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In field experiments conducted on loamy luvic chernozem (170 m altitude, 48°34' N 17°45' E), the effects of undersowing time (5 days after maize was sown and into emerged stand) of lucerne, red clover and sainfoin on silage maize dry matter have been studied. The total dry matter yields were affected by time of undersowing of clover crops. The stands undersown after emergence of maize gave higher yields than former time of undersowing. The late time of undersowing improved conditions for growth of maize and formation of its yield. The number of maize plants had already insignificant effect on yields there. The dry matter weight, height, and number of maize plants and dry matter weight of weeds were main factors of formation of the total yield. The depressive effect of weeds on total yields was applied indirectly particularly through the decrease in the dry matter weight of maize plants. The path analysis in spite of the insignificant effect of clover crops undersown on total yields indicated some differences in the formation of yield. The number of maize plants reached the significant level of effect on yield only at stands with red clover undersown. On the contrary, the negative correlation of weeds dry matter weight with the number of maize plants reached level of significance in stands with lucerne undersown only.

In 1998-2000, in a multi-factorial field experiment established by the method of split blocks and subplots, we studied the effect of three systems of beet tops management, two sowing rates and two levels of N fertilization and the effect of interactions of the factors on production and qualitative indicators of spring barley varieties Amulet and Kompakt. The evaluation shows the dominant effect of the particular year on the variability of all characters. The proportion of the effect of the year on the variability of characters ranged from 2.1 (number of plants per m2) to 80.1% (yield). The variability of quality parameters was also considerably affected by the genetic factor of the variety (grain over2.5 mmsieve 40.4%, TGW 20.5%). The level of characters was greatly variable in relation to the course of climatic conditions of the year. The highest grain yield was achieved in 1999 (7.21 t/ha), the lowest one in 2000 (5.25 t/ha). The best quality parameters were shown by grain from the 1998 harvest (yield 6.20 t/ha) with significantly highest TGW (47.76 g), a high proportion of grain over2.5 mmsieve (92.01%, 5.54 t/ha) and a favourable content of N substances in the grain (10.60%). Ploughed down beet tops supported the creation of the yield, the average differences between variants were, however, minimal being heavily affected by the course of weather in particular years. More favourable conditions for the creation of the yield (6.17 t/ha) and for the formation of mechanical properties of the spring barley grain (TGW45.55 g, grain over2.5 mmsieve 85.86%) were produced by variants with late ploughing down beet tops, the smallest accumulation of N substances occurred in variants with harvested beet tops (11.83%). Sowing rate significantly affected values of all studied characters. Variants sown 4.5 MGS (6.27 t/ha) gave higher average grain yields, grain of better quality was obtained from the stands sown 3.5 MGS (TGW45.22 g, grain over 2.5 sieve 84.41%, N substances 11.93%). Between particular varieties, significant differences were found both in the economic yield and the grain quality. The Kompakt variety showed on average 4.7% higher yield (6.37 t/ha) than the Amulet variety which, however, reached the higher average TGW values as well as the proportion of grain over2.5 mmsieve (45.87 g, 88.24%). The grain quality of the Amulet variety was negatively affected by the increased accumulation of N substances in the grain (12.49%). As compared with control, N fertilization at the rate of 30 kg/ha showed significant increase in the yield in 1998 only (by 7.5%) while in other years, an increase in the yield was not noticed. In all years under investigation, the TGW values and the proportion of grain over2.5 mmsieve decreased and the content of N substances in grain increased after application of N at the rate of 30 kg/ha.

In Central Slovenia within a long term static experiment IOSDV we investigated the impact of mineral nitrogen (N) fertilisation (0, 65, 130, 195 kg/ha) on the N content and the N amount in winter wheat (larger roots, stems, spikes and leaves) in EC 81/82 and EC 90/91, employing three systems of management: farmyard manure ploughing in before forecrop maize, straw ploughing in and green manure, no organic fertilisation. At EC 81/82 the N content in larger roots was around twice as high as the N content in stems and around twice as low as the N content in spikes and leaves. There was 80% of the whole N amount in plant located in the spikes and leaves (33-168 kg/ha) in EC 81/82 and 90% in EC 90/91. Calculated N recovery from mineral fertiliser was 68-87%; it increased with the increasing N rates in the system with farmyard manure ploughing in and in the system with no organic fertilisation, but not in the system with straw ploughing in and green manure. Between EC 81/82 and EC 90/91 wheat gained from 4 to 34 kg N/ha, but there were more important translocations of N inside the plants, which were higher at higher mineral N rates. There was a significant impact of management system on the N uptake at the highest mineral N rate.

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

Two high yielding wheat (Triticum aestivum L.) varieties were pollinated with seven agrarian superior varieties. F₁'s thus obtained were pollinated with diverse winter maize lines/composites and treated with a solution containing 2,4-D and GA₃. The haploid embryos were rescued 13 to 16 days post pollination on MS₁ and MS₄ media. Out of 15, only two crosses viz., (UP 2338 × HD 2285) F₁ × maize and (WH 533 × PBW 343) F₁ × maize resulted in callus development and direct germination via embryo rescue.

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

A field trial with Bromus catharticus Vahl. cv. Tacit, Arrhenatherum elatius (L.) P. Beauv. ex J.S. et K.B. Presl cv. Median, Festuca pratensis Huds. cv. Otava and Dactylis aschersoniana Graebn. cv. Tosca sown in rows 125 mm, was established in the year 1996 in Prague (chernozem, altitude 281 m a.s.l., average precipitation 472 mm per year, average year temperature 9.3°C). The stands were cut one or three times per year. The mass was removed or once or twice mulched. The share of the botanical species (by weight method), number of present species and agrobotanical groups (grasses, legumes, other dicotyledonous) coverage were measured from the third to the sixth year of vegetation. The results were evaluated by the analysis of variance (Tukey α = 0.05) and by time series analysis (forecasting) by the Statgraphics Plus programme, version 4.0. The species number increased rapidly with the three times cut variant during the four years, from 4 to 25 species, under the other management it was in average from 7 to 14 species, in the sixth year. The highest share of the sown species with the lowest reduction during the years was at Arrhenatherum elatius (41-72% in the sixth year). Bromus catharticus was extinct in the fifth year. The species chosen had a higher importance for conserving of the original botanical composition than the way of harvest. There was the significantly lower ground cover with the variant one cut per year (on average less than 70%). Mulch covered 15-64% of the surface in dependence on the dry mass yield and mulching frequency. The plants coverage was highest on the two or three times harvested variants (75-80%D).

An application deals with calibration of neural model and Fourier series model for Ploučnice catchment. This approach has an advantage, that the network choice is independent of other example's parameters. Each networks, and their variants (different units and hidden layer number) can be connected in as a black box and tested independently. A Stuttgart neural simulator SNNS and a multiagent hybrid system Bang2 developed in Institute of Computer Science, AS CR have been used for testing. A perceptron network has been constructed, which was trained by back propagation method improved with a momentum term. The network is capable of an accurate forecast of the next day runoff based on the runoff and rainfall values from previous day.

Long-term fertilization of meadow stands affects the species composition, yields, and general pratotechnics. Observations were realised on a plane meadow of a mesophyte character in 1976-2000 years. Four variants were observed in the experiments (N0, N0P40K100, N100P40K100, N200P40K100) in four replications. Species composition of grass stands was variable in the followed period in the leaf area from 66 to 95% of the dominance (Table 1). Total abundance of species with PK-fertilization was almost identical in individual pentads (24-28 species) as it is evident in Table 2. Table 3 proves the highest dominance was found at Dactylis glomerata L. in the first five years. Rhizomatous grasses had the highest leaf area with 38-55% of the dominance on variants with the higher N doses (200 kg N/ha) + PK (Table 4). Table 5 demonstrates that the variant without fertilization showed nearly stable abundance of species with the higher than 1% (11-13). Reduction of species number especially with the dominance higher than 1% (5-11) followed at the highest N-fertilization in comparison with the check variant. The mean yield of dry matter was 2.75 t/ha, the stand fertilized by 40 kg P + 100 kg K/ha gave 30.6% increased of yield (Table 7). The highest yields were recording in the second year of the N-fertilization (8.28 and 10.12 t/ha).

Powdery mildew on barley (Hordeum vulgare L.) caused by the pathogen Blumeria graminis f.sp. hordei occurs worldwide and can result in severe yield loss. Because agronomical methods to control the disease are not completely effective, cultivars with genetic resistance are needed. Therefore, there is a need to describe new sources of genes that confer resistance to barley powdery mildew. This study was conducted to determine the genetic basis of resistance to powdery mildew in three selections 995-1-1, 995-1-2, 995-1-3 from barley landrace 995 (ICB 112840) collected in Al Aziziyah district, Tripolitania, Libya. Landrace originated from InternationalCenter for Agricultural Research in the Dry Areas - ICARDA, Aleppo, Syria. To determine the number of genes, the types of genes action and the gene loci in tested lines two types of crosses were made: (1) the lines were crossed to the susceptible cultivar Pallas, (2) the lines were crossed with Pallas isoline P22 carrying gene mlo5. The parents and progeny F2 were evaluated with isolate R303.1 for the powdery mildew resistance. Based on segregation ratios we found that resistance in these three selections was determined by a single recessive gene allelic to the Mlo locus occurring in Pallas isoline P22. In addition tested lines showed resistance reaction type 0(4) characteristic only for genes mlo. The value of new identified sources of highly effective powdery mildew resistance to breeding programs and barley production is discussed.

In 1999, the effect of increasing levels of nitrogen at the initial (13.9 mg.kg^-1) and increased (40 mg.kg^-1) level of watersoluble sulphur (S_wat) was studied in winter rape (cv. Lirajet) grown in pots. A synergetic effect of nitrogen on concentrations of Ca and Mg was demonstrated in the growth stages DC 20-29 and 31-39. Levels of P and K were balanced. In variants with a low content of S_wat in soil to 40 mg.kg^-1 of soil S concentration increased. With the increasing dose of N the content of S decreased from 1.00% to 0.78% and from 0.68% to 0.38% in DC 20-29 and DC 31-39, respectively. An increased level of S in soil changed the ratio N/S. In variants with a natural (i.e. low) content of S in soil, this ratio widened with the increasing dose of N from 8.06 to 25.15 while in variants with an increased level of S in soil it ranged from 3.24 to 5.85 in the growth stage DC 20-29. Increasing doses of N widened the ratio N/P regardless to concentration of S in plants. In individual growth stages the ratio P/S was markedly narrowed by changing contents of S in soil. The highest yields were obtained in the variant with an optimum concentration of all elements in plants and S contents above 0.6% and/or about 0.4% in growth stages DC 20-29 and DC 31-39, respectively. The obtained yields demonstrated a highly significant effect of N and S on seed yields. At a low concentration of sulphur in plants the yield of seed increased only to the dose N₃(i.e. 0.9 g N per pot); thereafter, it gradually decreased. An increased level of S in soil showed a positive effect on seed yields. Higher doses of N widened the ratio straw/seeds from 2.46 to 7.69; at higher levels of S in soil, an opposite trend was observed. In variants with a low content of S the number of branches and pods increased proportionally with increasing doses of N. On the other hand, increased levels of S reduced the number of branches and pods. At a low level of S in soil the total weight of seeds per pod decreased with the increased supply of N from 69.9 mg to 20.4 mg. At increased levels of S the weight of seeds per pod increased from 61.9 mg to 79.8 mg. Results of field experiments in four different localities corroborated a positive effect of S (in interaction with N) on its concentration in plants. The seed yield was significantly increased. In 2000, results from all localities were markedly influenced by climatic conditions; however average results of all experiments showed that S increased seed yields depending on the dose of N by 2.5 and 5.9%. An optimum nutrition of plants with all elements (including S) results in improved utilisation and increased yields.

This paper deals with the influence of Mg, N and the content of chlorophylls and carotenoids on photosynthetic productivity of two new genotypes of winter wheat, Lara and Perla, at two localities, Donji Miholjac and Kutjevo, during the vegetation periods 1997/1998 and 1998/1999. The applied parameters were determined by standard methods. The results showed effects of Mg concentration on all examined parameters with the exception of chlorophyll b content. The highest correlation coefficient was with the N concentration, significant correlation between the leaf area and N concentrations and between the leaf area and chlorophyll a. Statistical analysis showed very significant relationship between the content of organic matter and examined parameters with a large number of significant correlations. The most important correlation was found between the content of organic matter and N concentration, and between chlorophyll a, chlorophyll b, carotenoids and the content of organic matter. The link between N, Mg and other examined parameters was firm and significant as well as under strong influence of external factors.

Variability of grain yield components of some new winter wheat genotypes (e.g. Lara, Lenta, Kruna, Fiesta, Perla, and one line of AG-45) was examined. The analysis of grain yield components of these genotypes and the line was undertaken in a two-year research (1997/1998 and 1998/1999) at two different locations. Significant differences among genotypes, locations and research years were established. In the first experimental year (1997/1998) there was a high positive correlation between nearly all components of the grain yield. The most significant correlation was found between the grain number per spike and grain yield. In the second experimental year (1998/1999) the components did not show statistically significant correlation with the grain yield. It seems that the grain yield of examined genotypes depended significantly on the grain number per spike, grain mass per spike, and agroecological conditions during the vegetation period, whereby the potential yield was determined by the interaction among genotypes, location and production year. The biggest differences among examined genotypes of winter wheat were found in the stem height and spike length.

Tilletia controversa and Tilletia caries were specifically detected in wheat plants by PCR using primers TILf (5´-CAC AAG ACT ACG GAG GGG TG-3´) and TILr (5´-CTC CAA GCA ACC TTC TCT TTC-3´). DNAs from uninfected wheat, rye, barley and triticale were not amplified. Natural infection of control plants by other species of fungi as Alternaria spp., Erysiphe graminis and Fusarium spp. proved the specificity of the test because even in this case no unspecific products were formed. This method can be very useful both for seed producers and for state officers checking the seed quality.

N fertilization has a substantial influence on sunflower (Helianthus annuus L.) seed yield and quality. It was also well established that high-yielding sunflower hybrids had more N requirement than old cultivars such as open-pollinated ones. However, in Turkey, no sufficient information regarding the response of new developed oilseed sunflower hybrids to nitrogen fertilization under irrigated conditions. Therefore, a 2-year study was conducted to determine the effects of nitrogen application rates on the growth, yield, and yield components of two oilseed sunflower hybrids (AS-508 and Super 25) under irrigated conditions. In this study, all plant parameters were significantly influenced by applied nitrogen fertilizer rates. Yield response to nitrogen rates was positive and linear. Our research data indicated that under irrigated conditions N rate of 120 kg/ha was adequate for sunflower production in this region.

The present investigation was conducted to know the impact of bio-inoculants in low input field conditions on the magnitude and direction of gene effects and mean performance of some morphological and productivity traits in three wheat cultivars WH 147 (medium mineral input), WH 533 (drought tolerant), Raj 3077 (drought tolerant) and six generations namely P₁, P₂, F₁, F₂, BC₁ and BC₂ of three crosses i.e. WH 147 × WH 533, WH 533 × Raj 3077 and WH 147 × Raj 3077. The experiment was conducted in randomised block design with three replications and three treatments i.e. control (C, without inoculation), inoculation with arbuscular mycorrhiza fungi (AMF, Glomus fasciculatum), and AMF + Azotobacter chroococcum (Azc). Mineral fertilizer (80 kg N/ha + 40 kg P/ha + 18 kg ZnSO₄/ha) was applied in all the three treatments. The application of bio-inoculants, AMF and AMF + Azc had a positive effect on plant height, peduncle length, grain yield, biological yield and harvest index in various populations of all the crosses. However, in some of the generations the impact of bio-inoculants was insignificant. The joint scaling test revealed that additive-dominance gene effects were mainly operative in governing expression of peduncle length, tillers per plant, plant height, grains/spike, grain yield and all traits except days to flowering and harvest index in crosses WH 147 × WH 533 and WH 533 × Raj 3077. The application of bioinoculants influenced gene effects for days to flowering, days to maturity, flag leaf area, spike length, grains/spike, 1000 grain weight and harvest index where complex genetic interactions were changed to simple additive-dominance gene effects in the cross WH 147 × Raj 3077. Likewise, additive-dominance gene effects were altered and digenic interactions exhibited for days to maturity, flag leaf area in WH 147 × WH 533 and days to flowering, plant height, flag leaf area in WH 533 × Raj 3077. Flag leaf area and plant height were governed by additive gene effects while for days to maturity and 1000-grain weight both additive and dominance gene effect were important. Duplicate epistasis was important in all the three crosses for days to flowering and harvest index and in the cross WH 147 × Raj 3077 for grain weight grains per spike and flag leaf area.

Twelve carbonaceous materials were investigated for adsorption of Cd, Cu and Ag from water solutions. Before the adsorption experiments the chemical and structural characterization of all materials were made. The batch adsorption experiment was used. The kinetic of the adsorption process was very fast for the first five hours but very slow for approximately the next 65 hours. Nevertheless the maximum amount of metal removed was achieved during the first stage of about five hours. Biological materials (milled wood, bark, cork) exhibited a very low affinity for adsorption of metals. The best results were obtained for materials in an intermediate degree of carbonisation with a high content of oxygen rich functional groups. Although the highly carbonised materials exhibited low ability to adsorb copper or cadmium, their capacity to bind silver was very high.

The effect of droplet spectra on efficiency of contact and systemic herbicides was evaluated. As a model components were used: mixture of clethodim 240 g/l + surfactant (90% raps fluid, 10% polyetoxyl esters); bentazon 600 g/l and bentazon 480 g/l + Wettol LF 150 g/l. The effect of droplet spectra on Elytrigia repens (L.) Desv. was evaluated using systemic herbicide (clethodim 240 g/l + surfactant). No significant differences of the efficiency were observed between different droplet sizes at the treatments of mixture of clethodim + adjuvant between very different droplet size ranging from VMD = 193 µm to VMD = 929 µm. The effect of droplet spectra on Chenopodium album L. and Galium aparine L. was evaluated using contact herbicides (bentazon 600 g/l and bentazon 480 g/l + Wettol LF 150 g/l). Six droplet spectra, ranging from VMD = 183 µm to VMD = 911 µm, were used. The efficiency significantly increased with smaller droplet sizes. The worst results were achieved by droplet spectra of 586 µm and 911 µm for both bentazon 600 g/l and bentazon 480 g/l + Wettol LF 150 g/l. Effect of droplet spectra is more pronounced in contact compounds. Translocation of systemic compounds may be the main mechanism that nullifies the effect of the droplets size and lower leaf coverage.

This paper presents the results of the distribution of salinity characteristics (electrical conductivity and sodium adsorption ratio) of groundwater, and based on the results, it reports the evaluation of the salinity and sodicity hazards in the fluctuation processes of shallow mineralised groundwater, or in the processes if such groundwater is used for irrigation. The issue was studied for the soil-water environment in the south-east of the Danube Lowlands for the period 1991 to 1994. The measured data and data taken from archives were processed in the form of graphical attachments (appendixes, supplements, graphical documentation) - maps, by means of the kriging interpolation method. Groundwater in the area in question is classified as highly mineralised with a high hazard of salinisation of the subsurface soil environment. The average annual values of the electrical conductivity of groundwater ranged from 600 to 2100 µS/cm in the examined period. The sodium adsorption ratio values ranged from 1.7 to 22.0 and indicate low, medium to high sodium salinisation of the environment due to groundwater. The distribution of electrical conductivity and sodium adsorption ratio on the regional scale can serve as a reference basis for the evaluation of changes in the groundwater salinity after 1994.

Three maize inbred lines (Os86-39, Os89-35 and Os87-24) were grown in pots with Eutric Cambisol using 9 fertilisation variants (control 10 kg/ha Zn - on soil surface; 5 kg/ha - foliar application; 61 kg/ha P; 61 kg/ha P and 10 kg/ha Zn - on soil surface; 61 kg/ha P and 5 kg/ha Zn - foliar application; 183 kg/ha P; 183 kg/ha P and 10 kg/ha Zn - on soil surface; 183 kg/ha P and 5 kg/ha Zn - foliar application). The effects of phosphorus and zinc fertilisation on the dry matter yield, plant height, stalk diameter as well as phosphorus and zinc concentrations in ear-leaves were investigated. Significant differences were found between the lines in all parameters investigated except for phosphorus concentration. Line Os87-24 was characterised by the best results in the total biomass production. Zinc fertilisation decreased while phosphorus fertilisation increased total plant dry matter mass. Phosphorus fertilisation increased its concentration in the ear-leaves. Zinc fertilisation, especially foliar, resulted in Zn concentration increase in the ear-leaf of the lines investigated.

The influence of different fertilizer forms and rates on nitrogen, phosphorus and potassium contents, nitrate accumulation and yield in red head chicory (Cichorium intybus var. foliosum L.) was investigated. Field fertilization trials were set up at two localities inNorthwest Croatia in 1999 and 2000. Trials were laid out according to the Latin square scheme in five fertilization treatments: manure 5 kg/m2, three rates of complex mineral fertilizer NPK (5:20:30) - 50, 100 and 150 g/m2, and an unfertilized control variant. The results of investigations indicate that there were no significant differences between treatments in the plant nitrogen and phosphorus contents. Significant fluctuations of the chicory potassium content (3.27-4.75% K) depending on the fertilization variant were recorded only in 1999 while in 2000 all values (4.13-5.12% K) were uniform. Plant nitrate levels were influenced by weather conditions more significantly than by the form and rates of fertilizers. All the recorded values are within the limits tolerated for leafy vegetables. Comparing the trial years, yields were generally higher in 1999 (1.58-4.95 kg/m2) than in 2000 (0.40-2.70 kg/m2). No significant differences in yield were recorded between the application of stable manure and the lowest mineral fertilizer rate.

The effects of different tillage systems and dose reduction on the efficacy of triasulfuron & chlortoluron mixture in the post-emergence control of annual broad-leaved weeds in winter wheat and spring barley were studied on lessive pseudogley soil in north-eastern Croatiaduring 1997-2000. Total dry biomass production in untreated plots was significantly influenced by tillage and it was lowest in continuous mouldboard ploughing (99 kg/ha), medium and similar in mouldboard ploughing/disk harrowing alternating every second year and in chisel ploughing (218 kg/ha) whereas the biomass was highest in continuous disk harrowing (422 kg/ha). Thereby the proportion of annual broad-leaved weed biomass was 70, 63, and 28%, respectively. Chenopodium album L., Ambrosia artemisiifolia L., Ch. polyspermum L. and Polygonum aviculare L. are the most abundant annual weed species in all tillage treatments. One half and one quarter of the recommended rate decreased the control efficacy of total weed biomass by 12 and 19%, respectively in wheat and by 6 and 15%, respectively in barley compared to the highest dose but they still provided a very good biomass control of main annual weeds (94-96 percentage units). The efficacy of reduced herbicide doses in the control of annual broad-leaved weeds did not vary significantly between tillage treatments and growing seasons. Significant interaction with continuous disk harrowing tillage and one-quarter herbicide dose was detected in the last year of wheat trial when perennial weeds increased their biomass proportion 8 times compared to four years before.

Change in the community of epigeal spiders and harvestmen (Araneae, Opiliones) was studied in an experimental apple orchard for six consecutive years. Five plots were surveyed by pitfall traps. Four of the plots were young (1-4 years); one plot was older (15-20 years). The abundance of epigeal arachnids increased with the age on the young plots, while it was constant on the older plot. There were significantly more arachnids on the young plots than on the older one. In turn, the diversity was significantly lower on the young than on the older plots. Lycosidae, Phalangiidae and Tetra-gnathidae dominated the young plots. The older plots were richer in Agelenidae, Clubionidae, Dysderidae, Gnaphosidae, Linyphiidae, Pisauridae and Salticidae. Principal species of the young and older plots were identified using multivariate analysis.

The distribution of cadmium, lead and zinc in exchangeable, organic, and 2M HNO3-extractable fractions as well as the effect of heavy metal concentrations on soil microflora was investigated. Six sampling transects were chosen in theLitavkaRiveralluvium in 1999-2001. Concentrations of all metals increased with decreasing distance from the source of contamination. The concentrations of Cd and Zn in exchangeable fraction were higher than in organically bound fraction, a reverse trend was found in Pb speciation. All measured parameters of soil microbial activity were affected by heavy metal concentrations. The decrease in CFU was most significant in the case of oligotrophic bacteria and spore-forming bacteria. Significant inhibition of C-biomass occurred in soils highly contaminated by heavy metals. The Cbiomass:Cox ratio decreased with increasing soil pollution. Generally, the values of enzymatic activities were highest in the soil above the source of contamination and they were decreased as approaching the source of contamination. Our results demonstrate that several parameters of microbial activity could be used as good indicators of increasing concentrations of Cd, Pb, and Zn in soil.

Two methods were developed and tested for the measurement of the mowing machine material feed rate (based on the conditioner power input measured by a torque-meter, and/or on the material change in momentum measured by a curved impact plate). The measurements carried out in the year 2001 proved that a very good linear relationship existed between the conditioner power input, output frequency of the apparatus measuring the impact force by means of the impact plate, and the material feed rate through the mowing machine. The calculated R-Squared values were about 0.95. In the year 2002, the impacts of material and condition (parameters) changes on the mowing machine material feed rate measurement accuracy were measured under laboratory conditions. It was evident from the statistical evaluation that changing crop variety, crop maturity, and intensity of conditioning can have a statistically significant influence on the measurement based on the torque-meter. As concerns the impact plate measurement, it was found that it is not possible on the basis of our measurements to determine statistically the influence of the factors tested.

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.

Pea (Pisum sativum L.), sunflower (Helianthus annuus L.) and maize (Zea mays L.) plants were cultivated for 10 days in hydroponics at 1mM and 7mM nitrate or ammonium concentrations at regulated pH 6 and ambient CO2 level. Plant growth, content of total N and both ions in plant tissues, uptake of water and both N ions were evaluated, N uptake related to transpiration mass flow and to diffusion supply was calculated. Pea and sunflower preferred nitrate nutrition while maize plants used both N ions. The content of total N as well as of both N ions in plant tissues increased with N level with some exceptions. The uptake of both N ions related to transpiration mass flow was dependent on transpiration rate and N ion concentration. At a 1mM N concentration the uptake of N ions related to transpiration mass flow was low and reached in maize up to 16 times, in sunflower 11 times and in pea 2-3 times lower values in comparison with diffusion supply. At a 7mM N concentration N uptake in pea plants was totally supplied by transpiration mass flow, in sunflower plants the ratio of N supply related to transpiration mass flow amounted to 50% and in maize plants N supply through diffusion prevailed, amounting to 70-80%. These results explicate N starvation at low N supply that can intensify at elevated CO2 causing decreased stomatal diffusion.

The effect of phenylurea with reported cytokinin-like activities on seed germination, seedling growth, activities of antioxidant enzymes, polyphenol, peroxidase, indoleacetic acid oxidase, and total phenolic compounds, flavonoids was investigated in stressed barley seedlings. The application of phenylurea decreases the activity of peroxidase, indoleacetic acid oxidase and increases the activity of polyphenol oxidase with decrease in total phenolic compounds and flavonoids and consequent increase in growth rate. Saline (NaCl) stress in barley seedlings causes an increase in total phenolic compounds, flavonoids and enhancement of peroxidase and indoleacetic acid oxidase activities and consequent decrease in growth rate. The adverse effect of salt stress on germination, antioxidant enzymes, phenolic compounds, flavonoids can partially be rectified by phenylurea.

Rapeseed (Brassica napus L.) is an important alternate oilseed crop in eastern Anatolia, Turkey. No information on plant density for rapeseed is available in this region. Therefore a study was initiated to investigate the effects of spacings between rows and spacings within rows on the yield and agronomic characteristics of two genotypes of spring rapeseed (Tower and Lirawell) in Erzurum, eastern Anatolia, during 1994 and 1995. The effects of spacings between or within rows on the yield and yield components of Tower and Lirawell, two cultivars of Brassica napus L., were studied for 2 years inErzurum,Turkey. Rows were spaced at 15, 30 and45 cm. Spacings within rows were 5, 10 and15 cm. The results of this study suggested that seed yield was significantly affected by spacings between rows but not by spacings within rows, and that rape yields were higher at the narrow (15 cm) row spacing compared to the middle (30 cm) and wider (45 cm) spacings.

Three-year trials were conducted to study germination and emergence of prickly lettuce (Lactuca serriola L.) achenes, increments of shoot dry matter and susceptibility of the weed to selected herbicides. The germination rates of achenes at10°C (92%),20°C (97%) and30°C (95%) did not indicate any significant differences within 20 days from sowing. The highest percentage emergence of prickly lettuce achenes was determined after their sowing into a depth of1 mm. Differences from the variants of sowing onto the soil surface (0 mm), into a depth of 10 and20 mm were significant. There were no differences in the emergence rates from a depth of 10 and20 mm. The highest increments of shoot dry matter were observed when prickly lettuce plants were grown for 4-7 weeks after sowing at20°C. The effect of selected herbicides on prickly lettuce plants treated at the stage of 2-3 true leaves was evaluated on the basis of a change in the content of shoot dry matter. A significant decrease in dry matter against the control was recorded in all variants after herbicide application. The effect (expressed by a lower dry matter content) was significantly higher after the combination amidosulfuron + iodosulfuron-methyl + mefenpyr-diethyl (10 + 2.5 + 25 g/ha) was used than after the application of tribenuron (10.85 g/ha) and picolinafen + cyanazine (120 g + 480 h). The effect of amidosulfuron (22.5 g/ha) was significantly higher than in the variants treated with tribenuron, picloram + clopyralid (16.75 + 66.75 g/ha), clopyralid (90 g/ha) and picolinafen + cyanazine (150 + 600 g/ha). The best effects were produced by herbicides containing amidosulfuron and iodosulfuron as active ingredients.