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In Brazil savanna type of soils presents problems with phosphorus content. The selection and identification of maize genotypes to such environments is a high priority of Brazilian research. The purpose of this paper was to evaluate, in soils with different P concentrations, the dry mass attributes and characteristics of root morphology in eight maize lines with different genetic background and origins of the Breeding Program of the National Research Center for Maize and Sorghum. The experiment was carried out in plots prepared with two levels of phosphorus: high phosphorus (HP) and low phosphorus (LP). The experimental design was randomized blocks with three replications. The evaluation of the characteristics of the shoots and the root system morphology was performed 21 days after sowing. The WinRhizo program of images analysis was used for the root morphology. There were no differences between the phosphorus levels for the dry mass attributes. However, when we compared P levels, root morphology of L13.1.2 strain performed the highest surface area (SA) and total root length (RL), length of thin (TRL) and very thin (VTRL) roots in low P concentration. The root systems digital images analysis techniques allowed efficient discrimination of maize genotypes in environments with low P levels.

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.

Between 2002 and 2004 the evaluation method of resistance to common scab was tested on potato genetic resources. The resistance of potato tubers to common scab was evaluated in the greenhouse provocation tests with planting in naturally infested soil. The test was evaluated on the tubers of 26 varieties and hybrids of Solanum tuberosum derived from a potato genetic resource collection. Ten tubers of each sample were individually planted into three-liter pots containing infested soil. Analysis of variance confirmed significant differences among individual varieties and hybrids as well as among the years. A rating scale for the evaluation of resistance to common scab was designed. The genotypes ranked into scores 7 (high resistance) to 9 (very high resistance); on the new scale they could be considered perspective genetic resources in breeding for improvement of the level of this character. The evaluated set consisted of genotypes: Samantana, Karin, Monika, Impala, Santé, Annabelle, YP 94-067, YP 91-123, BEE J 85, Viola, and Granola.

This paper addressed the spatial distribution characteristics of organic matter, total nitrogen, extractable phosphorus and extractable potassium in agricultural soils of Northeast China. The related factors were explored using geostatistics and geographic information systems. The results showed that the log-transformed data of the four soil nutrients followed a normal distribution. Soil extractable phosphorus had a higher coefficient of variation. The experimental variogram of the log-transformed data of soil organic matter, total nitrogen and extractable phosphorus was fitted with an exponential model, while soil extractable potassium was fitted to a spherical model. Soil samples from smaller slope gradients had higher organic matter and total nitrogen. Soil type affected the four soil nutrients significantly. Soil samples from dry farming land had significantly higher total nitrogen and extractable potassium than soil from paddy fields, while the contrary was found for extractable phosphorus. Along the Yinma River, soil samples from the western part have statistically higher values for organic matter, total nitrogen and extractable potassium than those collected from the eastern part.

Dynamics of crop growth and photosynthesis are two main processes that are of major importance for adaptation of plants to their environment. Two experiments were carried out during 2005 and 2006 with sun and shaded barley plants. The results showed that leaf area increased with leaf position on the main stem up to leaf position 5 for sun and leaf position 6 for shaded plants, and then declined towards flag leaves. Air temperature affected leaf appearance, mainly at the beginning of the growing season. A positive correlation between leaf expansion duration (LED) and accumulated temperature sum was measured for both variants, LED linearly increased with temperature sum. Leaf expansion rate (LER) showed a similar dependence on accumulated air temperatures in both light variants. A strong relation was found between soil temperature and LER for the first four leaves of the main stem of shaded plants in 2006. In shaded environment the higher LER was associated with lower accumulated irradiance sum when light restriction supported an increase of leaf elongation and final leaf length.

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 monitoring was carried on in the years 1996-2000 in the polyfactorial P-A field trial in Lukavec, Pelhřimov district. The given locality is characterized by low fertility sandy-loamy cambisoils, by long-term average annual rainfall of 653 mm, by average annual temperature of 7°C and its altitude is 620 m. The field trial included different organic fertilizations; graduate N-doses, different soil tillage as well as different forecrops. It manifested in this group of field trials that the forecrop value of red clover and dung manured potatoes before winter wheat was practically the same in the given locality. The optimal N dose for potato yields was about 80 kg N.ha^-1. In oats the yields after red clover with using the Horsch system in spring were significantly lower than after embedding of red clover in autumn. In cereals, graduated N doses increased the numbers of ears (panicles) per m2, but the mass of 1000 grains often decreased. In addition, N content in grain and straw increased with N doses, while pH annually decreased by 0.1 to 0.4.

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 seeds of two medicinal plants, namely Chamomilla recutita (Babong) and Origanum majorana (Bardaqoush) were subjected to germination in different NaCl concentrations, polyamines (putrescine, spermidine, spermine) and to combination of both. The results revealed that the growth alterations induced by NaCl were alleviated by various levels of polyamines. The organic solutes of both plant seedlings exhibited somewhat variable responses to various salinity levels or polyamines treatments and in combination of both treatments. Putrescine in Ch. recutita seedlings was more effective in alleviating the stress effects of salinization than spermidine and spermine, while in O. majorana seedlings spermidine was more effective. Generally, the degree of stimulation differed according to the type, concentration of the additive used and the type of the plant tested.

Hop purchasers impose still higher requirements on the quality of the final product, which is why hop granules have to be divested of all possible impurities. One of the places that are most at risk from the given point of view is the making of hop strings and the way they are attached to the hop-field supporting structure. Commonly used hop string attachments very often remain on the supporting structure after the harvest, spontaneously loosen in the following years, penetrate into the post-harvest processing stage of the technological procedure and negatively influence the output quality of the hops. The article summarizes the results of field experiments done during the pull-down of hop vines using a common hop string, but with various attachments with the aim of looking for the most suitable treatment which would exclude the risk of impurities penetrating from this stage of the technological procedure into the final product. The measurement carried out shows that so far the most advantageous treatment is hop string with simple attachment formed by twine 12 500. Breakage of hop strings occurred in 93% in twine, while with the rest of the vines only in wire.

Actual yields of maize harvested by farmers are at level much below attainable yield potential of currently cultivated varieties. Among many growth factors zinc was recognized as one of main limiting factors of maize crop growth and yielding. This hypothesis has been verified within a three-year field study, where zinc fertilizer was applied to maize plants at the 5^th leaf stage. Maize crop responded significantly to zinc foliar application in two of three years of study. The optimal rate of zinc foliar spray for achieving significant grain yield response was in the range from 1.0 to 1.5 kg Zn/ha. Grain yield increase was circa 18% (mean of three years) as compared to the treatment fertilized only with NPK. Plants fertilized with 1.0 kg Zn/ha significantly increased both total N uptake and grain yield. Yield forming effect of zinc fertilizer revealed via improvement of yield structure elements. The number of kernels per plant showed the highest response (+17.8% as compared to the NPK plot) and simultaneously the highest dependence on N uptake (R² = 0.79). For this particular zinc treatment, however, the length of cob can also be applied as a component of yield structure significantly shaping the final grain yield.

The aim of the paper was to contribute to the acquisition of background data for the specification of safe boron levels in soils in relation to diagnostics by multi-nutrient soil tests and to CEC (cation exchange capacity) value of soil, pH and soil organic matter. The research was conducted on 24 soils. Sorption was determined after 97 days from the application of B at the rates of 0, 1, 2.5, 5 mg B/kg in H₃BO₃. The closest regression of B-sorption was with the CEC value of soil in NH₄-acetate and water tests and it increased with the increasing application of B (regression at a rate of 5 ppm B; NH₄-acetate: linear R

Plant root and shoot dry weight, leaf relative water content (LRWC) and chlorophyll content were reduced by 30%, 21%, 15%, 34%, respectively, at 40mM NaCl as compared to non-salt stress conditions. However, membrane permeability (MP) of plant increased (85.0%) with increasing salinity. Foliar nutrient application (FNA) alleviated deleterious effects of salinity stress on growth and this effect was statistically significant. The highest alleviation effect of FNA at 40mM salinity stress was observed in the case of 10mM foliar KNO₃ and Ca(NO₃)₂ application, resulting in increase in plant root dry weight (50%), shoot dry weight (50%), LRWC (8.2%) and MP decrease (27.4%) at 40mM NaCl. Phosphorus, Fe and Zn contents in shoots and roots of plants also increased with FNA treatments, but they were still much lower than those of non-salt stress treatment. Sulphur, P, Fe and Zn contents of shoots reached similar values as in non-salt stress treatment when KNO₃ was applied, whereas Fe, Mn, Zn, and Cu contents of roots reached the values of non-salt stress treatment when Ca(NO₃)₂ was applied.

Sulfur (S) regarded as the fourth key element is mainly taken by the plant roots. However, some plants can also absorb atmospheric sulfides, which may be of great importance for ameliorating the environment and for farming as a green organic S fertilizer used to balance insufficient soil S content for intensive cultivation in China; H₂S and mainly SO₂ are emitted to air as a result of the rapid industrialized and economic development. Globe amaranth (Gomphrena globosa L.) might be one of the plants that can use atmospheric sulfides for its growth. Therefore the effects of sulfate deprivation from root on its growth, S status and other elements concentration under hydroponic culture were explored firstly. Based on measurements of plant growth, biomass, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), S, iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), boron (B), and molybdenum (Mo) concentration, the results showed that S concentration in flower, shoot and root of plant without root sulfate supplied was increased with plant growth and development, symptoms of S deficiency disappeared and other elements concentration in plant tended to be nearly the same as the root sulfate-supplied plants. The interesting results might imply that globe amaranth may be able to live on the atmospheric sulfides as sulfur source.

In 1999-2001 sulfur and sulfate concentrations were studied in expanded young leaves of rapes of the line variety Lirajet and hybrid variety Pronto at the onset of stem elongation (DC 30), flowering (DC 64) and early maturity (DC 70) in different localities of the Czech Republic. Except the S-deficient site the concentration of total sulfur and sulfates in leaves considerably increased in higher growth stages. A less steep increase in S concentration in leaves was associated with rather humid growing season, especially with April precipitation. Great time variations in sulfur concentrations in leaves signal a possibility of diagnostic misinterpretation of plant analysis without exact definition of growth stage. The shape of trend of variations in S concentration in leaves indicates the S nutritive state of the site and the intensity of upward transport of sulfates with soil moisture in the crop nutrition with sulfur. Good yields of rapeseed were connected with minimum concentration of total sulfur 0.5%, and sulfate sulfur 0.2% in leaf dry matter at DC 30. The proportion of sulfates in total concentration of sulfur in rape leaves ranged from 30 to 60% at the onset of stem extension and it increased in higher phenophases. At flowering, sulfates accounted for 80% and more at sites where sulfate uptake from the soil environment was not problematic. Besides the S-soil test, the results of investigations indicate the importance of CEC value of soil for the preventive diagnosis of S-nutrient state of the site.

Simple balance of Cd input by different treatments and removal by agricultural crops was investigated in an ongoing precise long-term field experiment with application of sewage sludge (SS), farmyard manure (FYM), and mineral fertilizers (NPK). Potatoes, wheat and barley were grown in a rotation at 4 experimental sites of the Czech Republic with the aim to assess the risk of Cd accumulation in soil and plants under different soil and climate conditions. The results showed significant differences in Cd content of the input materials used, and in Cd inputs to soils under different fertilization managements. Three applications of sewage sludge during 1996-2005 resulted in total addition of 110 g Cd/ha into soil, which was by one order of magnitude higher than Cd addition in FYM or NPK treatments. From the total amount of sludge-borne Cd, only small portion was removed by harvests of crops (approximately 3.5%). Soil conditions significantly affected Cd input-removal balance. The highest Cd removals were obtained on soils with the lowest pH. The highest Cd removal was achieved by potato tubers followed by wheat and barley plants. The results showed that the risk of Cd accumulation in soils is high, especially with repeated sludge applications.

Soil water content under no fertilizer (NF), fertilizer (F) (N:30; P₂O₅: 45 kg/ha), and fertilizer plus pig manure (FO) (N:30; P₂O₅: 45 kg/ha; pig manure 15 000 kg/ha in 2003; and 30 000 kg/ha in 2004 and 2005) treatments was measured using neutron probe instrument for a period three years in a long term field experiment in order to investigate the impact of different fertilization treatments on Haploborolls soil water content. Fertilization had significant effects on the soil water content. FO treatment had greater soil water content in 10 cm depth than F treatment with average 9.9% increase (P < 0.05) but lower than NF treatment; however, in the depth from 30 to 90 cm, there was no water content difference between F and FO treatments. Treatment with organic amendments reduced total soil water content on the long term experiment basis. Across the three years, no fertilizer treatment had total soil water content higher by 1.2% and 3.1% than fertilizer treatment and fertilizer plus pig manure treatment within 10 to 210 cm soil profile in most of the months, respectively.

Nitric oxide (NO) is a gaseous diatomic molecule with a wide variety of physiological and pathological implications in plants. Presence of unpaired electron in its molecular orbital makes it highly reactive; it can react directly with metal complexes, radicals, DNA, proteins, lipids and other biomolecules. Nitric oxide (NO) and reactive oxygen species (ROS) are known to play essential role in a number of important plant physiological processes. This manuscript reviews the role of NO on these processes during various biotic and abiotic stresses.

Citrulline has been recently shown to behave as a novel compatible solute in the Citrullus lanatus (Cucurbitaceae) growing under desert conditions. In the present study we have investigated some aspects of the relationship which might occur in leaves of melon seedlings, also known to produce citrulline, between the capacity to accumulate this ureido amino acid and salt tolerance. With this end in view, salt-induced changes at the citrulline level have been compared in two melon genotypes exhibiting contrasted abilities to withstand the damaging effects of high salinity. Progressive salinization of the growing solution occurred at 23 days after sowing. The final 250 mmol/l external NaCl concentration was reached within 5 days and further maintained for 16 days. In response to this treatment, it was found that the citrulline amount increased in fully expanded leaves of both genotypes according to different kinetics. The salt tolerant genotype Midyat was induced to accumulate citrulline 4 days before the salt sensitive Yuva and as a consequence the final amount of this amino acid was twice higher in the former than in the latter. Compared with citrulline, the free proline level was found to be relatively low and the changes induced in response to the salt treatment exhibited different trends according to the genotypes under study. Thus at the end of the treatment mature leaves of the salt sensitive Yuva contained higher amount of proline than those of Midyat. The changes in the calculated molar ratio between citrulline and free proline suggested that salt tolerance might be associated with high values for this ratio and vice et versa for sensitivity. The interest of citrulline as a biochemical marker for salt tolerance of melon genotypes is discussed.

This paper evaluates the effect of partial root zone drying (PRD) and deficit irrigation (DI) strategies on yield and water use efficiency of the drip-irrigated corn on clay soils under the Mediterranean climatic conditions in Southern Turkey. Four deficit (PRD-100; PRD-75; PRD-50; and DI-50) and one full irrigation (FI) strategies based on cumulative evaporation (E _pan) from class A pan at 7-day interval were studied. Full (FI) and deficit irrigation (DI-50) treatments received 100 and 50% of E_pan, respectively. PRD-100, PRD-75 and PRD-50 received 100, 75 and 50% E_pan value, respectively. The highest water use was observed in FI as 677 mm, the lowest was found in PRD-50 as 375 mm. PRD-100 and DI-50 resulted in similar water use (438 and 445 mm). The maximum grain yield was obtained from the FI as 10.40 t/ha, while DI-50 and PRD-100 resulted in similar grain yields of 7.72 and 7.74 t/ha, respectively. There was a significant difference among the treatments with respect to grain yields (P < 0.01). The highest water use efficiency (WUE) was found in PRD-100 as 1.77 kg/m³, and the lowest one was found in FI as 1.54 kg/m³.

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.

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.

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).

We performed 28-day mesophilic fermentation of a mixture of pig slurry and primary (raw) sludge from the sedimentation stage of a wastewater treatment plant at a 1:1 ratio. The components and the original and fermented mixture of slurry and sludge were subjected to acid hydrolysis. Dry matter of the solid phase of both components and both mixtures was incubated with sandy-loamy Cambisol at a weight ratio 3:1 at 25°C for 20 weeks; in 14-day intervals lipids, crude protein, hemicelluloses, cellulose, lignin, total nitrogen and hot-water-insoluble solids were determined. Changes in ion-exchange and buffering capacity of the test materials were recorded. Labile organic matters were determined after 20 weeks of incubation. Liquid fractions of both components and their mixtures were analysed before and after anaerobic fermentation. It was concluded that beneficial effects of wastes as fertilisers from anaerobic digestion could be attributed to their liquid fraction. After anaerobic digestion the solid fraction of these wastes has relatively increased ion exchange capacity as well as buffering capacity but it is very stable, hardly degradable organic matter, and therefore it cannot play the role of organic matter in soil. This is the reason why it should not be considered as an organic fertiliser.

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.

An alum-based drinking water treatment residue (DWTR) is the by-product from the production of potable water. Land application of DWTR has received a considerable attention for its potential as a low-cost disposal alternative. A greenhouse experiment was conducted to quantify the effects of DWTR on bioaccumulation of some heavy metals in plant tissue and to determine the effects of the DWTR on soil aluminum and aluminum phytotoxicity for the corn plants in alkaline soils. The results indicated that land application of DWTR significantly decreased extractable heavy metals in all studied soils. Combined analyses of all soils and rates of DWTR application showed significant relationship between DTPA-extractable heavy metals and heavy metals uptake of corn plants. Addition of DWTR with different rates (10, 20, 30 and 40 g/kg) to different soil types did not cause aluminum phytotoxicity symptoms for corn plants grown in all studied alkaline agricultural soils because the application rates of DWTR did not increase extractable Al in amended soils > 8 mg Al/kg and the Al phytotoxicity may occur below pH 5.5. Extractable Al is associated with pH of the studied soils, combined analyses of all soils and rates of DWTR application showed a significant relationship between extractable Al and pH. Based on the results of current study, the DWTR is considered an ameliorating material for heavy metals removal from soils; however, additional studies are necessary to confirm these results under field conditions.

A study was conducted in the Shandong province in North China to investigate the effects of different planting patterns on water potential characteristics of soil-plant-atmosphere continuum (SPAC) and yield of summer maize. Three planting patterns were applied, i.e. bed planting (BE), furrow planting (FU) and flat planting (FL). The results showed that although soil moisture content in 0-20 cm soil layer in BE was decreased, soil temperature was increased; as a result, soil water potential in BE was increased. Compared with FL, leaf water potential in BE and FU was enhanced, but water transfer resistance between soil-leaf and leaf-atmosphere was decreased; feasible water supply conditions were thus created for crops colony. Maize yield of BE and FU was significantly (LSD, P < 0.05) higher than that of FL, by 1326.45 and 1243.76 kg/ha, respectively. These results obtained in field crop conditions support the idea that planting patterns affect soil water potential, leaf water potential, water transfer resistance between soil-leaf and leaf-gas of summer maize in North China.

Aquatic plants are known to accumulate heavy metals. In this study, Duckweed plants (Lemna polyrrhiza L.) were exposed to different concentrations of Cd and Pb. Various physio-biochemical parameters (fresh weight, chlorophyll content, soluble protein, soluble sugars, proline content and metal absorption) were studied. At lower metal concentrations, an increase in proline, protein and sugar was observed but at higher concentrations (above 30 mg/l) their decrease was noticed. Uptake of the metals was concentration and time dependent. Treatment with 1, 10 and 20 mg/l of Cd and Pb showed synergistic relation while 30 and 40 mg/l treatments showed antagonistic relation during the metal uptake. The results suggest that the L. polyrrhiza can be effectively used as a phytoremediator for wastewater polluted with more than one heavy metal at moderate concentrations.

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

In order to elucidate the distribution of soil nematodes in coastal wetlands and the effect of different distance from the sea line on soil nematode communities, we investigated the community structure of soil nematodes in one wetland perpendicularly oriented from Bohai sea coastline. In June 2006, soil samples were collected from the Yellow River Delta wetlands, in Dongying city of Shandong Province, China. Soil nematode communities were analyzed at the depths of 0-10 and 10-20 cm. The results showed that plant parasite nematodes were the most abundant trophic groups in both depths and at four sites. The average relative abundance was 91.33% of the nematode community. Several ecological indices which reflected soil nematode community structure, diversity, maturity and plant parasitism were compared in these four sites. The results indicated that the maturity index (MI) and plant parasitism index (PPI) were more sensitive than the other indices for assessing the response of soil nematode communities to soil of coastal wetland.