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The soluble proteins extracted from the first leaf tissues of cultivated tetraploid (Triticum durum Desf., genome AB) and hexaploid (T. aestivum L., genome ABD) wheat species and their diploid wild progenitors [T. monococcum L. (A), Aegilops speltoides Tausch (B), and Aegilops tauschii Cosson (D)] exposed to 100 mmol/l NaCl stress were separated by two-dimensional (2D) gel electrophoresis. There was no newly synthesized protein in the NaCl treatment compared to the control treatment in all species. However, protein profiles showed some differences among species. Most of these proteins had acidic character; their isoelectric point (pI = pH - acidity of proteins) ranged between 5.1-6.9 and low-mol weight (LMW) between 20.3-30.6 kDa. Salt stress caused some proteins to increase or decrease. In the same MW and pI, 11 LMW and 3 intermediate-mol weight (IMW, 34.8-35.4 kDa) proteins increased and/or decreased in amounts were common between at least two species. The remarkable changes in Ae. speltoides were detected as decreases or losses in protein profiles. As a result of salt stress, all the remarkable changes in T. durum were detected as the increases in proteins. However, some proteins increased in T. aestivum, T. monococcum and Ae. tauschii. It is suggested that an increase in the amount of the proteins may lead to an increase in the tolerance mechanisms towards NaCl salinity of wheat species which has A and/or genome(s).

In long-term stationary experiments under different soil-climatic conditions, an influence of mineral and organic fertilization on yield of winter wheat, spring barley and potato tubers was evaluated. Statistically significantly lowest grain yields of winter wheat (4.00 t/ha) and spring barley (2.81 t/ha) were obtained in non-fertilized plots at all experimental sites. In the case of potatoes, the lowest yield of dry matter (5.71 t/ha) was recorded in the control plot, but the result was not statistically significant. The manure-fertilized plot gave the average yield of wheat higher by 30%, of barley by 22%. Application of sewage sludge resulted in wheat yield higher by 41% and barley yield higher by 26% over control. On average, application of sewage sludge and manure increased the yield of potatoes by 30% over control. The highest yield was obtained after application of mineral fertilizers; average yield increased by 59, 50 and 36% in winter wheat, spring barley and potatoes, respectively. No statistically significant differences among the plots with mineral fertilizers were observed. At different sites, the yield of studied crops varied; however, the effect of fertilization on yield increments was similar at all experimental sites except for Lukavec. It is the site with the lowest natural soil fertility, and it showed the highest effect of the applied fertilizers.

Defence reactions of desiccated cotyledonary somatic embryos and mature zygotic embryos of Abies numidica were tested by dual cultures with tester, fungus Phaeolus schweinitzii. Both types of embryos expressed defence reactions. Mutual comparisons of zygotic and somatic embryos showed important differences between defence reactions against mycelial growth towards these embryos. Greater defence reactions were observed in zygotic embryos relative to defence found in somatic embryos.

Arsenic (As) speciation transformation often accompanies adsorption-desorption when exogenous arsenide is poured into soil. Disregarding the speciation transformation when evaluating adsorption-desorption of As can greatly influence the experimental results. In this study, batch experiments were conducted, and the results indicated that exogenous monomethylarsonic acid (MMA) or dimethylarsinic acid (DMA) added to fluvo-aquic soil collected from agricultural area in Beijing of China, was completely converted into As(V) after cultivated for60 or 90 days. However, when exogenous As(V) was added to the soil, no speciation transformation of As(V) was observed. Furthermore, although the total As concentration, which was 6.55 or 11.55 mg/kg in aqueous extracts of the soil to which MMA or DMA had been added, respectively, remained stable after cultivated for 30 or 60 days, the As speciation transformation of MMA or DMA into As(V) in soil still occurred. Differences in As speciation can result in different fates and behaviors of As in soil, and As speciation transformation should be taken into account when evaluating the adsorption-desorption of As.

The effect of dimethylarsinic acid (DMA) on the growth of radish and the content of As compounds in roots and leaves of the radish were investigated. Radish was grown in pots in three soils (Fluvisols, Chernozems and Luvisols) amended with 20 mg As/kg of soil in form of DMA. Behavior and transformations of DMA in the soils differed depending on the individual soil type. In the first season, plants grew up at Luvisols only. In the second season the plants were able to grow at Luvisols and Chernozems, too. The roots and leaves of radish from Luvisols had DMA as the dominant arsenic compound present (~ 90% in the extract) in the first season. In the roots of the subsequently growing radish DMA accounted for 20% and arsenite for most of the total arsenic in the extract. In the leaves of the second-crop of radish DMA remained the dominant arsenic compound (~ 60% in the extract) with arsenate and arsenite for the remaining 40%. Roots and leaves of radish grown in Chernozems and Luvisols had a similar pattern of arsenic compounds. Soil properties significantly affected transformation of As species in the soils. At Fluvisols was the lowest As immobilization and about 98% was found as DMA after two years of experiments in the other two soils was higher As immobilization and DMA was recovered to inorganic As (V) - 31% in Luvisols and 78% in Chernozems.

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.

Daily outputs from eight evapotranspiration models were tested against reference evapotranspiration (ETo) data computed by FAO56PM to assess the accuracy of each model in estimating ETo. Models were compared at eight stations across Jordan. Results show that Hargreaves modified models were the best in light of mean biased error (MBE), root mean square error (RMSE) and mean absolute error (MAE). The MBE, RMSE, and MAE values ranged from -1.47 to 0.81, 3.87 to 1.14 and 0.87 to 3.15 mm/day for HarM1, and from -1.45 to 0.89, 1.08 to 3.91, and 0.85 to 3.16 mm/day for HarM2, respectively, which would make it the best models in light of the MBE, RMSE and MAE ranging from -6.18 to 2.79, 6.90 to 1.08 and 4.74 to 0.85 mm/day for all models and stations. Comparisons were also made using three composite regions: countrywide, semiarid, and arid regions. In conclusion, local calibration is needed for the whole models or the linear regression can be used to calculate the ETo.

A field plot (100 m × 50 m) was chosen in a karst depression area of Huanjiang County, Guangxi Province of southwest China, with the aim of characterizing the variability and patterns of upper 15 cm soil moisture. Soil moisture content was measured at 5 m intervals by gravimetric method during dry and rainy seasons in 2005. Results indicated that the surface soil moisture presented a strong spatial dependence at the sampling times in the field scale. The variability of soil moisture by CV values and sill decreased with the increasing mean field soil moisture content either in dry or rainy season. In the dry season, mean soil moisture had a little influence on the sill owing to the previous tillage. But, in the rainy season, a heavy rain event could decrease the variability of soil moisture. The anisotropy characteristics were found that the variance was lower in 0° direction than that in 90° direction based on the northeast axis, and the range had opposite trend except for the sampling on March 15, 2005. The mosaic patterns of soil moisture exhibited the variability and its anisotropy visually. The rainfall (mean soil moisture), topography and micro-relief (rock outcrops) had important influence on the variability of soil moisture. To better understand the variability of soil moisture in the karst depression area, more soil samples should be required in the dry season and in a field with more rock outcrops.

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.

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.

There is little experimental evidence about the functional significance of arbuscular mycorrhizal fungi (AMF) colonization in providing nutrients for lowland rice. This study was undertaken to examine whether growth and nutrient deficiencies may affect plants benefit from AMF inoculation. Two contrasting rice (Oryza sativa L.) genotypes and two AMF species (Glomus mosseae and G. intraradices) were used in this experiment. Under P starvation, P uptake in the genotype tolerant to P deficiency (Fajr), declined significantly up to 36% (P < 0.05) in response to AMF inoculation, while it enhanced by about 70% (P < 0.01) in susceptible genotype (Shafagh). Under Zn starvation, Zn uptake of Zn-efficient genotype (Shafagh) increased by about 2 fold (P < 0.01), but a reduction of 52% (P < 0.05) was observed in the Zn-inefficient genotype (Fajr) upon mycorrhization. Greater genotypic differences were observed for -P-Zn plants. Our results imply that genotypic difference in responsiveness to inoculation with AMF is attributable to different contribution of mechanisms for increased nutrient uptake in mycorrhizal plants depending on nutrient, nutritional status and nutrient efficiency of genotypes.

A field experiment was conducted to illustrate the different degree and dynamics of microbial community structure and function in the rhizosphere across four growing stages (before plantation and three growth stages) using a combination of biochemical (enzyme assay and microbial biomass carbon) and molecular approaches of qPCR and PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis). Rice plant cultivation promoted higher enzyme activities (invertase and urease), microbial biomass carbon (C_mic), bacterial (16S rRNA) and fungal (ITS rRNA) genes abundances in the rhizosphere compared to unplanted soil. Principal component analyses of PCR-DGGE profile also revealed that structures of bacterial and fungal communities of rice planted soil were well distinct from unplanted soil. Moreover, enzyme activities showed a significant positive correlation with the total microbial biomass in the rhizosphere throughout growth stages of rice plant. Relative fungal: bacterial ratios were significantly higher in rice planted soil compared to unplanted soil, suggesting rice plantation enhanced the fungal community in the rice rhizosphere environment. These results further suggest a significant linkage between the microbial community dynamics and function in the rhizosphere associated with rice plant over time.

Improvement in leaf hydraulics is directly related to the improvement of plant tolerance to drought stress. Therefore, a field and pot experiment was carried out to determine the type of genetic variability and selection of parental types on the basis of combining ability for leaf hydraulics. Genotypes showed similar performance in both experiments; higher values were shown by drought tolerant genotypes in all traits except for osmotic potential, which drought tolerant genotypes maintained lower. Osmotic adjustment in pot experiment showed the highest magnitude of additive type of genetic variability. Female showed a higher and significant contribution of general combining ability effects as compared to male; it suggests that within genotypes female rather than male mostly contribute for additive genes. AMES-10103 showed the highest general combining ability effects for traits such as turgor pressure and osmotic adjustment.

The heavy metal contents and their bioavailability were monitored in soils of Central Spiš region of SR. This area belongs to long term contaminated and hygienically loaded areas. Soil contamination by heavy metals is caused especially by ore mining, processing and treatment. Soil samples from the Central Spiš contained higher proportions of mobile forms which corresponded to the following sequence Pb > Zn > Cu, while for mobilizable forms the sequence of investigated metals was as follows: Cu > Zn > Pb. Soil pH is one of the parameters that affect significantly the share of bioavailable forms of metals. Higher proportions of mobile fractions of metals were detected in samples taken from soils with acidic pH. Statistical processing confirmed a relationship between the percentage share of lead and zinc in the mobile form and the level of pH/KCl, which was significant for Zn: r = -0.53. The relationships for lead and copper were insignificant.

Investigations were carried out at the experimental field of the Faculty of Agriculture in Zagreb in the growing seasons 2008/2009 and 2009/2010 with the aim to determine the influence of seeding rate and fungicide treatment upon the yield and yield components of spelt (Triticum spelta L.). The trial included two spelt cultivars: Nirvana and Ostro, three seeding rates: 200, 300, and 400 germinated seeds/m2, and a fungicide treatment (tebuconazole). Cultivar Nirvana produced a significantly higher grain yield in both trial years, higher number of spikelets per spike, higher grain number and mass per spike. Cultivar Ostro had a significantly higher grain crude proteins content, higher 1000 grain weight, and also a higher number of sterile spikelets per spike. No significant effect of seeding rate on grain yield was determined while the fungicide treatment had a significant effect on grain yield only in the warmer year 2008/2009.

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

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

Most of the works published since the beginning of the 20^th century have brought interesting results about beneficial effects of titanium (Ti) on plants, but much less is known about its phytotoxic effects at higher doses. Here we demonstrate the influence of Mg treatment on the phytotoxic effects of Ti. Mg, Ti + Mg and two different concentrations of Ti leaf sprays were applied on oats (Avena sativa L. cv. Zlaťák) grown on three different soil types (Fluvisol, Luvisol and Chernozem). Physiological parameters of oats as well as some essential elements contents were analyzed. The foliar applications of Ti caused significant toxic manifestations on oats at ≥ 10 mg/kg concentrations. Mg partially ammeliorates these toxic effects if applied together with Ti. The effect was strong on Fluvisol, but weaker on Chernozem and Luvisol. Ti effects are more significant the further the soil is from the nutritional optimum of the plants. This is most evident in the case of Fluvisol, which is deficient in Mg, Fe, Mn, and Zn. It seems that Ti possesses a generally equalizing effect on the elements content in the plant.

In 2004-2006 an influence of various plantation row spacings on yield and quality of hops was observed in field trials. A hybrid variety Agnus was selected for this purpose. The common space between the rows remained (300 cm). The tested distances of individual hop plants within each row amounted to 114 and 133 cm. We compared the standard kind of four trained bines from each hill with a new one (five bines per hill). The yield of hops was the highest if row spacing 300 × 114 cm was used (2.80 tons of dry hops per hectare). If spacing 300 × 133 cm was tested, the yield amounted to 2.69 t/ha. The lowest yield of hops was obtained when the common row spacing 300 × 100 cm was used (2.58 t/ha). Yield increase in the plots with new spacing was at the limit of significance. Weather was the main factor influencing hop crop in 2006. Statistically significant differences in the yield of hop cones were proved in the year with very good growing conditions (2005) as well as in the year with relatively bad weather conditions (2006). If average conditions prevailed (2004) no significant differences between experimental and control plots were observed. Alpha acid contents were the highest (12.45%) in the perspective row spacing (300 × 114 cm); a slight decrease was found when the spacing of 300 × 133 cm was used (11.92%). In the case of the control variant with the common row spacing 300 × 100 cm, alpha acid contents amounted to 12.29%.

Net N mineralization rate (NMR), net N consumption rate (NCR), microbial biomass carbon (MBC) and nitrogen (MBN), potentially mineralizable N (PMN) and mineral N (N-NH⁺₄ and N-NO^-₃) were measured in paddy soil at five growth stages of rice to determine the effect of long-term fertilization in subtropical China. The studied long-term treatments included CK (no fertilization), N, NP, NPK and NPK + OM (NPK plus organic manure). The NPK + OM treatment gave the highest values of the measured variables among all treatments. There was no significant difference in other treatments except for mineral N and PMN at early growth stages. All these variables were generally highest at transplanting stage as two thirds of fertilization was applied as basal fertilizers and the rice uptake was low. Then they decreased or leveled off with the rice growth stages except for MN in all treatments. Stepwise regression revealed that NMR was significantly correlated with MBC and N-NH⁺₄ (R² = 0.954, P < 0.01) at all rice growth stages. So, mineral plus manure fertilizer application and more mineral fertilizer as topdressing were recommended in subtropical paddy soil.

Microbial biomass and community catabolic diversities at three depths (0-10 cm, 20-30 cm, and 40-50 cm) in Chinese Mollisols as influenced by long-term managements of natural restoration, cropping and bare fallow were investigated. Microbial biomass was estimated from chloroform fumigation-extraction and substrate-induced respiration (SIR), and catabolic diversity was determined by using Biolog® EcoPlate. Experimental results showed that microbial biomass significantly declined with soil depth in the treatments of restoration and cropping, and not in the treatment of bare fallow, where the microbial biomass had a positive relationship with the total soil C content. The inspections into the catabolic capability of the microbial community at the same soil depth showed that the treatment of natural restoration had a relatively stronger metabolic ability than the cropping and bare fallow treatments. Shannon"s diversity index, substrate richness and substrate evenness calculated from the Biolog data were higher in the treatments of natural restoration and cropping than the bare fallow treatment with the same soil depth, and with the highest values in the top soil. Principal component analysis indicated that the catabolic profiles not only varied with the soil depth in each treatment, but also differed in the three treatments within the same soil depth. The catabolic profiles of the three treatments were similar to each other in the soil depth of 0-10 cm and distinctly different in the soil depths of 20-30 cm and 40-50 cm. These results suggest that it was microbial biomass rather than community function that was influenced by the different soil management in the topsoil (0-10 cm); in the relative depths, the soil microbial community function was more easily influenced than microbial biomass.

The present study was undertaken to quantify changes in the status of soil nutrients, their depletion and build-up after continuous long intensive cropping for last 36 years in a permanent manorial trial which has been in progress since 1972 in an alfisol of western Himalayas. The rotation was maize-wheat which included various combinations of N, P, K, Zn and FYM (farmyard manure). Continuous cultivation influenced pH, OC (organic carbon), available N (nitrogen), P (phosphorus) and K (potassium). An increase in the status of organic carbon was observed in 100% NPK + FYM treatments for more than three decades from initial value of 7.9 to 12.0 g/kg. The use of either FYM or lime alongwith 100% NPK sustained crop productivity or improved nutrient status. However, imbalanced use of nutrients i.e. NP or N alone is adversely affecting the fertility of soil by aggravating the problem of soil acidity. Application of S free P fertilizer DAP (diammonium phosphate) drastically reduced the yield of both the crops. Thus, continuous use of balanced fertilizers is necessary for sustaining soil fertility and productivity of crops.

In the years 2004 and 2005 precise field trials were performed with the aim to evaluate the effect of variety, year of cultivation, N, P, K and Mg fertilization, and the cover with white propylene fibre Paegas-Agro UV 17 on the total carotenoid content (TC) in potato tubers. TC was determined by absorption UV-VIS spectrophotometry and obtained results were statistically evaluated (ANOVA and MANOVA variance analyses, Scheffe's test). Statistically significant differences (P = 0.05) in the ability of varieties to synthesize carotenoids were found (Karin, Agria and Marabel with high TC × Impala and Saturna with low TC) and also the year of cultivation significantly affected TC (5.8 mg/kg fw in 2004, 20.9 mg/kg fw in 2005). The effect of fertilization with N, P, K and Mg on TC in potatoes did not show any significant effect; however significant differences were observed among varieties. The effect of white polypropylene fibre in two early potato varieties (Adora and Impala) during three dates of harvest on TC in potato tubers was not significant. Contrariwise, statistically significant effects on TC were reported in the case of potato tubers maturity, year of cultivation and potato variety.

This work presents the results of a survey that studied simulated plant browsing by herbivores. In 2004-2006, winter wheat, spring barley, and maize field trials were founded in order to monitor the impact of different levels of defoliation (leaf area reduction) on the yield and grain quality. The defoliation was carried out by means of mechanical removal of plant parts in the early growth stages. Selected qualitative parameters were determined in the harvested grain of wheat and barley. Statistically significant influence of leaf area reduction (LAR) on grain yield (decrease by 4-14%) was found only in maize in 2004. No statistically significant influence of the leaf area reduction on thousand grain weight (TGW) was found in any of the studied crops. The leaf area reduction in barley did not affect grain characteristics; however, it had a statistically significant influence on the quality of wheat grain. Moreover, wheat reduction statistically significantly increased the falling number (by 29-39 s) and decreased SDS test values (by 8-9 ml).

Sustainable land management requires that water and matter (nutrients and base cations) are efficiently recycled within ecosystems so that irreversible losses of matter from topsoils are minimised. Matter losses are connected to water flow. The division of water into evapotranspiration that is loss-free, and seepage to groundwater or surface water flow that both carry material losses, is decisive in determining total losses of dissolved matter in a given catchment. Investigations of areal matter losses confirmed the instrumental role of vegetation cover. Areal matter losses measured in agricultural catchments in Germany were on average between 1-1.5 tons of dissolved matter per ha per year, i.e. some 50 to 100 times higher than those from unmanaged land in a virgin forest. Such high losses continuously reduce soil fertility and can hardly be compensated by fertilisation. Some suggestions on how to achieve sustainable management of agricultural land and maintain high soil fertility are presented - the priority is to close water and matter cycles through the incorporation of more natural vegetation cover into our landscapes and to restore the energy-dissipative properties of ecosystems.

A study was conducted on the effect of two single practices, including soil tillage and returning straw to soil, and their interaction on soil porosity of maize-wheat cropping system. Field experiments involved four tillage practices, including conventional tillage (C), zero-tillage (Z), harrow-tillage (H) and subsoil-tillage (S), with straw absent (A) or straw present (P). Total porosity, capillary porosity and non-capillary porosity of soil were investigated. The results showed that the soil total porosity of 0-10 soil layer was mostly affected; conventional tillage can increase the capillary porosity of soil, but the non-capillary porosity of S was the highest. Returning of straw can increase the porosity of soil. Through the analysis of affecting force, it can be concluded that interaction of soil tillage and straw is the most important factor to soil porosity, while the controlling factor to non-capillary porosity was soil tillage treatment.

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

Soil samples (from Czech and German long-term field experiments) were used to estimate different soil phosphorus (P) fractions. More than 200 topsoil (0-30 cm) samples from different fertilizing treatments were taken. These were analyzed for P in soil solution (P_CaCl2) [0.01M CaCl₂ extract], exchangeable sorbed P (P_ex) [anion exchange (AE) membranes] and bioavailable P [Doppel-Lactat and Mehlich 3 (P_DL and P_M3)]. Other fractions analyzed were total inorganic (P_in), total (P_M-tot) and organic (P_org) P [fractionation after Marks], P sorbed on Fe and Al (P_FeAl) [fractionation after Schwertmann] and residual P (P_ar) [aqua regia extract]. Comparison of medians appeared to be better for evaluating extraction abilities. Phosphorus fractions were in the following order: (P_ar = 100%); P_CaCl2 (0.2%) < P_ex (9%) < P_DL (10%) < P_M3 (16%) < P_in (24%) < P_org (37%) < P_FeAl (55%) < P_M-tot (59%). Low amounts of P_in, P_org and P_M-tot did not verify the applicability of the Marks' fractionation for the set of studied soils. Close correlations at P ≤ 0.001 were found for all methods for estimating the fractions of bioavailable phosphates (P_CaCl2, P_ex, P_DL and P_M3). Statistically significant relations were observed between P_in with P_ar, P_M-tot and P_FeAl.

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

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.