Fulltext search in archive

A morphometric study of Amaranthus cruentus, A. retroflexus and their hybrid, A. × turicensis based on 75 plant samples (750 inflorescences), collected throughout the Olomouc-Holice area (Czech Republic), is presented. Using multivariete methods (including cluster analysis and canonical discriminant analysis), the existence of three groupings of plants was proven. The hybrid exhibited intermediate values of the width and length of female tepals, length of awl-shaped bracts, and seed size when compared with parental species. A germination experiment showed that dark seeds of A. × turicensis as well as dark seeds of A. retroflexus germinate scarcely and independently on the day length while light seeds of A. cruentus germinate promptly and markedly better under a short day regime. The chromosome analysis showed that A. retroflexus, A. cruentus, and A. × turicensis have the same chromosome number 34.

The influence of seed inoculation with a bio-preparation of nodule bacteria Rhizobium leguminosarum, fertilization of 0, 40, 80, 120 kg N/ha and molybdenum topdressing on the yield of green mass, dry matter, seed, average number of pods per plant, average number of seeds per pod, average nodule number per plant, nodule dry weight as well as plant and seed protein concentration were studied during the two years of investigations on two soils - Mollic Gleysols and Eutric Cambisols. The highest values of all investigated parameters were obtained in the inoculated seed variants with molybdenum application, except the average nodule number per plant where the highest values were achieved in variants without molybdenum. The effect of nitrogen fertilization depended on the soil type, i.e. its chemical properties. The largest number of the investigated parameters obtained the highest values as a result of fertilization with 40 kg N/ha on Mollic Gleysols (3.96% humus). Thus, seed yield was 4.02 t/ha, nodule dry matter 0.482 g per plant whereas seed protein concentration was 26.91%. The largest number of the investigated parameters on Eutric Cambisols (1.07% humus) obtained the highest values with fertilization of 80 kg N/ha where seed yield amounted to 3.65 t/ha, nodule dry matter 0.456 g per plant while seed protein concentration was 26.48%.

Immature zygotic embryos are frequently used for induction of cell cultures in vitro and for genetic transformation. The effect of three synthetic auxins: 2,4-dichlorophenoxyacetic acid (2,4-D), 3,6-dichloro-2-methoxybenzoic acid (dicamba) and 4-amino-3,5,6-trichloropicolinic acid (picloram) on induction and subsequent regeneration capacity of barley. In vitro culture was studied in 12 spring barley cultivars registered in the Czech Republic and a variety of Golden Promise, with known high regeneration efficiency. The callus formation frequency and number of green regenerants were influenced significantly both by genotype and auxin. Most cultivars formed statistically significantly a higher mean number of regenerants (1.95) after the callus induction on the medium with 2.4-D as compared to the media with picloram and dicamba. Only two cultivars (Nordus and SG-S-261) did not respond to the used auxins differently. The highest average number of regenerants (from all three auxins) was obtained with Golden Promise (2.7 plants per one cultivated scutellum). From the set of genotypes used in our study, the cultivars Atribut, Forum, and Scarlett with the mean number of regenerants (2.09-1.57) would be the most suitable cultivars for further transformation use. They differ statistically significantly from the cultivars Nordus, Amulet, Akcent, SG-S-252, Orbit, and Granát (0.42-0.92) which had the lowest mean number of regenerants.

European winter wheat landraces and obsolete cultivars (121 accessions in set I and 101 accessions in set II) with modern check cultivars were evaluated in three-year field trials. Increased spike productivity in modern cultivars could be attributed mainly to increased number of grains in spikelet and increased HI, whereas TGW has marginal effect. Old cultivars had on average by 2-3% higher crude protein content in grain than modern ones. Among selected 10 characters, relatively wide diversity (C.V. 11-20%) has been estimated in spike length and characters of spike productivity (except of grain weight with C.V. close to 9%). It was difficult to distinguish the cultivars according to the country of origin, however, earliness and lower spike productivity seems to be characteristic for South-East origin whereas cultivars from North-West Europe showed opposite characters. Correlation analyses showed close relations between earliness in heading and in maturity and negative relation between late heading and grain filling period, which was positively correlated with TGW and HI (r = 0.26 to 0.38). Number of grains in spikelets was highly correlated with spike productivity and HI (r = 0.62 to 0.69) whereas relations between these two characters and TGW were lower (r = 0.20 to 0.51). Spike productivity characters, except of TGW, are in negative correlation with crude protein content in grain (r = -0.34 to -0.50). Regression analyses confirmed that main determining character for the spike productivity is number of kernels in spikelet (about 40% of variation) while effects of TGW are about half-size. Crude protein content was positively affected by plant height (15-30% of variation) impact of grain weight per spike was lower (14-17% of variation) and negative. Potentially valuable donors of earliness and longer grain filling period were identified for further studies and/or utilization in breeding programs. As especially valuable character can be considered very high crude protein content (around 18% in cvs Berg-land, Ukrajinka, Sippbachzeller, Innichen Nr. 25001 and Barbu du Finistre). High crude protein content combined with relatively good spike productivity and/or long grain filling period or earliness was found in cvs Visperterminen 640 E, Hatvan, Szekacz 1242, Berchtesgardener Vogel, Ble du Lot and Barbu du Finistere.

A polyfactorial field trial with alfalfa (Medicago sativa L.) cv. Palava, Jarka and Vlasta was established in Červený Újezd (altitude405 m a.s.l., average year precipitation493 mm per year, average year temperature 7.6°C, clay loam orthic luvisol) in the spring with a companion crop (spring wheat) in rows of a space of125 mm, sowing rate 16 kg/ha of germinable seeds in the year 1998. The stands were cut 3 times per year, the control variant was left without a treatment, the rest were cultivated with a spike or a vibration harrow before the beginning of the vegetation season and after the first cut. The numbers of plants and stems per m2 and dry mass yields were measured. The results were evaluated by four-factor analysis of variance Anova and by regression analysis. The harrowing of the stands resulted in a significantly lower amount of plants per m2 in the end of the fourth year by 23-29%, on average a lower number of stems per m2 (by 13% using double cultivation per year with the vibration harrow). The dry mass yield was significantly influenced only with cv. Jarka (by 5-11% higher in the cultivated fields). The moderately or relatively strong relationship between the plants amount and the time was exponential.

Between 1996-2002, successional dynamics on an abandoned pasture in Přední Ždírnice (lat. 50°32'N, long. 15°40'E) was examined. A 7-year study was performed on the abandoned mesotrophic pasture classified as Cynosurion Tüxen 1947 at the start of the study. Two permanent plots (100 m²) were established and sampled three times a year; changes in plant species composition (species cover) and plant species diversity (species number) were studied. Species assemblages of the Cynosurus pasture were described, E1 (herb layer) and E2 (shrub layer) covers were calculated and a secondary succession in the plant community was evaluated. Abandonment caused the decrease in the cover of the species sensitive to shading - e.g. Taraxacum sect. Ruderalia, Trifolium repens, Lathyrus pratensis, Plantago major, Stellaria graminea, Vicia cracca. Contrary to this, the cover of Calamagrostis epigejos, Rubus sp., Galium album, Galium verum, Knautia arvensis, Veronica chamaedrys increased, probably due to their ability to spread by clonal growth and as a result of the competitive relationships in the plant community. A big production of Calamagrostis epigejos litter may be the outcome of a significant decrease (by 9%) in E1 cover (P = 0.04). Although the grassland was invaded by ruderal and weedy species (Apera spica-venti, Myosotis arvensis, Veronica arvensis) and by shrubs Crataegus sp. and Rosa sp. (an increase by 16%), an increase in species number was not significant. Phytosociologically, the Cynosurion Tüxen 1947 community came closer to the Arrhenatherion Koch 1926 alliance.

The mode of inheritance of yield, topping height, leaf number, days to flowering, leaf length and width was studied by means of graphic analysis in a half diallel cross test of four burley tobacco varieties (Saturn, TN 86, Bs 92 and Bols 100) in 1998 and 1999. The trial was set up according to the RCBD at four replications in the experimental field of Tobacco Institute Zagreb in Pitomača. Overdominance in inheritance of all studied traits, except leaf length and width in 1998, was found by the graphic method. No interallelic interaction and epistasis were present as seen from testing regression coefficients for all investigated traits and years. The distribution of parental genotypes on a scatter diagram along the expected regression line points to the genetic divergence of the parents. Parent Bs 92 appeared to have the most dominant alleles for yield and leaf length and parent Saturn for topping height, leaf number and leaf width.

CAPS (Cleaved Amplified Polymorphic Sequence) method and standard infection tests were used for the study of tomatoes (Lycopersicon esculentum L.) resistance against the root-knot nematode (Meloidogyne incognita Kofoit and White). The CAPS method was used to determine genotypic constitution of M_i gene in ten Czech and four foreign varieties of tomatoes. Similarly were verified one hundred and twenty individuals of F₂ segregated progeny of Nema variety and the same number of F₂ progeny of Petopride variety. A comparison of results of infection test with results of molecular-genetic analyse of DNA showed 100% congruence in detection resistant (susceptible respectively) genotypes. Result of ² test confirmed in the level of mathematical expectation P (0.5, 0.7) congruence between actually obtained and theoretical segregation ratios. The CAPS method can be recommended for fast and precise determination of resistance or susceptibility of tomato plants against the root-knot nematodes. The goal of the method is the possibility of detection of genotypic constitution of M_i gene that can significantly accelerate the process of creation of new resistant varieties.

The efficiency of partial doses of nitrogen applied to poppy (Papaver somniferum L.) plants, cv. Opál, was followed in a pot experiment. The ammonium nitrate was applied either in a single dose at the beginning of growing season or in two split doses with the second application at the stage of flowering. With the increasing dose of nitrogen the number of capsules per a plant during the harvest and their volume increased irregularly. The separated application of an optimum dose of N (i.e.0.9 g N/pot) showed a statistically highly significant positive effect on the yield of poppy seeds compared to the same single dose of N made this figure increased by 25.6%. The morphine content in the capsules increased with the increasing supply of N from 0.85 to 1.01%. The term of nitrogen application influenced the number of capsules per a plant and their volume and morphine content irregularly.

The Czech University of Agriculture in Prague in cooperation with the Business Exchange in Hradec Králové operates an electronic business system EBS, which enables on-line exchange trade negotiations through the Internet. The system fully takes the advantage of possibilities and technologies of e-business, bringing thus forward new opportunities for making use of the exchange trade with agricultural and food commodities on the EU liberal market. The whole procedure is a part of the Agrarian www portal AGRIS.

Effects of the year, previous crop and control of leaf diseases on grain yield, test weight, protein and starch content, Fusarium head blight (FHB) and deoxynivalenol (DON) content in grain were investigated in four spring barley varieties. The trials were set up in 2001-2004 at Kroměříž (235 m above sea level, average annual temperature 8.7°C, annual precipitation sum 599 mm) in a five-course crop rotation, where spring barley followed the previous crops sugar beet, winter wheat, maize, and oilseed rape. The experimental years differed a lot in temperature and precipitation. The years 2001 and 2002 were dry and warm and grain yield was much lower as compared to that in the following years even though the other growing conditions were identical. The most stable quality parameters were obtained after the previous crop sugar beet. The average value of test weight was 661 g/l(ranging from 629 to 685 g/l), protein content 11.2% (10.3-11.7%) and starch content 61.5% (58.9-64.9%). Grain yield averaged 6.67 t/ha. Test weight after maize was on average 658 g/l(619-692 g/l), protein content 11.5% (10.1-12.4%), starch content 60.7% (59.2-63.8%), and grain yield 6.24 t/ha. Test weight and starch content were lower and protein content higher after oilseed rape and winter wheat. A higher FHB incidence and DON content were found after the previous crop maize. In 2001 and 2002 with strong water deficit during the growing seasons, more grains infected by Fusarium spp. were detected and DON content was higher too. The increase was due to a short rainy period at heading of spring barley. Problems of variable conditions for growing malting varieties of spring barley and current possibilities of producing both good grain yields and quality are discussed.

The priority of this study was to investigate how selenium influences toxicity of Cd, Zn, Cu and Pb when the metals appear in the hydroponic solution in pairs. As a model subject mustard seedlings (Sinapis alba L.) were used. Except phytotoxicity of individual metals and Se-metal combinations determined through photosynthetic pigments content (chlorophyll a, b, total carotenoids) also metal accumulation in the roots and shoots was determined by the AAS method. Se in all metal combinations reduced the unfavourable effect of other metals tested for chlorophylls content, however, for carotenoids primarily the opposite effect occurred. For metal accumulation in the roots and shoots it was confirmed that Se stimulated only Cd (about 24%) and slightly Cu (about 9%) accumulation in the roots, while in the shoots there was inhibited accumulation of all metals tested. The strongest inhibition was observed in Pb accumulation (84.9%). This fact indicates that Se generates some barriers for metal transfer from the roots to the underground plant parts. In contrast, Cu, Zn, Pb and Cd increased Se accumulation in the roots in the range of 4 (in combination with Cu) to 68% (in combination with Cd) and in the shoots in the range of 11 (in combination with Pb and Zn) to 44% (in combination with Cd). In the shoots only Cu inhibited Se accumulation (about 67%).

The aim of the study was to determine the response of soil enzymes such as dehydrogenases, urease and acid and alkaline phosphatases to heating oil contaminating (0.0, 0.25, 0.5, 0.75, 1.0, 1.5% of soil) the experimental soil supplemented with lime and used for cultivation of yellow lupine of the Markiz variety. An increasing contamination of soil with heating oil stimulated the activity of dehydrogenases and acid and alkaline phosphatases but had a toxic effect on yellow lupine. Lime supplements did not have a significant effect on an average activity of soil dehydrogenases. However, such soil treatment had a significant effect on urease. Increasing heating oil doses in lime-supplemented soil stimulated urease activity, whereas in lime-free soil urease activity was inhibited. The activity of acid and alkaline phosphatase was lower in limed soil than in lime-free soil. The activity of dehydrogenases, urease and alkaline phosphatase in the soil with lupine cultivation was significantly higher than in the unsown soil.

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.

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.

One of cereal diseases that has gained a greater importance for growers, processing industry as well as for breeders in many regions of the world is Fusarium head blight (FHB) caused by fungi of the Fusarium genus. The objectives of this study were to test diversity among spring barley breeding lines exhibiting various sensitivity to FHB and to find RAPD markers and AFLP markers that will distinguish between susceptible and resistant and/or moderately resistant genotypes. A test of a set of spring barley genotypes artificially infected by fusaria in field trials was carried out. Based on the results from field and laboratory evaluation and deoxynivalenol (DON) content assessment, barley genotypes with different responses to FHB were selected. The genotypes were hybridized and doubled haploid (DH) lines were derived in F₁ generation using the in vitro androgenesis method. Initial parental components and derived DH lines were tested for FHB infection and DON content. A set of parental genotypes of spring barley was tested with 80 RAPD markers. A RAPD marker (H30) was detected which enabled to distinguish between very susceptible parental genotypes and other resistant or moderately resistant spring barley genotypes based on the fragment of about 1300 bp. This specific product was screened in 23 DH lines derived from crosses of parental genotypes of spring barley and detected in 10 DH lines. During the study, some DH lines were selected that exhibited improved resistance to Fusarium infection. A low infection level and low DON content was found in the line DH 4/2 derived from CI 4196 × Foster. The AFLP technique was used to analyse parental genotypes of spring barley. The detected markers can be further evaluated and employed to select breeding materials.

In the years 1999-2003 the effect of covering rows of early potatoes with non-woven fleece on the yield formation, dry matter content in tubers, temperature of soil and of air in ground layer was investigated. Covering of rows enhanced the market yield of tubers at early harvest 60 days after planting in average by 35.8% in comparison with the uncovered control. At harvest 67 days after planting the difference in advantage of the covered variant were 17.2% and 85 days after planting the difference in yield between variants was already non significant. The yield effect of the fleece was affected by year (higher effect in the years with cold spring) and by variety (Impala responded at 60 days after planting by yield increase under fleece 43.7%, Adora 27.9%). Higher dry matter content of tubers by 0.87% was found in covered plants 60 days after planting in comparison with control. Cover enhanced average air temperature in ground layer by 2.0°C, in soil in depth 100 mm by 1.8°C.

The effect of osmotic stress on oxidative injury, compatible solutes content and water relations was investigated in two maize cultivars (Zea mays L. cv. Ankora - drought-sensitive and cv. Nova - drought-tolerant). Relative water content in leaves of both cultivars decreased after drought treatment, leaf water loss of sensitive cv. Ankora was higher than that of cv. Nova. The 24 h water stress induced by 0.3M sorbitol (-1.4 MPa) resulted in a damage of cell membranes. Lipid peroxidation rose in all studied organs of cv. Ankora and electrolyte leakage in roots of cv. Ankora was much higher than in cv. Nova. Similarly, proline content increased significantly in all studied organs of cv. Ankora. Content of soluble sugars increased in all studied organs of both cultivars, but the mesocotyl of cv. Nova accumulated the highest amount of sugars. The electrolyte leakage was the highest in the roots of both cultivars. Osmotic stress had deep influence predominantly on the roots of both cultivars. It is apparent that stress impact on the drought-sensitive cv. Ankora was deeper than on the drought-tolerant cv. Nova.

This study was conducted to determine the effect of row spacing (40, 60 and 80 cm) on forage dry matter (DM) yield and quality of four hybrids grown in the years 2001 and 2002. The highest DM yield was obtained from the Arifiye (24.1 and 22.4 t/ha) while the lowest DM yield was obtained from Pioneer 3163 (19.9 and 19.8 t/ha) in the years 2001 and 2002, respectively. As row spacing increased, DM yield as an average of two years decreased from 27.2 to 16.6 t/ha. No differences were found among row spacing for DM content, harvest index (HI) and ear content. As row spacing increased, whole-plant acid detergent fiber (ADF) and neutral detergent fiber (NDF) content increased from 214 to 227 g/kg and from 420 to 451 g/kg during the year 2001, respectively. However, ADF content decreased from 281 to 267 g/kg and NDF contents decreased from 530 to 515 g/kg with increasing row spacing during the year 2002. In this study, hybrids showed distinct differences for crude protein, ADF and NDF contents in both years. Forage quality parameter including ADF and NDF of Pioneer 3163, TTM 8119 and Karadeniz Yildizi were higher than Arifiye hybrid.

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.

Fertilization with tannery materials positively influenced the soil pH and increased the content of alkaline cations in soil. After four years of investigations organic carbon content decreased most in the soil fertilized with untreated sludge, mineral salts and in the control soil. Irrespective of fertilization used and year of studies cadmium occurred mainly in most mobile fractions (mobile, exchangeable and bound to manganese oxides). Copper was mainly bound in fractions less available to plants. After four years of studies an increase in mobile copper forms was registered in all treatment soils. Lead in the soil was present mainly in the form bound to organic matter and amorphous iron oxides. Distribution of lead points to the small share of this metal in the mobile and exchangeable forms, both immediately after fertilization applied and after four years of studies. Chromium became fixed in fractions less available to plants, mainly bound to iron oxides and in residual fraction. On the other hand, an apparent effect of fertilization with materials of tannery origin on this element total forms content was registered.

Soil bacteria belonging to the genus Azotobacter, Pantoea and some unidentified soil isolates were tested in vitro for phytohormone production under laboratory and soil conditions. The German wheat variety Munk was inoculated by several soil bacteria with exogenously applied hormones (IAA, 2,4-D) and a flavonoid(naringenin) with a half of the amount of recommended doses of fertilizers under greenhouse conditions. Most of the soil bacteria tested were able to produce indole acetic acid (IAA), and stimulated a lateral root development and colonization by the addition of 2,4-D and IAA. A formation of paranodules on roots as a result of crack entry invasion was observed with 2,4-D as well as with IAA. We were able to reisolate the organism from the paranodules and could establish the same results. Analyses for root exudates and in vitro phytohormone production by various bacterial isolates were also carried out, revealing that 2,4-D can be replaced either by high IAA producing bacteria or by exogenous application of IAA. Bacterial survival in the rhizosphere as well as the root and shoot weight of wheat plants were positively affected also by the addition of IAA, 2,4-D and naringenin.

Field trials were conducted at two sites Troubsko near Brno and Prague-Ruzyně in 1996-1999 with three varieties of safflower (Gila, CW-74, Sironaria). Three rates of nitrogen fertilization were used: N0 = no fertilization, N₁ = 40 kg/ha, N₂ = 80 kg/ha. Sowing rates were 50 and 70 germinable seeds per m2. The average values of oil content were highest in seeds of CW-74 variety (27.2%). Gila had on average the lowest oil content (24.5%). Linoleic acid was dominant in all three safflower varieties. Variation in content of linoleic acid in different years was not so high as in oil content. The highest average content of linoleic acid was found in Gila variety (81.2%), the lowest in Sironaria (77.4%). At Ruzyně average seed yield on dry basis was 2.7 t/ha and average straw yield was 7.56 t/ha. At Troubsko seed yield was 2.56 t/ha and straw yield was 3.69 t/ha (by 50% lower than at Ruzyně). The effect of year of growing and site on seed yields and on other parameters was highly significant. N fertilization increased safflower seed yield at Troubsko site only, where the dose of 40 kg/ha N increased the yield by 0.08 t/ha on average of years and the dose of 80 kg/ha N increased the seed yield by 0.2 t/ha in comparison with no nitrogen fertilization treatments. Increased N rates and especially higher plant density resulted in an increase in straw yields. Neither were thousand seed weight nor number of flower heads influenced significantly by different N rates or the above-mentioned differences in plant density.

The effect of different soil sampling procedures on the precision of estimating the weed seedbank in soil using three soil core samplers with a circular base of 1.3, 6.4 and 8.0 cmin diameter was studied in a model experiment. The results showed the importance of a methodological approach. The soil sampler with a larger diameter is more useful for the objective assessment of the species spectrum (detection of seeds of all weed species in the soil). Furthermore, the value of the coefficient of variation (vx) decreases along with the increasing diameter of the soil sampler. The value of vx assessed in partial samples taken with a sampler of 1.3 cm diameter was double to three times higher than for soil samplers of 6.4 and 8.0 cm. The value of vx increased in individual weed species at decreasing seed frequency in individual partial samples from 17.82 to 316.23%. The soil core with the diameter of8.0 cm on the area of1 m2 is optimal for the exact research. To estimate the weed seedbank in soil in small-plot experiments, one partial sample on the area of5 m2 is recommended. To obtain comparable results, it is necessary to take a higher number of samples at a decreasing diameter of the soil sampler. Likewise, a larger amount of samples is needed to detect less abundant species.

Microbial solubilization of hardly soluble mineral phosphates in soil is an important process in natural ecosystems and in agricultural soils. Regulation of the P-solubilizing activity by the presence of soluble phosphates in medium was determined. For this reason we decided to test a number of soil bacteria showing a high P-solubilizing activity for its sensitivity to the presence of soluble dihydrogen potassium phosphate in medium. At these studies, the direct determination of the solubilized phosphate in medium was masked by the presence of relatively high concentrations of soluble phosphate added. Therefore, we have modified the method, determining the residual tricalcium phosphate. The effect of soluble phosphate in medium on the P-solubilizing activity of rhizosphere isolates and strains of Rhizobium were tested in liquid cultures with the addition of various concentrations of soluble KH₂PO₄. The medium was filtered after incubation and the remaining tricalcium phosphate was separated by filtration. Filter papers with the remaining tricalcium phosphate were hydrolysed with 2N H2SO4. Phosphorus was determined spectrophotometrically. The P-solubilizing activity was expressed as a difference between the tricalcium phosphate added and its remainder after the incubation. These results fully confirmed that there exist the strains, whose P-solubilizing activity is inhibited and other strains, whose P-solubilizing activity is not inhibited or is inhibited very little in the presence of soluble phosphate. The use of our adapted method was much more suitable for this type of experiments.

The evaluation of technological characteristics of food wheat (Triticum aestivum L.), grown in a four crop rotation (corn, barley, pea, wheat) since 1994, is presented. Samples of grain, whole grain meals, and flours of the varieties Vlada and Samanta were analyzed. The samples originated from field trials at a research base nearNitra. All important methods of the assessment of the raw material technological quality (intended use for milling and baking) were applied. A total of 22 characteristics were evaluated (15 of them are shown in Table 1). The highest abundance of highly significant (significance levels being results of both parametric and nonparametric methods) changes (a £ 0.01) in quantity (grain and flour yield) and quality (gluten and its properties, water-binding capacity of flour, a-amylase activity) was observed between different years (7). The soil management methods (3; 2 + 1) had a significant (a £ 0.05) influence on the test weight (grain volume mass) and gluten content. In interaction with the year (as a factor), they significantly influenced gluten swelling number (Q-number) and highly significantly the activity of a-amylases. Highly significant differences were also found between varieties (2; 1/1), significant ones in interaction with soil management. Fertilization (3) and other interactions of factors were not statistically significant. Parameter means for factor levels (along with statistical significance of the influence of particular factors) and simple quality coefficients (used for the ranking of factor levels) are shown in Table 1.

Five cultivars of spelt wheat (Rouquin, Bauländer Spelz, Schwabenkorn, Franckenkorn and Holstenkorn) have been evaluated for baking quality by means of direct and indirect indicators. Three-year values of the indirect indicators have been statistically processed by the analysis of variance. Based on the results obtained we can say that all evaluated indicators except the extensibility of gluten were significantly influenced mainly by the year of growing. The cultivar itself was a less important source of variance, although some values of important indicators differed significantly according to cultivars. Based on indirect indicators such as the content of wet gluten, its extensibility and swelling, the content of N-substances, the sedimentation test in the modification with SDS, the falling number and the content of starch, the cultivars Schwabenkorn and Rouquin are considered as the most suitable and of the highest quality. In general all the cultivars of Triticum spelta L. showed high contents of N-substances (x = 15.46%) and wet gluten contents (x = 37.12%). Their disadvantages are lower swelling values (x = 9.3 ml) and lower sedimentation values (x = 37.4 ml) which have a negative influence on the bread volume and the specific volume (under 310 ml.100 g^-1). The predicted good baking quality of Schwabenkorn has been comfirmed in a baking experiment (direct method of evaluating the baking quality). There were good baking quality results for Bauländer Spelz as well. Unexpectedly bad results have been found with Rouquin, which showed the lowest water absorbing capacity of flour, the lowest bread volume, specific volume and baking extraction. The bread was just acceptable as far as taste is concerned. The baking from Holstenkorn was evaluated as excellent.

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

Traditional way of growing buckwheat (Fagopyrum esculentum L.) in Slovenia is stubble-crop production, but grown as a full-season crop it yields more. Genotypes that are adapted to stubble-crop system may not necessarily be the best adapted for the full-season crop. The objective of this study was to determine yield performance of two buckwheat genotypes under stubble-crop and full-season production system. The experiments (randomised block design) were conducted in Podravje region with two common determinant buckwheat genotypes (land race population and cultivar Darja) in 1997 and 1998. Buckwheat grown as a full-season crop had a greater leaf area index, more flower clusters, more developed seeds and 42% higher yield than the stubble-crop buckwheat. Although cultivar Darja had 10% less flower clusters than the land race population, the number of flowers and the number of developed grains were higher. The 35% higher grain yield of cultivar Darja was associated with larger leaf area index than land race population (4.0 vs. 2.3). Cultivar Darja outperformed the land race population under full-season crop production, whereas the yield difference between the two varieties was not significant under the stubble-crop production. These results suggest that the best yielding buckwheat genotypes should be determined separately for stubble-crop and/or full-season production system.