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Journal of soil science and plant nutrition

Phosphate-induced immobilization is recognized as one of effective in situ remediation methods for heavy metal contaminated soils. Phosphate-based minerals that adsorb, chelate, or complex heavy metals in soil were greatly concerned as effective heavy metals immobilizing materials. Effects of particle sizes of rock phosphate on immobilizing heavy metals in Pb-Zn mine soils by a greenhouse experiment was conducted. Rock phosphate was added to a Pb-Zn mine soil with four different particle sizes, D97<101.43 µm (UP), D97<71.12 µm (P1), D97<36.83 ìm (P2) and D97< 4.26 µm (P3) (the diameters of 97% of the particles were less than 4.26 µm.), and 2 rates (2.5% and 5%). Lolium prenne, L. were grown in the treated soils. Compared to the control, addition of rock phosphate (RP) decreased metal contents in both roots and shoots significantly. Pb contents in shoots decreased by 19.59%-37.80% by different particle sizes at the rate of 5%, reaching lowest level at lowest particle size P3. Zn contents in shoots decreased by 13.47% -13.75 %, Cu in roots was decreased by 18.46%-67.98% and in shoots by 16.82%-32.61%, and Cd in roots decreased by 31.03%-74.23%. The results indicated that, RP can reduce the phytoavailability of Pb, Zn, Cu and Cd in soil significantly by immobilization and the effects strengthened with the decrease of particle size and increasing the rate of addition. 2014/08/01 - 23:01

A field experiment was conducted to assess the efficiency of urea applied with urease inhibitor [N-(n-butyl) thiophosphoric triamide (nBTPT- trade-name Agrotain®), and organic compound (Cytozyme) in minimizing abiotic plant stress in a potato (Solanum tuberosum L.) in Dera Ismail Khan, Pakistan in 2010-2011. The nine treatments of control (no N or Cytozyme), urea applied at 200 and 300 kg N ha-1, Agrotain treated urea applied at 200 and 300 kg N ha-1, urea-200+Cytozyme, urea-300+Cytozyme, Agrotain treated urea-200+Cytozyme, and Agrotain treated urea-300+Cytozyme, were replicated 5 times. Potato growth, yield and quality were significantly influenced by urea applied with Agrotain and Cytozyme. Agrotain treated-urea-200 with Cytozyme resulted in maximum plant survival (91%), plant height (48 cm), plant canopy (61 cm) and the number of stems per plant (3.9 stems) compared to urea alone. Agrotain-treated urea applied at 200 and 300 kg N ha-1 increased potato yield by 46% and 42%, respectively, compared to urea alone. Cytozyme with urea @ 200 and 300 kg N ha-1 increased potato yield by 53% and 35%, respectively, comparing to potato crops receiving urea at the two N rates. Tuber yield improved by 14% when Cytozyme was applied with Agrotain-treated urea at 200 kg N ha-1. Cytozyme and urea applied with Agrotain treated urea-300+Cytozyme produced 33% of large tubers, followed by 31% of medium tubers with urea-200 and Agrotain treated urea-200+Cytozyme. Our results demonstrate that urea applied at 200 kg N ha-1 with either Agrotain or with Cytozyme have the most potential to enhance potato yield. 2014/08/01 - 23:01

A pot experiment was performed to study the Cd-induced alterations in seed quality at maturity in two transgenic upland cotton cultivars, ZD-90 and SGK3, and the upland cotton standard line, TM-1. The results shown that Cd content in cotton kernels increased linearly with the elevation of Cd stress levels. SGK3 accumulated more Cd than others. Protein content in the kernels was increased under Cd stress generally, but those at 600 µM Cd level were lower than that under 400 µM Cd level. The changes in oil content were inversed to that of protein content. Significant ultra-structural changes in cottonseeds were induced by Cd stress, especially at higher Cd levels, which were more obvious in TM-1, followed by ZD-90 and SGK3. Plasmolytic shrinkage, disintegration of nucleus, cell wall thickening, and eventual cell collapse and disintegration were observed in the cells of cottonseeds under Cd stress. Transmission electron microscope (TEM) observation and energy dispersive X-ray analysis (EDAX) confirmed that Cd existed in the form of rings and crystals as well as electron dense granules, occurred in the intercellular space, the cytoplasm, and the cell wall. SGK3 was a tolerance cultivar to Cd stress with greater Cd accumulation and sequestration in cottonseeds. 2014/08/01 - 23:01

The objectives of this paper are to investigate the response of chickpea growing on two iron (Fe) chlorosis-inducing calcareous soils, with different Fe availability, generously supplied with phosphate (P), and to evaluate the effectiveness of a mixture of organic acids (citric, oxalic and malic) to alleviate Fe chlorosis symptoms. Application of P (+P treatment) aggravated Fe deficiency irrespective of the soil. Phosphorus-induced Fe chlorosis was alleviated when organic acids were also applied to the soil (+P+OA treatment), which was reflected in increased leaf chlorophyll concentration and decreased root ferric reductase activity in the plants growing on both soils; the effect was stronger for plants grown on the soil with the lowest Fe-available content. However, Fe chlorosis was still more severe than in the control (-P treatment) plants. The need of -P treatment plants to explore soil in order to take up nutrients is reflected in their root architecture, reduced root diameter and increased length, surface and volume relative to +P and +P+OA roots. Organic acids alleviate Fe chlorosis in function of non crystalline Fe oxides content but inhibit the root response mechanisms as a consequence of increasing Fe concentration in the soil solution. 2014/08/01 - 23:01

To ascertain the levels of urease activities (UA) and their relationships with soil physicochemical properties in salt-affected soils during reclamation, soil transects of a saline-sodic soil with different planting years under drip irrigation were intensively sampled. An enhanced soil UA in root zone (0-40 cm beneath drip emitter) was found as the planting years increased. In all transects, soil UA ranged from 0.38 to 8.53 µg NH4+-N released g-1 dry soil h-1 at 37 °C, and showed a large spatial variability within transect. R² of multiple regressions increased gradually with planting years, indicating that variations in UA could be better predicted after amelioration. Path analysis showed that the negative direct effects of soil pH on UA were clearly dominant, with the direct path coefficients of -0.357 ~ -0.666 (p < 0.05). Soil organic matter yielded greater positive indirect path coefficients through pH and total nitrogen. An exponential relationship was found between soil UA and pH values (p < 0.01). Our findings demonstrate that after the cultivation under drip irrigation for 3 years, soil biological activities and fertility level increased, with the decrease of soil salinity and sodicity. 2014/08/01 - 23:01

With the increasingly acute contradictions between shortage of bonanza phosphorus resources and phosphate fertilizer demands, to develop an efficient use technology for low-grade phosphate rocks (LGPR) was an inevitable choice. In this study, the physicochemical pro-release phosphate rock (PCPR) was prepared by adding modified lignin during the process of ultra-fine grinding LGPR. The relationship between phosphorus chemical composition of PCPR, molecular structure and fertilizer efficiency was explored by chemical analysis, spectral analysis and pot experiment. The results showed that after pro-release treatment of phosphate rock (PR), available phosphorus, reactive phosphorus and soluble phosphorus levels were significantly increased compared with PR. The available phosphorus content increased by 40%, the reactive phosphorus content increased more than 3.5 times, and 6 consecutive extraction soluble phosphorus accumulation increased by 24 times. The structure of the PR showed the pro-release processing would significantly increase particle fineness and specific surface area of PR , strengthen the characteristic absorption peak intensity of PO4(3-), HPO4(2-), replace the Cl-, F-, Fe²+ in the apatite and change the phase composition of PR. Pot experiment results showed corn biomass and phosphorus utilization processed by the PCPR were much higher than superphosphate (SP), diammonium phosphate(DAP), and significantly improve soil phosphorus content. The high soluble phosphorus and active phosphorus in PCPR providing the moderate continuous phosphorus supply intensity was the main reason for its high bioavailability. The combination of a static extraction and continuous extraction of reactive phosphorus and soluble phosphorus was an appropriate evaluation of physicochemical pro-release effect. 2014/08/01 - 23:01

Cyanide occurs naturally in soils, arising from biological cyanogenesis and also in some cases from anthropogenic contamination. Plant utilization of cyanide at non-toxic concentrations as a supplemental source of nitrogen has been a topic of recent scientific interest and it was investigated here using sorghum (Sorghum bicolor L.) and wheat (Triticum aestivum L.). The accumulation of cyanogenic nitrogen in plant tissues was assessed under nitrogen regimes with specific combinations of cyanide, ammonium, and nitrate or each nitrogen source alone. Cyanogenic nitrogen accumulated in plant tissues when in combination with nitrate and accumulation of cyanogenic nitrogen decreased when ammonium was present. A greater increase of nitrogen in tissue from cyanide was observed in both species when cyanide was substituted for ammonium, but accumulation of cyanogenic nitrogen decreased when ammonium was present. A reciprocal nitrogen labeling experiment showed that nitrogen from nitrate and ammonium was accumulated preferentially over cyanogenic nitrogen. Differences in biomass and relative growth rate were observed in response to the treatments where plants were grown with nitrate, ammonium, or cyanide as the sole nitrogen source, but not when cyanide was present along with ammonium and nitrate. Physiological nitrogen use efficiency did not differ significantly within a species for any treatment imposed. The results suggest that cyanide as a nitrogen source can potentially support plant growth and development for up to eight weeks, but more effectively in combination with ammonium and nitrate. 2014/08/01 - 23:01

Compatible solutes rescue plants in the hour of intense water deficit conditions. Glycinebetaine (GB) and potassium (K) are main solutes, playing role in improving plant water potential and ultimately the crop yield. However, only a few attempts have been made so far to study their optimum dozes and interactions to ameliorate the drought stress in wheat. To explore this, GB solutions of 0, 50,100 and 150 mM concentration and K solutions of 0, 0.5, 1.0, and 1.5% concentration were sprayed at milking stage of two wheat varieties under stress (Auqab-2000; drought sensitive and Lasani-2008; drought resistant). The stress was created by withholding water up till appearance of wilting symptoms and then the solutes (alone and/or in combination) were sprayed with carboxymethyl cellulose as a sticking agent, whereas Tween-20 was used as a surfactant for foliar spray. At maturity, ten random plants from field-experiments and three in case of pot experiment were selected to estimate plant height, spike length, number of spikelets spike-1, number of grains spike-1, and grain yields. Besides, water potential, osmotic potential and turgor potential of crop were also estimated. The results indicated that the drought stress adversely affected all the above parameters. The exogenous application of GB and K to wheat significantly improved spike length, number of grain per spike and grain yields. Moreover, a significant interaction between these solutes was observed since at a given level of GB all these yield parameters were increased (p < 0.05) with K concentration. The highest values were obtained when GB and K were applied in combination at 100 mM and 1.5%, respectively. The same treatment also improved the leaf water potential, osmotic potential and turgor potential to maintain plant water potential gradient under stress. These findings lead us to conclude that application of GB and K (100 mM and 1.5%, respectively) is the best strategy to ameliorate the drought impact on wheat at milking stage with improved production. 2014/08/01 - 23:01

The microbial residues, due to their closely connection with humic substances (HS), aroused our considerable interest. The method of shake-flask in liquid culture was adopt to accumulate them, in which the cellulose served as the sole C source. The microbial suspensions including Trichoderma viride (Tv), Aspergillus niger (An), Penicillium (P) and mixed strains (Ms) were inoculated into the cellulose culture fluid respectively. The incubation was performed for 70 days at a constant temperature of 28 °C. The results showed that different microbial treatments had different effects on the C turnover in the cellulose fluid, among which Ms performed the most effective role in accumulating microbial residue and consuming organic C of cell metabolic product, Tv followed. As compared to cellulose, large amounts of inorganic N in the fluid could be transferred into the organic N components of residue. In the mean time, the proportion of aromatic rings could be increased at the cost of losing O-containing groups. Specifically, the degrees of condensation were enhanced by Tv and An, however their degrees of oxidation were inhibited. On the contrary, the P and Ms treatments had a significant advantage in the oxydative degradation of cellulose. Although some intermediate products (polysaccharides, phenolic compounds, carboxylic groups and syringyl units etc.) of HS could be detected in the microbial residues treated by Tv and An, their organic molecules did not still achieve the polymerization degree of real HS. 2014/08/01 - 23:01

At present, the identifying of rice nitrogen stress by the chemical analysis is time-consuming and laborious. Machine vision technology can be used to non-destructively and rapidly identify rice nitrogen status, but image acquisition via digital camera is vulnerable to external conditions, and the images are of poor quality. In this research static scanning technology was used to collect images of the rice's top-three leaves that were fully expand in 4 growth periods. From those images, 14 spectral and shape characteristic parameters were extracted by R, G, B mean value function and Regionprops function in MATLAB. After analyzing, the R, G, Leaf Length, LeafArea, and Leaf Perimeter were chosen as 5 universal characteristic parameters for identifying nitrogen stress in 4 growth periods. The results showed that the overall recognition accuracy of nitrogen stress were 92%, 92%, 100% and 96% respectively. Based on the result, the methodology developed in the study is capable of identifying nitrogen stress accurately in the rice. 2014/08/01 - 23:01

Changes in soil organic carbon, dehydrogenase activity, nutrient availability and leaf nutrient concentrations in a mango orchard soil was evaluated from four years (2007-2011) field experiment on a Typic Ustocrepts soil of subtropical region in Lucknow, India. Organic (FYM, vermicompost, mulching, Azotobacter, PSM and Trichoderma harzianum) and inorganic (N, P, K) substrates were applied each year within the tree basin. It was observed that soil and leaf nutrients concentrations significantly increased in organic and inorganic amended soils as compared to control. Vermicompost, organic mulching and microbial inoculation significantly enhanced soil organic carbon content, available nutrients, dehydrogenase activity and leaf nutrient concentrations. Dehydrogenase activity was highest (1.85 ìg TPF g-1 h-1) in organically treated soils. Surface soil (0-10 cm depth) showed higher dehydrogenase activity (1.29 to 1.85 ìg TPF g-1 h-1) as compared to lower soil depths in all the treatments. 2014/08/01 - 23:01

Crop models are sensitivi by the climatic spatial scale for performing thesimulation. Several crop simulation studies use mesoescale climate database (20-50 km), where topography is neglected. We develop a method to select the optimal climate grid cell resolution (OCGR) based on winter wheat (Triticum aestivum L) yield simulations in complex topographical zones (CTZ) and flat topographical zones (FTZ) in the Araucania Region of Chile (37°35' and 39°37' S - 73°31׳ and 71.31׳ W). The OCGR was estimated from the simulated crop yield (CERES-DSSAT) using a semivariogram to compute the distance, which minimize yield differences with respect to its neighbors. Climate variables were obtained from DGF-PRECIS (25 km) downscaled to a fine resolution of 1 km through Precipitation characterization with Auto-Searched Orographic and Atmospheric (PCASOA). Climate variables were calibrated and validated from 56 in-situ meteorological stations between 1961 and 1991 and the yield was validated from field experiments. The crop simulation presented no significant differences (3.0±0.3-3.0±0.1 Mg ha-1) compared to field experiments. Increasing the resolution improves the crop simulation reducing the RSME from 0.8 to 0.32 Mg ha-1 The OCGR estimated averaged < 7 km for CTZ, whereas it was > 25 km for FTZ. Our approach can be applied for similar crops and complex topographical zones. 2014/08/01 - 23:01

The purpose of this work was to study vineyards of NE Italy seeking for features associated to the soil or plant compartment that could serve as proxies to infer productivity of the grape. Soils were characterized for physico-chemical properties, mineralization of organic matter by a novel patented device based on in-situ microbial degradation of buried fibers, bacterial intergenic spacer length diversity (ARISA), enzyme activities and the expression of genes involved in response to abiotic stresses. Significant differences (p<0.05) were observed among vineyards for the parameters evaluated. The groupings obtained by ARISA were coherent with those obtained by PCA of soil properties. Vineyards endowed with higher productivity had soils showing higher enzyme activities along with neutral pH, higher TOC content and appropriate C/N ratio. These soils also showed higher mineralization of organic matter determined the novel in-soil thread degradation method. Grapevines of less productive vineyards had suboptimal leaf nitrogen and sulfur contents and showed up-regulation of WRKY, SuSy, PAL and STS1 genes. Results put in evidence useful correlations with yield that can be obtained up to several months earlier than harvest time upon analyzing selected indicators. An interesting link arises unifying soil biological properties, nutritional status, molecular stress response of grapevine and its production level. 2014/08/01 - 23:01

Nitric oxide (NO) is involved in numerous physiological and stress responses in higher plants. Tomato is one of the most important vegetable crops in the world and previously it has been reported that salinity induced an oxidative stress affecting its redox and NO homeostasis. Using tomato plant exposed to 120 mM NaCl, it was studied whether the exogenous application of NO could ameliorate the negative effects provoked by salinity. Thus, nitric oxide provoked a significantly increase in the main antioxidative enzymes including superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and peroxidase (POD) activities, and also a raise of some enzymes involved in nitrogen metabolism including nitrate reductase (NR) and nitrite reductase (NiR) activities. Moreover, NO-treated plants showed a higher content in both proline and ascorbate but lower content of H2O2. These data indicate that the exogenous NO application is useful to mitigate the salinity-induced oxidative stress in tomato plants. 2014/08/01 - 23:01

Sensitivity of common onion (Allium cepa L.) and faba bean (Viciafaba L.) to cadmium (Cd) stress was investigated using genotoxicity endpoints. Simultaneously, the antioxidative stress enzymes (guaiacol peroxidise and catalase) and lipid peroxidation [malonaldehyde MDA) conten] were investigated in the plants exposed to Cd in solution. The endpoints screened for genotoxicity included chromosomal aberrations, micronuclei frequency and mitotic frequency. Additionally comet assay was performed for DNA fragmentation. Evan's blue uptake by the root meristems as a cell death parameter served as indicator of cytotoxicity. The results indicated that exposure to Cd induced dose-dependent increase in chromosomal aberrations, DNA fragmentation and micronucleus frequency in both A.cepa and V. faba. The enzymes guaiacol peroxidase (GPX) and catalase (CAT) activities increased in both the plants and were higher in V. faba. A positive correlation between the activity of GPX and CAT and MDA content was recorded at all concentrations of Cd. Regarding sensitivity, our results showed that V. faba is more sensitive plant than A. cepa towards Cd -induced toxicity. Higher genotoxicity level correlated to the increased level of oxidative stress in root tissues. This was likely to be an important cause of Vicia plant to be less tolerant than Allium. 2014/08/01 - 23:01

Micronutrient malnutrition among humans is typically caused by micronutrient deficiency in soils and then staple food crops grown on these soils. In this study, field trials were conducted to investigate the biofortification of micronutrients in the edible parts of winter wheat, maize, soybean, potato, canola, and cabbage. Fertilizers of Se, Zn and I were applied to soil independently or together, while Se and Zn were sprayed as solution on winter wheat in another part of the trials. Selenium, when applied to the soil in the form of sodium selenate, whether alone or combined with Zn and/or I, was effective in increasing Se to around target levels in all of the tested crops. Selenium as sodium selenite was effective as a foliar application to winter wheat, increasing it from 25 to 312 µg kg-1 in wheat grain with 60 g Se ha-1. For Zn, soil-applied zinc sulphate was only found to be effective for increasing the Zn concentration in cabbage leaf and canola seed, with 35 and 61 mg kg-1, respectively, while foliar zinc sulphate application was effective in biofortifying winter wheat, increasing grain Zn from 20 to 30 mg kg-1. While for I, soil-applied potassium iodate was only effective in increasing I concentration in cabbage leaf, and biofortification of the other crops was not possible. The enhancements of Se, Zn, and I concentration resulting from either the single or combined application of microelement fertilizers were similar. Therefore, agronomic biofortification of edible parts of various food crops with Zn, Se, and I can be an effective way to increase micronutrient concentrations, and the effectiveness depends on crop species, fertilizer forms and application methods. 2014/08/01 - 23:01

Switchgrass (Panicum virgatum L.) is a bunchgrass native to North America recently successively cultivated as an energy crop. The use of compost as soil amendment is a universal practice well known for its benefits to soil properties and plant growth. This study aimed to assess the possible benefits of compost addition on the growth parameters of four switchgrass populations, the octaploids Shelter, Shawnee and Dacotah, and the tetraploid Alamo, in pot experiments. Three growing media were prepared by mixing peat (P) with each of three different composts, a green compost (GC), a mixed compost (MC) and a coffee compost (CC), at the percentages of 5%, 10% and 20% (v/v). Results obtained showed that, with respect to the use of P only, all compost mixtures exerted positive effects on root, shoot and primary leaf lengths and on the fresh weight of the different switchgrass populations. In particular, GC/P and MC/P mixtures appeared more efficient at 5% and 10% of compost, whereas CC/P mixtures produced the best results at 10% and 20% of compost. The effects of composts were more evident for the Shawnee population and less for the Shelter one, thus indicating an involvement of the genotype in the plant response. 2014/08/01 - 23:01

This study evaluated how the fresh fine sawdust from Pinewood affects some hydro-physical properties of expansive soil which collected from the middle Nile Delta, Egypt. To fulfil this objective, a number of laboratory tests were carried on the clay loam soil samples collected from the depth of 0-30 cm. Clay loam soils were treated by sawdust at the rate of 0%, 1%, 2%, 5%, 10%, 15% and 20% on the dry weight basis. Various experimental methods were used to determine the variations in the falling-head permeability, the clay size fraction, the plasticity index, the linear shrinkage and the cracking width with different sawdust-amended soils. The results showed that the addition of sawdust decreases the clay size fraction, the plasticity index, the linear shrinkage and the cracking width, while it increases significantly the falling-head permeability, which is a sign improvement of soil hydro-physical properties. It can be concluded that sawdust had the potential to improve the hydro-physical properties of expansive soils, especially, when added into soil in between one to two percent on dry weight basis, above this percentage the improvement was much less significant and warranted by the clay content decrease. 2014/08/01 - 23:01

In this study, bacteria were isolated from the rhizosphere and inside the roots of canola (Brassica napus L.) plants grown in the field from northern Iran. Firstly, 150 strains (endophytic and rhizospheric isolates) isolated from canola were characterized for plant growth promoting (PGP) traits. Of them, one hundred isolates produced indole-3-acetic acid (IAA), whereas 17 isolates solubilized phosphate, 44 isolates produced siderophore, 34 produced 1-aminocyclopropane-1-carboxylate (ACC) deaminase and five produced hydrocyanic acid (HCN). All of the screened isolates with different growth promoting traits were separately inoculated as different mixtures on two rice cultivars under gnotobiotic conditions. A total of 22 endophytic isolates were re-isolated from two rice cultivars and characterized for Plant Growth Promoting (PGP) traits again. All 22 endophytic isolates produced IAA. Secondly, the colonization and growth promoting effects of the IAA producing endophytic strains were compared in inoculated rice plantlets as single-strain inoculants. All of the IAA producing strains were consistently more active in colonizing rice seedlings as compared with other isolates. Therefore, it seems that IAA production may be required for endophytic competence as compared to other PGP traits in rice seedlings. In addition, this study indicates that the selected bacterial isolates based on their IAA producing trait have the potential for PGP and more colonization of rice. 2014/08/01 - 23:01

Plant growth promoting rhizobacteria (PGPRs) improve growth of the host plants in a variety of ways. For this reason five bacterial strains isolated form the rice rhizospheric soil (B 15, B 17, B 19, BN 17 and BN 30) and three standard PGPR strains (viz. Pseudomonas putida, Pseudomonasfluorescens and Azospirillum lipoferum) were tested for plant growth promotion when applied to the rice plants as seedling treatments. The experiment was conducted for two rainy seasons of the years 2010 and 2011. Rice plants inoculated with the bacterial isolates recorded an improved plant growth and higher photosynthetic capacity signified by the higher chlorophyll content. Root and shoot dry mass was also found to be increased in the inoculated plants. Besides these iron and zinc content of the treated rice plants was also found to be higher in comparison with the uninoculated control plants. Hence, it can be concluded that application of PGPR has immense potential to be used as agricultural crop inoculants as they promote plant growth as well as improve the health and yield of the plants. 2014/08/01 - 23:01

In the present investigation, the role of sodium nitroprusside (SNP, a donor of NO) in inducing salinity tolerance (100 mM NaCl) in cotton was studied. Salt stress reduced the values of photosynthetic attributes and total chlorophyll content and inhibited the activities of nitrate reductase. Furthermore, salt stress also induced oxidative stress as indicated by the elevated levels of lipid peroxidation compared to CK. The application of SNP at 1.00 mM promoted the growth and restrained superoxide anions (O2.-) generation rate. And activities of antioxidant enzymes, namely, catalase (CAT) and superoxide dismutase (SOD), were enhanced by SNP treatment. On the other hand, an increase in the K+ content, antioxidant enzyme activities, along with a decrease in the Na+/K+ ratio, the contents of thiobarbituric acid reactive substances (TBARS) and malondialdehyde (MDA) were observed in the NaCl-stressed seedlings subjected to the low level (0.1 mM) SNP. These results indicated that the application of moderate SNP can be used to protect plants growth and induce its antioxidant defense system under salt stress. 2014/05/15 - 22:03

Use and management ofjatropha residue is currently an important global issue for attaining sustainability in biofuel production from Jatropha curcas on wastelands. Perhaps, knowledge about the decomposition characteristics and nutrient release pattern from jatropha residues amended soils are lacking. Thus, the objective of present research was to characterize the carbon (C) and nitrogen (N) mineralization of jatropha residues during decomposition in soil. The chemical composition of the residues, in terms of C, N, cellulose, hemicelluloses, lignin and phenolics contents were determined. Laboratory incubation studies were carried out with two soils (inside and outside-canopy soil ofjatropha shrub) and four jatropha residues (1% w/w) amendments (cake, leaf, fruit shell or control soil only). The cumulative CO2 evolution of the added residues was in the magnitude of fruit shell>leaf>cake>control soil. Net C mineralized in soils were in the range of 46-50, 66-67 and 75-77% of C added by cake, leaf and fruit shell, respectively at the end of incubation study. Soils amended with leaf immobilized N during the first 64 days but subsequently released inorganic N. The addition of cake and fruit shell resulted in net N mineralization and net N immobilization, respectively throughout the incubation period. Cumulative N released by the end of incubation was in the order of cake>leaf>control>fruit shell. Net N mineralization in soils during the study was 75-92 and 21-27% of N added by cake and leaf, respectively whereas there was net N immobilization in fruit shell amended soil. Cumulative CO2 evolution as well as N mineralization during incubation were higher in inside-canopy soil compared with that of outside-canopy soil. Jatropha cake and leaf proved to be a potential source of mineral N, however leaf will take about 60-70 days as gestation period to mineralize the nitrogen. Similarly, leaf and fruit shell also exhibited a good potential of C mineralization. 2014/05/15 - 22:03

The purpose of this study was to investigate the influence of microbial biomass on the litter decomposition in relation to litter quality, litterfall, canopy leaf area and soil characteristics. The mean values for litterfall were 4245, 3510 and 2935 kg ha-1 year-1 for beech, fir-beech and fir stands, respectively. In the research area, beech stand has higher litterfall than fir, this may be attributed to high allocation of biomass to leaves, thus, makes them fall as litter more easily. One-year mass loss of litter decreased in this order: fir (23.6%) > fir-beech (17.2%) > beech (13.16%). Annual decay constant was significantly lower for beech (k=0.159) than fir litter (k=0.254), reflecting differences in nitrogen and lignin content between litter types (beech, 0.63% and 36.15%; fir, 1.40% and 28.10%). Fir litters have greater microbial biomass C content during the sampling period compared with beech and fir-beech litters. Microbial communities in fir litter were energetically more efficient (had a lower gCO2) with a higher Cmic/Corg compared to those in beech leaf litter. The results of this study indicate that admixed fir needles tended to speed up decomposition of beech foliage in these types of forest ecosystems. 2014/05/15 - 22:03

Broomrapes (Orobanche sp.) are a root holoparasitic plant devoid of chlorophyll and entirely depending on the host for nutritional requirements. They cause considerable yield losses (5-100 %) in the crops, especially in the drier and warmer areas of Europe, Africa and Asia where it is reported to mainly parasitize species of leguminous, oilseeds, solanaceous, cruciferous and medicinal plants. It is a serious root parasite threatening the livelihood of the farmers with its devastating effect on the some of aforementioned crops. The long-term impact of the broomrapes is even more serious: their seeds may easily spread to other fields, and can persist in soil up to 20 years, leading to an accelerated increase in the infested areas in which susceptible crops are under danger. Orobanche seed dispersal is facilitated by man, agricultural tools, crop seeds, propagules and also by animals through their excreta. This review will discuss and summarize alternative methods viz preventive, physical, chemical, agronomic, biological, crop resistance and integrated methods which are needed to manage this parasite. However, the main concern is that, up to date, no single cheap method of control proved to be effective, economical and complete in protection against this parasite. For that reason, an integrated approach is needed in which a variety of such techniques are combined, in order to maintain parasite populations below threshold levels of damage. 2014/05/15 - 22:03

Biocontrol traits of arbuscular mycorrhizal fungi (AMF), in terms of single and mixed species inoculum, against the root knot nematode Meloidogyne incongita in Impatiens balsamina L., were examined with and without mineral fertilization in a greenhouse pot experiment. At harvest, 60 days after sowing, general plant growth parameters and plant defense response in terms of antioxidant activity and content of phenolic compounds in roots and leaves were measured. Also AMF root colonization and abundance ofnematode root-knots were determined. Mineral fertilization increased all plant growth parameters measured, which coincided with an increased disease development caused by M. incognita. Inoculation with AMF mitigated the observed plant growth reduction caused by M.incognita, though, higher abundance of M. incognita root knots was found in mycorrhizal plants. Plant defense responses in terms of antioxidant activity and content of phenolic compounds did not seem to be linked to the observed biocontrol traits of AMF against M. incognita. However, roots inoculated with a consortium of AMF, which presented less nematode root knots than roots with the single species inoculum, had the highest level of phenolic compounds. The results from the present study suggest that AMF induce tolerance in I. balsamina against the root knot nematode M. incognita. 2014/05/15 - 22:03

To understand changes in soil nutrients in Pinus massoniana forests affected by pine wilt disease (PWD), we examined the seasonal variation in dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and soil nutrients in Hefei, East China. The results showed a considerable decline in the population density and basal area in both highly disturbed (HD) and moderately disturbed (MD) forest stands and an increase in dead pine trees, causing pronounced changes in the stand structure and soil nutrient status. The concentrations of DOC and NO3-- N were significantly (p < 0.05) higher in every season in the disturbed forests compared to the undisturbed (UD) forest stand. However, during spring and summer, the variation in the DON and NH4+-N values was significantly (p < 0.05) lower in the HD forest stand than in the UD stand; total N concentrations were higher in the disturbed forests in every season. During spring and autumn, the variation in total P values was significantly (p < 0.05) lower in the MD forest stand than in the UD stand, whereas the total P values were significantly (p < 0.05) lower in every season in the HD stand than in the UD stand. In this study, disturbance resulted in a considerable increase in DOC, N and NO3-- N when compared to the UD stand and a pronounced increase in soil nitrate in the HD stand, which may lead to soil acidification, thereby increasing the possibility of soil nutrient leaching. 2014/05/15 - 22:03

Plant nutrients might affect the activity and bioavailability of heavy metals in the soil -plant environment thus their accumulation in the plant. Little is known about the effect of nitrogen fertilization on cadmium (Cd) uptake by alfalfa "Medicago sativa". This work aims to characterize the oxidative status, the physiological stress parameters and the Cd uptake in alfalfa + Medicago sativa ; exposed to Cd and supplied with nitrogen fertilizers. The experiment was carried out in a green house with alfalfa grown in Cd-polluted soil (3.6 ppm) and amended with two different fertilizers: without NO3- (PK) or with NO3- (NPK) in a sand:peat (v:v) mixture. The following parameters were monitored: Chlorophyll content, Photosynthesis rate, Catalase (CAT) activity, Thiobarbutiric Acid Reactive Species (TBARS) content and Cd bioaccumulation. It was found that NPK fertilization increased mean Cd uptake as well as plant biomass in Cd-exposed plants. Nitrogen supply was also effective in reduction Cd-induces phytotoxicity (Photosynthetic pigments and rate) and oxidative stress alterations. Our results suggest that nitrogen supply may improve the uptake rate of Cd by alfalfa and provide new insights on the importance of nitrogen fertilization towards future phytoremediation applications using alfalfa. 2014/05/15 - 22:03

Soil scarification has been used as a silvicultura! method to eliminate competition in tree regeneration, but it modifies soil characteristics. In order to evaluate soil changes due to silvicultural management, we characterized a volcanic soil subjected to a mechanized scarification in a Nothofagus spp. forest in the Andean region of southern Chile (390 54' S, 710 56' W; 970 m asl). Scarification removed between 20 and 40 cm of topsoil in forest gaps. Two scarified areas were selected in different periods and in an undisturbed forest area. Physical properties (bulk density, penetration resistance, porosity, texture) and chemical (pH, soil organic matter, total-N, P-Olsen, K, Mg and Ca extractable, Al saturation) were analyzed in both the scarified soil and undisturbed forest. The morphology of the soil was a result of the formation of a stratified soil. Bulk density was higher in the superficial layer of the scarified soil (0.9 to 1.2 g cm-3) when compared to the undisturbed forest (0.3 g cm-3). With regards to the undisturbed forest, soil scarification exposed a superficial soil of coarser texture, lower total porosity (50-60% vs. 80%) and it decreased the soil nutrient supply. There were no large variations in soil properties when comparing the oldest scarified soil with the most recent one. There were important changes in morphology, physical and chemical properties of the scarified soil. 2014/05/15 - 22:03

Soil scarification has been used as a silvicultura method to facilitate the regeneration of some forests, but it may have a negative impact on the properties of the soil. We evaluated the effect of a mechanized scarification on a volcanic soil after a shelterwood cutting in a Nothofagus spp. forest, located in the Andean region of southern Chile (39° 54 'S, 71° 56' 5 W, 970 m asl). A plantation of Nothofagus nervosa was established after scarification, and its physical (moisture content, bulk density, penetration resistance) and chemical (pH, organic matter, macro and microelements; saturation Al) soil properties were analyzed in scarified gaps and undisturbed forest. The size of N. nervosa planted trees was measured eleven months after their establishment (June 2010). The volumetric water content of the soil was similar with and without scarification (30-50%), regardless of the time of year. The bulk density was higher in the scarified soil when compared to the undisturbed forest. The soil nutrient supply in the gaps (0-20 cm) decreased when compared to the undisturbed forest (0-10 cm), but showed little difference between gaps and between locations within them. The N. nervosa plantation developed properly, with similar growth in gaps of different size. Scarification decreased soil quality; the effects on regeneration will need further evaluation throughout a longer period. 2014/05/15 - 22:03

One of the major problems for biodiesel producers is the disposal of the seed cake after expelling oil from seeds. Every ton of biodiesel results in 2.5 to 3 tons of seed cake as byproduct. The physicochemical characteristics of this residue indicate that it could be converted into valuable organic fertilizer. In order to evaluate the feasibility of using chañar seed cake from biodiesel production as a soil amendment, a greenhouse pot experiment was conducted. Seed cake was applied mixed with soil, at rates of 0, 6, 12 and 24%. A single seedling of chañar per pot was transplanted and after six months, plants were harvested for foliar analyses as well as some physiological characteristics. Seed cake application increased dry biomass production and the shoot concentrations of N and chlorophyll. There were no evident symptoms of phytotoxicity. The application of seed cake at 12% proved superior to the 6% treatment and the control; ahigher dose of seed cake (24%) was not significantly different from the treatment with 12% in terms of dry biomass production of chañar, foliar contents of N, P, Kor total chlorophyll. However, plant aerial biomass was significantly correlated with soil microbial respiration and soil C biomass. 2014/05/15 - 22:03

A field experiment was carried out to study the changes of soil bacteria, fungi and actinomycetes in saline-sodic soils for different numbers of cultivated years under drip irrigation. The drip irrigation had substantial effects on levels of bacteria, fungi and actinomycetes. With increased number of cultivated years under drip irrigation, the soil biological properties were greatly improved. After three years of cultivation, the respective increases in the levels of bacteria, fungi and actinomycetes were 103.7, 72.7 and 58.2 times those of uncultivated land. In the vertical direction, the colony forming units of bacteria, fungi and actinomycetes all decreased with increased soil depth. We forecast that the soil microbial characteristics in drip-irrigated saline-sodic soils should match those of natural Leymus chinensis grassland after 6-7 years of cultivation. 2014/05/15 - 22:03

Knowledge of microbiological characteristics in the plant rhizosphere is essential for understanding the fate and transport of agricultural chemicals in soils. The present study was conducted to investigate the effects of an acetanilide herbicide napropamide on microbiological characteristics of tobacco (Nicotiana tabacum K326) rhizosphere soil and its dissipation behaviors under controlled conditions. The results showed that both microbial populations and enzymatic activities in rhizosphere soil were higher than those in non-rhizosphere soil. The populations of bacteria and actinomycetes decreased with napropamide addition in rhizosphere soil, while the populations of fungi displayed the decreasing, recovering and increasing trend throughout the incubation period. The activities of dehydrogenase and catalase were stimulated firstly, owing to napropamide addition, then were inhibited, and recovered to the control level, whereas the activities of urease were inhibited obviously during the testing stage. Napropamide rapidly dissipated in vegetated soil suggests that rhizosphere soil is a useful pathway to rapidly remove or detoxify herbicide residues. 2014/05/15 - 22:03

To gain a better knowledge of mining areas and potential remediation processes, some characteristics (morphological, physical, chemical and microbiological) of soils formed on open-pit Cu mine waste (OPW) and Cu post-flotation tailings (PFT) dumps were investigated. Soil profiles and surface samples were studied. In general, the investigated soils are characterized by large proportion of coarse soil particles, degraded structure, low humus content, low pH, high As and Cu concentrations, and low soil microbial activity. In all investigated profiles there is no recognizable topsoil layer containing in situ formed humus probably due to soil age, lack of plant cover and organic litter, as well as other unfavorable soil conditions. The specificity of investigated soils is an irregular distribution of some soil characteristics (porosity, humus content, microbiological activity) over depth, which is a result of their technogenic origin. By establishing correlations between the studied surface sample parameters, using principal component analysis (PCA), poorer aggregate properties of PFT than of OPW soils were found, resulting most likely from aggressive mining, i.e., flotation processes. Both OPW and PFT soils compared with control natural soils are characterized by lower clay and humus content, and poorer aggregate properties. 2014/05/15 - 22:03

The associations of Fusarium root rot (FRR) and yield variables with a number of soil characteristics were determined at pod maturity in 122 commercial bean fields in Zanjan, Iran. Mean pod and seed numbers per plant at a sand content level of 45-65% were lower than those at a level of 25-45%. Higher FRR index and fewer pods were detected in field soils with 30-48% silt content compared to 15-30% level. FRR index was higher in field soils treated with fungicides compared to non-treated soils. The lowest FRR index and highest yields occurred in the soils with the highest level of organic matter, 1.2-1.8%. The greatest FRR index and lowest yield levels were observed in non-nodulated beans compared to low- and high-nodulated beans. Soil pH and organic matter were negatively correlated with FRR variables. According to loadings for second principal component, the most relevant soil characteristic to FRR was pH, followed by organic matter, clay and sand content. There were spatial FRR correlations among bean fields. Organic matter was the most effective factor among the soil properties surveyed to improve bean productivity. This new information extends our knowledge over interactions between FRR, yield and various soil variables in commercial bean fields. 2014/05/15 - 22:03

We have studied the effects of P fertilization and AMF inoculation on the growth of escarole (Chicorium endivia L.) plants ,grown in both As-non-contaminated (Padula) and As-contaminated (La Botte) soils and As and P uptake by these plants. Our study demonstrated that the combined use of AMF inoculation and P fertilization can significantly increase the production of biomass of escarole plants, even if grown in highly As-contaminated soils. In addition, this dual agricultural practice has also allowed to reduce the translocation of the harmful element from roots to leaves minimizing, hence, the accumulation of highly toxic levels of As in the edible part of the escarole. Therefore, the combined use of AMF inoculation and P fertilization may alleviate the As toxicity to sensitive plants as Cichorium endivia, by promoting their growth, limiting As assimilation and improving P nutrition. 2014/05/15 - 22:03

The present work, examined the effect of salinity (5, 40 and 120 mmol L-1 NaCl) in the growth and the quality of hydroponic culture of stamnagathi (Cichorium spinosum L.). Plants were developed in perlite, pumice, rockwool and sand respectively. High salinity decreased leaf number, leaf size and plant biomass in plants grown in perlite, pumice and sand. Reduced plant biomass also observed in plant grown in rockwool, although an increased number of leaves were produced. Leaf area reduced in plants grown in rockwool and sand under 120 mmol L-1 NaCl. Low salinity maintained almost similar status as the control treatments. Symptoms of tip burn appeared in 120 mmol L-1 NaCl treated stamnagathi for perlite and pumice. No differences observed in leaf chlorophyll content, leaf fluorescence and in symptoms of discoloration. When the perlite was used as substrate, salinity increased total phenols and decreased protein content. Finally, the low concentration of salinity improved some plant quality parameters as recorded by panelists, following organoleptic test. Thus, stamnagathi proved to successfully tolerate low salinity concentration in hydroponically grown plants. 2014/05/15 - 22:03

In conventional agriculture, heavy doses of chemical fertilizers and pesticides are often used to improve the yield of various horticultural crops. These chemical fertilizers and pesticides cause health problems among consumers. Due to the adverse effects of chemical fertilizers, there is interest in the use of organic fertilizers. It has long been recognized that the rate-limiting step for nitrogen assimilation, the reduction of NO3- to NO2- catalyzed by nitrate reductase (NR), is highly regulated. An increase in the amount and activity of NR leads to a corresponding increase in the potential for nitrate reduction and confers a greater capacity for general amino-acid synthesis, protein synthesis or total nitrogen assimilation. The aim of the current experiment was to determine the effect of organic and conventional fertilizers on yield and nitrate reductase activity in saladette tomato.Tomato plants were grown under controlled greenhouse conditions and treated with either organic or conventional fertilizer. We evaluated five treatments: F1, sand + inorganic fertilizer; F2, sand + vermicompost tea; F3, a 1:1 mixture of sand: compost + vermicompost tea; F4, a 1:1 mixture of sand: vermicompost + vermicompost tea; and F5, a 2:1:1 mixture of sand: compost: vermicompost + vermicompost tea. The evaluated variables were yield, fruit size, number of fruits, fruit quality, chlorophyll content, and in vivo nitrate reductase enzyme activity. Fertilizer type strongly influenced the yield, fruit size, and fruit quality. The best organic fertilizer for tomatoes was sand + vermicompost tea. Tomatoes in this treatment group produced the second highest yield, the best NO3- assimilation, the greatest nitrate reductase enzyme activity, and the second highest organic foliar nitrogen content. 2014/05/15 - 22:03

Thirteen genotypes of sugarcane were exposed to different drought stress intensities followed by a period of stress relief. Different biomarkers were used to analyze the stress tolerance in leaves which include DPPH activity, proline, glycine betaine, lipid peroxidation and phenolic contents against different doses of Polyethylene glycol. Relatively the concentrations of all biochemical markers were increased when PEG concentration was increased. On the basis of lipid peroxidation, glycine betaine and proline contents, HSF-242, Lho-83, HSF-240, CP-77-400, CPF-198, NSG-45, NSG-60 and NSG-555 were found to be drought tolerant genotypes. In conclusion the drought stress-induced changes are reversible, at the cellular level in sugarcane. 2014/05/15 - 22:03

A one year field experiment was conducted to assess the efficiency of urea fertilizer applied to pasture near Lincoln University, New Zealand. Urea with or without () molybdenum (Mo) were applied to field plot, with a urease inhibitor [N-(n-butyl) thiophosphoric triamide (nBTPT), nBTPT + elemental sulphur (S), and nitrification inhibitor dicyandiamide (DCD) + nBTPT defined as a double inhibitor (DI) in spring 2005. Mo was sprayed at the rate of 50 g Mo/ha/yr once. Urea various inhibitor and S treatments were broadcast at a rate of 30 kg N/ha 5 times over one year. The Mo alone treatment increased pasture dry matter (PDM) yield by 8.9%. Molybdenum, when applied together with urea+nBTPT+S, urea+nBTPT and urea alone, caused an initial depression in PDM yield by 14.2, 13 and 5.6% respectively. However, these depressions in yield disappeared from the second pasture cut. Over a one year period, Mo applied with urea+nBTPT, urea+DI and urea+nBTPT+S produced 18179, 16716 and 18253 kg DM ha-1 respectively, compared to 16171 kg ha-1 for urea+Mo. Pastures which received no Mo, but were treated with urea+nBTPT+S, or urea+nBTPT produced 18982 and 18276 kg DM ha-1 respectively, compared to 16363 kg ha-1 for urea alone, giving an increase of 16% and 12% over urea alone. Pastures receiving Mo, together with urea+nBTPT or urea+nBTPT+S, also showed improvement in N uptake and N recovery, compared to urea alone. Applying urea with nBTPT and S have the most potential to improve urea efficiency. 2014/05/15 - 22:03