 0.59) on rooting depth (RD) in years 1996-2000 but there was a significant effect of interaction between year and N fertilization on RD (P < 0.01). In the second experimental series (2001-2003) N fertilization rate 200 kg N/ha significantly reduced maximum RD (P < 0.01) in comparison with N0 and N1. The year had highly significant effect on RD.

he study was undertaken to determine a possible role of polyamines (putrescine, spermidine, spermine) as antioxidants in salt tolerance of Chamomilla recutita and Origanum majorana. Salinity generally induced variable changes in growth, contents of oil and flavonoids of both plants; foliar application of any polyamines counterbalanced the effects of salinity. In general, the degree of stimulation differed according to the type and concentration of the used additive and the type of the plant.

The effect of 24-epibrassinolide and 28-homobrassinolide on seed germination and seedling growth of radish (Raphanus sativus L.) was studied under cadmium toxicity. The impact of brassinosteroids (BRs) on free proline levels and the activity of antioxidant enzymes catalase (CAT; EC 1.11.1.6), peroxidase (POD; EC 1.11.1.7), superoxide dismutase (SOD; EC 1.15.1.1), ascorbic peroxidase (APOX; EC 1.11.1.11) and guaiacol peroxidase (GPX; EC 1.11.1.7) in radish seedlings under Cd toxicity was evaluated. The effect of BRs on the activity of ascorbic acid oxidase (AAO; EC 1.10.3.3) and lipid peroxidation in radish seedlings challenged with Cd stress was also investigated. BRs supplementation alleviated the toxic effect of the heavy metal and increased the percentage of seed germination and seedling growth. Out of the two substances, HBL was found to be more effective than EBL in stress alleviation. HBL (3µM) alleviated the toxic effect of the heavy metal and increased the percentage of seed germination by 57% over Cd and 20% over unstressed control. Similarly supplementation of HBL (3µM) caused an increase of 156%, 78% and 91% in length, fresh weight and dry weight of seedling, respectively, over Cd treatment alone. The amelioration of seedling growth by BRs under metal toxicity was associated with enhanced levels of free proline. The activities of antioxidant enzymes CAT, SOD, APOX and GPX were increased in the seedlings from treatments with Cd along with BRs. Brassinosteroid treatment reduced the activity of POD and AAO in heavy metal stressed seedlings. Lipid peroxidation induced by Cd was found reduced with the supplementation of BRs. The results obtained in the study clearly indicated the ameliorative influence of brassinosteroids on the inhibitory effect of Cd toxicity.

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.

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.

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 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.

A direct and secondary effect of liming and organic fertilization on the cadmium content in soil and in vegetables was examined. Celeriac (Apium graveolens L. var. rapaceum) was cultivated in the first year after lime application and organic fertilization whereas leek (Allium ampeloprasum ssp. porrum J. Gay) was grown in the next year. Soil was limed with a calcium carbonate fertilizer at the rate of 2.0 t CaO/ha. The following were applied as organic fertilizers: farmyard manure (60 t/ha), rye straw (4 t/ha), rye and winter vetch, both the plants cultivated as winter catch crops for green manure. Liming significantly reduced the available cadmium content in the soil in the first and second year after its application. Also, it significantly reduced the cadmium content in celeriac and leek compared with no-liming cultivation. Organic fertilization, especially farmyard manure and straw, significantly reduced the soil available cadmium content as compared to the untreated control (without organic fertilization). The aforementioned factor significantly reduced the cadmium content in the examined vegetables. Cadmium lowest content in celeriac leaves and leek was recorded after the application of farmyard manure. A combined application of liming and organic fertilization in the form of farmyard manure most beneficially influenced celeriac leaves with respect to their cadmium content.

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.

It has been demonstrated that endophyte-infected (EI) ryegrass performed better in response to N deficiency than its endophyte-free (EF) counterpart. When P is considered, there is a lack of related information. In this study, Lolium perenne L. infected with Neotyphodium lolii was employed to establish EI and EF populations. Soil-grown EI and EF ryegrass were tested for their responses to P deficiency. The results showed that the endophyte infection improved the adaptability of ryegrass to P deficiency. When P was limited, EI roots were significantly longer (EI, 398.8; EF, 323.4 m/pot) and heavier (EI, 30.58; EF, 23.20 g/pot) than EF roots; the root: shoot ratio of EI plants was greater than that of EF plants (P < 0.05). The content of total phenolics and organic acids was significantly greater for EI roots than for EF roots at low P supply; the concentration of both, however, was not improved by the endophyte infection. This suggested that it was the higher root dry weight (DW) that contributed to the higher content of total phenolics and organic acids for EI plants, and the endophyte infection might have negligible effects on chemical modification of perennial ryegrass. Endophyte infection did not increase P uptake rate but did significantly improve P use efficiency of ryegrass in response to P deficiency (EI, 0.734; EF, 0.622 g DW/mg P).

The key focus of the project "Bringing the datawarehouse for agriculture into practice" is to develop an IT solution for the implementation of data integration in agriculture. This solution is elaborated in cooperation with a whole range of bodies in the Czech Republic; the lead partner is the Pardubice region where the pilot phase of datawarehouse implementation is being performed. Apart from Czech legal subjects, partners from Finland, Estonia and Poland are also participating in the eFarmer operation. The datawarehouse project is one of the biggest subprojects of the eFarmer operation and is directly connected to the subproject of "Analysis of data and information flow and storage in rural regions", which was carried out within the eFarmer operation in the last period.

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.

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 apparent uptake of mineral nitrogen (N_min) from top- and subsoil layers during the growth of winter wheat (Triticum aestivum L.) was studied in Prague-Ruzyne on clay loam Chernozem soil in years 1996-2003. Two (N0, N1) and three treatments, unfertilized (N0), fertilized with 100 kg (N1) and 200 kg (N2) nitrogen per hectare were observed in years 1996-2000 and 2001-2003, respectively. The apparent uptake of nitrogen from soil layers was calculated from the changes of N_min content between sampling terms. Most of available mineral N in the soil down to 90 cm was almost fully depleted between tillering and anthesis in treatment N0. The uptake from subsoil layers was delayed and it continued during the period of grain filling in fertilized treatments. Nitrogen fertilization reduced utilization of N from subsoil. The apparent uptake of N from the zone 50-120 cm ranged from 21 to 62 kg N/ha in N0 and from 15 to 60 kg N/ha in N1 in years 1996-2000. In years 2001-2003 the corresponding values (50-130 cm) were 24-104 kg, 43-130 kg and 29-94 kg N/ha in treatments N0, N1 and N2, respectively. The uptake from 120 (130)-150 cm was around zero in a half of experimental years, and it reached at maximum 12 kg/ha in N0 in 1997. There was a strong linear relation between the amount of N_min in spring and the depletion of nitrogen from the zone 50-120 (130) cm, R² = 0.94, 0.91 and 0.99 in N0, N1 and N2, respectively.

The seeding rate of 2 mil viable seeds of mountain brome cv. Tacit (28.1 kg/ha) is sufficient to establish a productive stand. The seeding amount can be decreased in the mixture with legumes. The growing in pure stand or in a simple mixture, e.g. with alfalfa, is appropriate, because of its low competitiveness. Mixtures with red clover were slightly worse, and mixtures with white clovers, resp. other grasses less suitable. The optimal cutting height of mountain brome to 5-8 cm with regard to forage yield and persistence. Although this grass does not have special demands on site, it does not tolerate long-term dampness and floods. It is mainly used as silage grass with high dry matter production potential, with forage of better-than-average nutritive value, which is kept till the stage of early flowering.

The Příbram region belongs to the most polluted areas in the Czech Republic. Atmospheric deposition of potentially toxic elements from lead smelter represents the main source of contamination in this region. In this study, the most polluted location intensively used for agriculture situated northeast from the source of contamination was investigated. The individual sampling points were positioned by GPS and representative samples were taken from 0-60 cm split into three20 cmlayers. In the soil samples total Pb and Cd contents, plant available contents of these toxic elements and soil pH were determined. The total Cd content at the investigated site reached up to 13 mg/kg and Pb up to 2500 mg/kgin the top layer. The concentration of both elements decreases with depth and in the 40-60 cm layer the maximum content of only 6 mg Cd/kg and 400 mg Pb/kg was found. The plant available the content of Pb and Cd in the soil is related to the pH value. The correlation coefficient of exponential regression for Cd is -0.799 and for Pb is -0.787. The obtained data was processed by Surfer 7 software resulting in digital maps of horizontal and vertical contamination of this location. This observation confirmed the airborne source of soil contamination. However, some of the individual sampling points suggested local geogenic contamination of the soil where more detailed further research is required.

Six wheat varieties/lines and six derived F₂hybrids were studied to ascertain and compare heritability and genetic advance for flag leaf osmotic pressure, flag leaf water potential, flag leaf venation, flag leaf area and flag leaf thickness. Most of these characters had high heritabilities and expected a genetic advance. Prospects of a genetic improvement for all the characters studied are evident. The most promising cross combinations are PASBAN-90 × SARC-5 and SH-2002 × SARC-5. These traits therefore deserve a better attention in future breeding projects for evolving better wheat for stress environments.

Biofertilizers have been used as sources to improve plant nutrients in sustainable agriculture. Experiments were conducted to evaluate the potential of phosphate solubilizing bacteria (PSB) Bacillus megaterium var. phosphaticum and potassium solubilizing bacteria (KSB) Bacillus mucilaginosus inoculated in nutrient limited soil planted with pepper and cucumber. Results showed that rock P and K applied either singly or in combination did not significantly enhance soil availability of P and K, indicating their unsuitability for direct application. PSB was a more potent P-solubilizer than KSB, and co-inoculation of PSB and KSB resulted in consistently higher P and K availability than in the control without bacterial inoculum and without rock material fertilizer. Integrated rock P with inoculation of PSB increased the availability of P and K in soil, the uptake of N, P and K by shoot and root, and the growth of pepper and cucumber. Similar but less pronounced results were obtained when rock K and KSB were added concomitantly. Combined together, rock materials and both bacterial strains consistently increased further mineral availability, uptake and plant growth of pepper and cucumber, suggesting its potential use as fertilizer.

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.

Field experiment demonstrated the benefit resulting from biological soil management including the use of N₂-fixing and growth promoting bacteria A. brasilense B-4485 for long-fibred flax. Seed inoculation by A. brasilense B-4485 was equivalent to the introduction of 15 kg/ha of N that provided the possibility of partial flax N requirement supply. Treatment A. brasilense + N₁₅P₆₀K₉₀ is considered to be the most profitable management in regard to flax yield and its quality, and is comparable to N₃₀P₆₀K₉₀ treatment. Biological management allows preventing high concentrations of N in soil, excludes lodging and negative effects on flax yield and its quality. Implementation of biological management for flax nutrition may be profitable for both ecology and economy of long-fibered flax growing.

The influence of tillage (conventional and non-tillage) on selected soil microbial properties was studied. The experiment focused on tillage that was launched in Prague-Ruzyne in 1997. The experiment included the following variants: conventional tillage, protective tillage (without post harvest residues), protective tillage (with residue biomass - mulch), protective tillage (covered by pea crop residues for winter wheat, with fore crop). In the field experiment there were tested: enzymatic activities (activity of urease, dehydrogenase, arylsulfatase and invertase) and microbial biomass. The microbial biomass and soil microbial processes were affected by tillage. Our results show the positive influence of protection tillage on selected biological parameters, especially in variants where soil was supplied with organic matter.

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.

Pea seeds were swollen in solutions with different concentrations of cytokinin benzyladenine (BA). As compared with controls, a low concentration of BA (0.05 mg/l) did not affect the growth of stems and roots of twelve-day-old seedlings but concentrations of 0.20-4.00 mg/l showed an inhibiting effect; this inhibition was proportional to the concentration of BA. In controls the ratio between the lengths of stems and roots was equal to 1.14, while in seedlings influenced by BA in concentration of 0.20 mg/l its value was significantly lowered to 0.91. Also in six-day-old pea seedlings cultivated under in vitro conditions, BA concentrations of 0.70 and 3.30 mg/l inhibited the growth of roots and epicotyls and significantly increased the production of ethylene (by 150 and 330%, respectively). Three hours after the amputation of the root of five-day-old pea seedlings the level of cytokinin trans-zeatin increased in the apical part of the stem. Within the interval of 48 hours after the amputation of the root the concentration of this plant hormone gradually decreased again. The initial increase in the zeatin level in the stem indicates that the absence of the root induces a reduction of growth-inhibiting effects of roots, which negatively influences the zeatin level in the stem apex at the beginning of germination.