NP Treatment Research Articles

Estrogenic compounds decrease growth hormone receptor abundance and alter osmoregulation in Atlantic salmon

Exposure of Atlantic salmon smolts to estrogenic compounds is shown to compromise several aspects of smolt development. We sought to determine the underlying endocrine mechanisms of estrogen impacts on the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. Smolts in freshwater (FW) were either injected 3 times over 10days with 2μgg−1 17β-estradiol (E2) or 150μgg−1 4-nonylphenol (NP). Seawater (SW)-acclimated fish received intraperitoneal implants of 30μgg−1 E2 over two weeks. Treatment with these estrogenic compounds increased hepatosomatic index and total plasma calcium. E2 and NP reduced maximum growth hormone binding by 30–60% in hepatic and branchial membranes in FW and SW, but did not alter the dissociation constant. E2 and NP treatment decreased plasma levels of IGF-I levels in both FW and SW. In FW E2 and NP decreased plasma GH whereas in SW plasma GH increased after E2 treatment. Compared to controls, plasma chloride concentrations of E2-treated fish were decreased 5.5mM in FW and increased 10.5mM in SW. There was no effect of NP or E2 on gill sodium–potassium adenosine triphosphatase (Na+/K+-ATPase) activity in FW smolts, whereas E2 treatment in SW reduced gill Na+/K+-ATPase activity and altered the number and size of ionocytes. Our data indicate that E2 downregulates the GH/IGF-I-axis and SW tolerance which may be part of its normal function for reproduction and movement into FW. We conclude that the mechanism of endocrine disruption of smolt development by NP is in part through alteration of the GH/IGF-I axis via reduced GH receptor abundance.

Effects of silver nanoparticles on zebrafish (Danio rerio) and Escherichia coli (ATCC 25922): A comparison of toxicity based on total surface area versus mass concentration of particles in a model eukaryotic and prokaryotic system

Silver nanoparticles (Ag NPs) have been classified as the most abundant NP found in commercial products. In the present study, zebrafish (Danio rerio) and bacteria (Escherichia coli; ATCC 25922) were used to test the size-dependent toxicological effects of Ag NPs, the effects of ionic silver versus Ag NPs, and Ag NP effects on mortality using mass concentration (mg/L) compared with total surface area (nm(2) /L). Several diameters of Ag NPs (20, 50, 110 nm) as well as AgNO(3) were chosen as experimental treatments. Treated zebrafish embryos exhibited anomalies of the heart, namely, slower heart rates and pericardial edema. A size-dependent response was not observed in zebrafish when viewing mortality across all Ag NP treatments, although 20 nm elicited the highest incidence of abnormal motility and induced slower development. An Ag NP dose- and size-dependent response was observed in treated bacteria using mass concentration, with 20-nm Ag NP producing the highest mortality rate. In both zebrafish and bacteria, AgNO(3) was shown to be more toxic than Ag NPs at equivalent concentrations. When total surface area of Ag NPs was used to gauge bacterial mortality, a total surface area-dependent, but not size-dependent, response was observed for all three Ag NPs used in the present study, with nearly 100% mortality observed once a total surface area of approximately 1E + 18 nm(2) /L was reached. This trend was not apparent, however, when measuring total surface area for zebrafish mortality.

Response of plant species composition, biomass production and biomass chemical properties to high N, P and K application rates in Dactylis glomerata‐ and Festuca arundinacea‐dominated grassland

AbstractLittle is known about the immediate effect of high nitrogen (N), phosphorus (P) and potassium (K) application rates on sown grasslands cut twice per year. We asked how quickly plant species composition, biomass yield, biomass chemical properties and nutrient balance respond to N, P and K application. An experiment using unfertilized control, P, N, NP and NPK treatments was established on seven‐year‐old cut grassland in the Czech Republic in 2007 and monitored over four years. Annual application rates were 300 kg N ha−1, 80 kg P ha−1 and 200 kg K ha−1. The immediate response of plant species composition to N application was recorded and was found to be different to the response over the four years of the study period. Highly productive grasses (Dactylis glomerata, Festuca arundinacea and Phleum pratense) were promoted by N application in 2008 and then retreated together with legumes (Medicago sativa, Trifolium pratense and Trifolium repens) in all N treatments where the expansion of perennial forbs (Urtica dioica and Rumex obtusifolius) and annual weeds (Galinsoga quadriradiata, Impatiens parviflora, Lamium purpureum and Stellaria media) was recorded. At the end of the experiment, Festuca rubra was the dominant grass in the control and P treatment, and species richness was lowest in all treatments with N application. Mean annual dry‐matter yield over all years was 3.5, 3.9, 5.8, 5.6 and 6.8 t ha−1 in the control, P, N, NP and NPK treatments, respectively. Concentrations of N in the biomass ranged from 20.0 to 28.7 g kg−1 in the P and N treatments; concentrations of P ranged from 3.2 to 3.7 g kg−1 in the N and P treatments; and concentrations of K ranged from 24.1 to 34.0 g kg−1 in the NP and NPK treatments. The N:P, N:K and K:P ratios did not correctly indicate the nutrient limitation of biomass production, which was primarily N‐limited, and K‐limitation was only recorded for high production levels in treatments with N applications. On the basis of the nutrient‐balance approach, the balanced annual application rates were estimated as 140 kg N ha−1, 30 kg P ha−1 and 100 kg K ha−1. We concluded that high N, P and K application rates can very quickly and dramatically change species composition, biomass production and its chemical properties in sown cut grasslands. High N application rates can be detrimental for tall forage grasses and can support the spread of weedy species.

Effects of contrasting soil management regimes on total and labile soil organic carbon fractions in a loess soil in China

Labile soil organic carbon pools are valuable indicators of soil quality, early changes in soil total organic carbon (TOC) stocks, and (hence) changes in soil carbon sequestration pools and dynamics induced by changes in soil management practices. To improve the management of loess soils in China, we have examined effects of soil and nutrient management treatments applied in a 20-year experiment on TOC and the following fractions: particulate organic carbon (POC), light fraction organic carbon (LFOC), microbial biomass carbon (MBC) and permanganate oxidizable carbon (KMnO4 C). The soil management regimes were cropland abandonment (Abandonment), bare fallow without vegetation (Fallow) and a wheat-maize cropping system (Cropping). Cropping was combined with the following nutrient management treatments: control (CK, no nutrient input), nitrogen only (N), nitrogen and potassium (NK), phosphorus and potassium (PK), NP, NPK, straw plus NPK (SNPK) and two levels of manure (M, 13.7 and 20.6tha−1) plus NPK (M1NPK and M2NPK). After 20years, the Fallow treatment resulted in significantly lower TOC by 22% and labile C fractions by 29%–43% except MBC than Cropping, while Abandonment markedly increased all labile C fractions by 43%–64% except POC relative to Cropping, but the Abandonment and Cropping regimes resulted in similar TOC contents (10.75gkg−1 and 10.16gkg−1, respectively). Of the four C fractions, LFOC and KMnO4 C were the most sensitive indicators of changes in TOC induced by the soil management regimes. Under Cropping, TOC contents were similar in NP, NPK and SNPK plots, and significantly higher than those in CK plots (by 34%, 32% and 45%, respectively). Manure addition further enhanced TOC contents, which were highest following the M2NPK treatment (13.88gkg−1). Labile C fractions were also significantly higher following the treatments including organic amendment than following applications solely of chemical fertilizers, except that the SNPK, NP and NPK treatments resulted in similar LFOC contents. Application solely of chemical fertilizers had no significant effects on LFOC and KMnO4 C fractions compared with CK. Nevertheless, application of NP or NPK significantly increased contents of POC and MBC relative to CK (by 115% and 90% or 31% and 53%, respectively). Thus, LFOC and KMnO4 C fractions were not sensitive indicators of changes in TOC induced by mineral nutrient management practices under current conditions. Overall, given the minor differences between the effects of the NP and NPK treatments, application of manure and NP appears to be the most suitable management practice for improving TOC sequestration in the loess soil.

Alpine plant functional group responses to fertiliser addition depend on abiotic regime and community composition

Background and aimsWe ask how productivity responses of alpine plant communities to increased nutrient availability can be predicted from abiotic regime and initial functional type composition.MethodsWe compared four Caucasian alpine plant communities (lichen heath, Festuca varia grassland, Geranium-Hedysarum meadow, snow bed community) forming a toposequence and contrasting in productivity and dominance structure for biomass responses to experimental fertilization (N, P, NP, Ca) and irrigation for 4–5 years.ResultsThe dominant plants in more productive communities monopolized added N and P, at the expense of their neighbors. In three out of four communities, N and P fertilizations gave greater aboveground biomass increase than N or P fertilization alone, indicating overall co-limitation of N and P, with N being most limiting. Relative biomass increase in NP treatment was negatively related to biomass in control plots across the four communities. Grasses often responded more vigorously to P, but sedges to N alone. Finally, we present one of the rare examples of a forb showing a strong N or NP response.ConclusionOur findings will help improve our ability to predict community composition and biomass dynamics in cool ecosystems subject to changing nutrient availability as induced by climate or land-use changes.

Toxicity of pamam-coated gold nanoparticles in different unicellular models

Polyamidoamine (PAMAM) dendrimers are used for many pharmaceutical and biomedical applications. However, the toxicological risks of several PAMAM-based compounds are still not fully evaluated, despite evidences of PAMAM deleterious effects on biological membranes, leading to toxicity. In this report, we investigated the toxicity of generation 0 PAMAM-coated gold nanoparticles (AuG0 NPs) in four different models to determine how different cellular systems are affected by PAMAM-coated NPs. Toxicity was evaluated in two mammalian cell lines, Neuro 2A and Vero, in the green alga Chlamydomonas reinhardtii and the bacteria Vibrio fischeri. AuG0 NP treatments reduced cell metabolic activity in algal and bacterial cells, measured by esterase enzymatic activity (C. reinhardtii) and luminescence emission (V. fischeri). EC50 value after 30 min of treatment was similar in both organisms, with 0.114 and 0.167 mg mL(-1) for C. reinhardtii and V. fischeri, respectively. On the other hand, AuG0 NPs induced no change of mitochondrial activity in mammalian cells after 24 h of treatment to up to 0.4 mg mL(-1) AuG0 NPs. Change in the absorption spectra of AuG0 NP in the mammalian cell culture media may indicate an alteration of NP properties that contributed to the low toxicity of AuG0 NPs in mammalian cells. For a safe development of PAMAM-based nanomaterials, the difference of sensitivity between mammalian and microbial cells, as well as the modulation of NPs toxicity by medium properties, should be taken into account when designing PAMAM NPs for applications that may lead to their introduction in the environment.

Nitrous oxide emissions from a maize field during two consecutive growing seasons in the North China Plain

Abstract Nitrous oxide (N 2O) emissions from a maize field in the North China Plain (Wangdu County, Hebei Province, China) were investigated using static chambers during two consecutive maize growing seasons in the 2008 and 2009. The N 2O pulse emissions occurred with duration of about 10 days after basal and additional fertilizer applications in the both years. The average N 2O fluxes from the CK (control plot, without crop, fertilization and irrigation), NP (chemical N fertilizer), SN (wheat straw returning plus chemical N fertilizer), OM-1/2N (chicken manure plus half chemical N fertilizer) and OMN (chicken manure plus chemical N fertilizer) plots in 2008 were 8.51, 72.1, 76.6, 101, 107 ng N/(m 2·sec), respectively, and in 2009 were 33.7, 30.0 and 35.0 ng N/(m 2·sec) from CK, NP and SN plots, respectively. The emission factors of the applied fertilizer as N2O-N (EFs) were 3.8% (2008) and 1.1% (2009) for the NP plot, 3.2% (2008) and 1.2% (2009) for the SN plot, and 2.8% and 2.2% in 2008 for the OM-1/2N and OMN plots, respectively. Hydromorphic properties of the investigated soil (with gley) are in favor of denitrification. The large differences of the soil temperature and water-filled pore space (WFPS) between the two maize seasons were suspected to be responsible for the significant yearly variations. Compared with the treatments of NP and SN, chicken manure coupled with compound fertilizer application significantly reduced fertilizer loss rate as N 2O-N.

Cell Growth of BG-1 Ovarian Cancer Cells was Promoted by 4-Tert-octylphenol and 4-Nonylphenol via Downregulation of TGF-β Receptor 2 and Upregulation of c-myc

Transforming growth factor β (TGF-β) is involved in cellular processes including growth, differentiation, apoptosis, migration, and homeostasis. Generally, TGF-β is the inhibitor of cell cycle progression and plays a role in enhancing the antagonistic effects of many growth factors. Unlike the antiproliferative effect of TGF-β, E2, an endogeneous estrogen, is stimulating cell proliferation in the estrogen-dependent organs, which are mediated via the estrogen receptors, ERα and ERβ, and may be considered as a critical risk factor in tumorigenesis of hormone-responsive cancers. Previous researches reported the cross-talk between estrogen/ERα and TGF-β pathway. Especially, based on the E2-mediated inhibition of TGF-β signaling, we examined the inhibition effect of 4-tert-octylphenol (OP) and 4-nonylphenol (NP), which are well known xenoestrogens in endocrine disrupting chemicals (EDCs), on TGF-β signaling via semi-quantitative reverse-transcription PCR. The treatment of E2, OP, or NP resulted in the downregulation of TGF- β receptor2 (TGF-β R2) in TGF-β signaling pathway. However, the expression level of TGF-β1 and TGF- β receptor1 (TGF-β R1) genes was not altered. On the other hand, E2, OP, or NP upregulated the expression of a cell-cycle regulating gene, c-myc, which is a oncogene and a downstream target gene of TGF-β signaling pathway. As a result of downregulation of TGF-β R2 and the upregulation of c-myc, E2, OP, or NP increased cell proliferation of BG-1 ovarian cancer cells. Taken together, these results suggest that E2 and these two EDCs may mediate cancer cell proliferation by inhibiting TGF-β signaling via the downregulation of TGF-β R2 and the upregulation of c-myc oncogene. In addition, it can be inferred that these EDCs have the possibility of tumorigenesis in estrogen-responsive organs by certainly representing estrogenic effect in inhibiting TGF-β signaling.

Long-Term Application of Organic Manure and Mineral Fertilizer on N 2O and CO 2 Emissions in a Red Soil from Cultivated Maize-Wheat Rotation in China

Abstract A long-term field experiment was established to determine the influence of mineral fertilizer and organic manure on soil fertility. A tract of red soil (Ferralic Cambisol) in Qiyang Red Soil Experimental Station (Qiyang County, Hunan Province, China) was fertilized beginning in 1990 and N 2O and CO 2 were examined during the maize and wheat growth season of 2007–2008. The study involved five treatments: organic manure (NPKM), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), and control (CK). Manured soils had higher crop biomass, organic C, and pH than soils receiving the various mineralized fertilizers indicating that long-term application of manures could efficiently prevent red soil acidification and increase crop productivity. The application of manures and fertilizers at a rate of 300 kg N ha −1 yr −1 obviously increased N 2O and CO 2 emissions from 0.58 kg N 2O-N ha −1 yr −1 and 10 565 kg C ha −1 yr −1 in the CK treatment soil to 3.01 kg N 2O-N ha −1 yr −1 and 28 663 kg C ha −1 yr −1 in the NPKM treatment. There were also obvious different effects on N 2O and CO 2 emissions between applying fertilizer and manure. More N 2O and CO 2 released during the 184-d maize growing season than the 125-d wheat growth season in the manure fertilized soils but not in mineral fertilizer treatments. N 2O emission was significantly affected by soil moisture only during the wheat growing season, and CO 2 emission was affected by soil temperature only in CK and NP treatment during the wheat and maize growing season. In sum, this study indicates the application of organic manure may be a preferred strategy for maintaining red soil productivity, but may result in greater N 2O and CO 2 emissions than treatments only with mineral fertilizer.

Effects of 17α‐ethynylestradiol and nonylphenol on liver and gonadal apoptosis and histopathology in Chalcalburnus tarichi

Chalcalburnus tarichi is an endemic cyprinid fish living in the Lake Van basin located in the Eastern Turkey. Fish (3+ ages) were exposed to 17α-ethynylestradiol (EE(2); 1, 10, 100 ng L(-1); nominal concentrations) and nonylphenol (NP; 10, 60, 200 μg L(-1) ; nominal concentrations) for 32 days under semistatic daily renewal conditions. The exposure period was followed by an evaluation of liver and gonadal apoptosis and gonad histopathology in males and females. Exposure to the highest concentrations of EE(2) (100 ng L(-1)) and NP (200 μg L(-1) ) caused significant increases in the extent of apoptosis in liver and gonads. Treatment with 100 ng L(-1) of EE(2) and 200 μg L(-1) NP increased the number of TUNEL positive hepatocytes significantly in both sexes compared to controls. The rates of apoptosis in testicular germ cells and ovarian follicular cells were significantly greater at the same concentrations. Exposure to EE(2) (100 ng L(-1)) and NP (60 and 200 μg L(-1)) caused thickening of interstitial connective tissue (fibrosis) in the seminiferous tubule wall and testis-ova formation in males. In females treated with 100 ng L(-1) EE(2) , increased percentage of atretic ooctytes and fibrotic areas in the ovarian somatic stromal tissue were found in the ovaries. Increase in atresia, without a statistical significance, and fibrotic stromal tissue were also noted in 60 and 200 μg L(-1) NP treatments. Results suggest that EE(2) - and NP-dependent hepatotoxicity and gonadotoxicity are causally related to the increase in apoptosis in C. tarichi.

Antibacterial activities of magnesium oxide (MgO) nanoparticles against foodborne pathogens

The antibacterial activities of magnesium oxide nanoparticles (MgO NP) alone or in combination with other antimicrobials (nisin and ZnO NP) against Escherichia coli O157:H7 and Salmonella Stanley were investigated. The results show that MgO NP have strong bactericidal activity against the pathogens, achieving more than 7 log reductions in bacterial counts. The antibacterial activity of MgO NP increased as the concentrations of MgO increased. A synergistic effect of MgO in combination with nisin was observed as well. However, the addition of ZnO NP to MgO NP did not enhance the antibacterial activity of MgO against both pathogens. Scanning electron microscopy was used to characterize the morphological changes of E. coli O157:H7 before and after antimicrobial treatments. It was revealed that MgO NP treatments distort and damage the cell membrane, resulting in a leakage of intracellular contents and eventually the death of bacterial cells. These results suggest that MgO NP alone or in combination with nisin could potentially be used as an effective antibacterial agent to enhance food safety.

The effects of nutrient additions on particulate and dissolved primary production and metabolic state in surface waters of three Mediterranean eddies

Abstract. We examined the effects of nutrient additions on rates of 14C-based particulate and dissolved primary production as well as O2-based metabolic rates in surface waters (8 m) of three anticyclonic eddies, located in the Western, Central and Eastern Mediterranean. Ship-board microcosm experiments employing additions of inorganic nitrogen (+N) and phosphorus (+P), alone and in combination (+NP), were conducted in June/July 2008 during the BOUM (Biogeochemistry from the Oligotrophic to the Ultra-oligotrophic Mediterranean) cruise. In all three experiments, particulate primary production was significantly stimulated by the additions of nitrogen (+N, +NP) while no effect was observed with the addition of phosphorus alone (+P). Percent extracellular release of photosynthate (PER) displayed the lowest values (4–8 %) in the +NP treatment. Among the three treatments (+N, +P, +NP), the +NP had the strongest effect on oxygen metabolic rates, leading to positive values of net community production (NCP > 0). These changes of NCP were mainly due to enhanced gross primary production (GPP) rather than reduced dark community respiration rates (DCR). In all three sites, in +NP treatment autotrophic production (whether expressed as GPP or PPtotal) was sufficient to fulfil the estimated carbon requirements of heterotrophic prokaryotes, while addition of nitrogen alone (+N) had a weaker effect on GPP, resulting in metabolically balanced systems. At the three sites, in treatments with N (+N, +NP), phytoplankton and heterotrophic prokaryote production were positively correlated. Heterotrophic conditions were observed in the Control and +P treatment at the central and eastern sites, and autotrophic production was not sufficient to supply estimated bacterial carbon demand, evidence of a decoupling of phytoplankton production and consumption by heterotrophic prokaryotes.

Effect of 15-Year-Long Fertilization on Potassium Quantity/Intensity Relationships in Black Soil in Northeastern China

The effect of long-term fertilization and cropping on soil potassium (K)–supplying capacity has not been extensively studied. Five treatments [control, nitrogen (N), N–potassium (P), NPK, and NPK + manure (NPKM)] were used to evaluate the quantity and intensity relationship (Q/I) of K in black soil (Luvic Phaeozems soil) after a 15-year (1990–2005) long-term fertilization with a continuous corn cropping located in Changchun, Jilin Province, northeast China. Results showed that the long-term K fertilization of NPK or NPKM markedly increased the values of equilibrium active ratio (AR0 K) and nonspecifically available K (−ΔK0) but decreased the potential buffering capacity (PBCK) value. Values of the AR0 K and −ΔK0 in the NPK and NPKM treatment were about four and two times greater than those in the control, N, and NP treatments, respectively. Compared with the non-K fertilization, PBCK values were decreased by 40–49% under the K fertilization. The black soil suffered from K deficiency even with NPK fertilization as evidenced from the greater free energies of K+ exchanging for calcium (Ca2+) and magnesium (Mg2+) (−ΔG) (14.7–18.8 kJ mol−1) than the threshold value of 14.6 kJ mol−1, from the lower soil K+ saturation (1.34%–1.44%) than the critical value of 2.00%, and from the response of corn yield to K fertilization. Our results demonstrated that the increment of the current K application rate through fertilizer and/or manure is needed to improve corn yield in the long run in northeastern China.

Silver nanoparticles induce apoptosis and G2/M arrest via PKCζ-dependent signaling in A549 lung cells

The use of silver nanoparticles is one of the fastest growing product categories in the nanotechnology industry, with a focus on antimicrobial activity. However, thus far, toxicity data for silver nanoparticles are limited. In this study, we investigated the cytotoxic effects of silver nanoparticles (Ag NPs) and the pathway by which they affect A549 lung epithelial cells. The effects of Ag NPs on cell survival, cell cycle progression, and mRNA and protein alterations of selected cell cycle- and apoptosis-related genes were studied using formazan dye and LDH release assays, flow cytometric analysis, semi-quantitative RT-PCR, and Western blot analysis. Ag NPs reduced cell viability, increased LDH release, and modulated cell cycle distribution through the accumulation of cells at G2/M and sub-G1 phases (cell death), with a concurrent decrease in cells at G1. Ag NP treatment increased Bax and Bid mRNA levels and downregulated Bcl-2 and Bcl-w mRNAs in a dose-dependent manner. Furthermore, Ag NPs altered the mRNA levels of protein kinase C (PKC) family members. In particular, ectopic overexpression of PKCζ led to the enhancement of cellular proliferation and reduced sensitivity to Ag NPs in A549 cells. Together, these results suggest that Ag NPs induce strong toxicity and G2/M cell cycle arrest by a mechanism involving PKCζ downregulation in A549 cells.

Cu and Pb accumulation in maize (Zea mays L.) and soybean (Glycine max L.) as affected by N, P and K application

Nitrogen (N), phosphorus (P) and potassium (K) fertilizer application affects soil properties and processes in many ways that remain unclear. The effects of N, P, and K application on plant growth and copper (Cu) and lead (Pb) accumulation, as well as their differences in plant species were thus evaluated in soil-maize and soil-soybean systems. Five treatments were arranged: N, P, and K application (NPK), N and P application (NP), N and K application (NK), P and K application (PK), and CK (no fertilization). Results showed that N application could significantly increase maize shoot Cu concentration and translocation from soil to above ground tissue (p<0.05). However, soybean shoot Cu concentration could not increase with N application. Phosphorus application could effectively decrease the bioavailability of Cu and Pb in both systems. Under nutrients deficiency, soil dissolved organic carbon (C) significantly increased, showing difference in plant species (p<0.05), which further enhanced Cu and Pb mobility in soils. Copper removal from soil positively correlated with plant biomass production with the NPK and NP treatments showing the greatest in both crops. Our results show that, an appropriate increase in P application and decrease in N application are recommended to reduce agro-ecological risks associated with Cu and Pb in soil-plant systems. Key words: Soil-plant system, heavy metals, Cu and Pb mobility, ecological risk, translocation.

Shifts in species composition constrain restoration of overgrazed grassland using nitrogen fertilization in Inner Mongolian steppe, China.

Long-term livestock over-grazing causes nitrogen outputs to exceed inputs in Inner Mongolia, suggesting that low levels of nitrogen fertilization could help restore grasslands degraded by overgrazing. However, the effectiveness of such an approach depends on the response of production and species composition to the interactive drivers of nitrogen and water availability. We conducted a five-year experiment manipulating precipitation (NP: natural precipitation and SWP: simulated wet year precipitation) and nitrogen (0, 25 and 50 kg N ha-1 yr-1) addition in Inner Mongolia. We hypothesized that nitrogen fertilization would increase forage production when water availability was relatively high. However, the extent to which nitrogen would co-limit production under average or below average rainfall in these grasslands was unknown.Aboveground net primary production (ANPP) increased in response to nitrogen when precipitation was similar to or higher than the long-term average, but not when precipitation was below average. This shift in limitation was also reflected by water and nitrogen use efficiency. Belowground live biomass significantly increased with increasing water availability, but was not affected by nitrogen addition. Under natural precipitation (NP treatment), the inter-annual variation of ANPP was 3-fold greater than with stable water availability (CVANPP = 61±6% and 17±3% for NP and SWP treatment, respectively) and nitrogen addition increased CVANPP even more (89±14%). This occurred in part because fertilizer nitrogen left in the soil in dry years remained available for uptake during wet years and because of high production by unpalatable annual species in wet years in the NP treatment. In summary, plant growth by residual fertilizer nitrogen could lead to sufficient yields to offset lack of additional production in dry years. However, the utility of fertilization for restoration may be constrained by shifts in species composition and the lack of response by belowground biomass, which reduces replacement of soil carbon and nitrogen.

Effect of potassium fertilization on soil potassium pools and rice response in an intensive cropping system in China

AbstractIn order to assess the changes in soil K pools as affected by K‐fertilizer application and the impact of the changes on K balance, grain yield, and K uptake, an experiment was conducted in Central Zhejiang Province, E China, in a continuous double‐cropping rice system. Two sites were selected: (1) the Agricultural Research Institute of Jinhua (ARI) where soil is calcareous and (2) the Shimen Research Farm (SM) where soil is acidic. Eight consecutive crops were grown (1997–2000) in ARI and five consecutive crops (1998–2000) at SM. Treatments included unfertilized control (CK) and three different fertilizer treatments (NP, NK, and NPK). Potassium extracted by ion‐exchange resin decreased from 26 mg kg–1 to 5–10 mg kg–1 after eight consecutive seasons of growth at the ARI site. Addition of 100 kg K ha–1 for each rice crop was not enough to maintain initial K availability, especially in the calcareous soil at ARI site. In treatments with K, a small increase in readily available K was observed only in SM soil. The K extracted by HNO3 also decreased significantly in the treatments without K addition and was increased slightly in the treatments with K application. In the NP treatment, the decrease in HNO3‐K was several times greater than resin‐K, indicating that nonexchangeable K may be the major source of K supply to rice. Soil K depletion was greater for hybrid rice than for inbred rice, and this difference in K demand should be taken into account in developing fertilizer recommendations for irrigated rice.

EFFECTS OF SINGLE, DUAL AND TRIPLE INOCULATIONS WITH BACILLUS SUBTILIS, BACILLUS MEGATERIUM AND RHIZOBIUM LEGUMINOSARUM BV. PHASEOLI ON NODULATION, NUTRIENT UPTAKE, YIELD AND YIELD PARAMETERS OF COMMON BEAN (PHASEOLUS VULGARIS L. CV. ‘ELKOCA-05’)

This study was conducted in order to investigate the effects of single, dual, and triple inoculations with Rhizobium, N2-fixing Bacillus subtilis (OSU-142), and P-solubilizing Bacillus megaterium (M-3) on nodulation, plant growth, nutrient uptake and seed yield of common bean (Phaseolus vulgaris L. cv. ‘Elkoca-05’) in comparison to control and mineral fertilizer application under field conditions in 2006 and 2007 in the cold highland in Erzurum plateau (29° 55′ N and 41° 16′ E with an altitude of 1850 m), Turkey. Bacterial inoculations significantly increased all the parameters investigated compared with the control treatment, equal to or higher than nitrogen (N), phosphorus (P), and NP treatments. The lowest shoot dry weight and chlorophyll content values were recorded in the control treatment and the bacterial inoculations increased shoot dry weight by 19.7–54.3% and chlorophyll content by 34.1–59.3% over control. Nodule dry weight significantly increased in Rhizobium alone treatment. Additionally, nodulation by native soil Rhizobium population was increased in single inoculations of OSU-142 and M-3. Significant increases of the seed yield under different inoculation treatments ranged between by 6.6% (Rhizobium + OSU-142 + M-3) and 12.2% (OSU-142 alone) over the control whereas N, P and NP applications corresponded to increases of 5.6%, 4.0% and 7.4%, respectively. All bacterial inoculations, especially triple inoculation, significantly increased uptake of macronutrients and micronutrients by common bean. In conclusion, seed inoculation with Rhizobium, OSU-142 and M-3, especially OSU-142 alone, may substitute partially costly NP fertilizers in common bean production even in cold highland areas such as in Erzurum.

Effects of N, P, and K Fertilizer Application on Cotton Growing in Saline Soil in Yellow River Delta

This study aimed at guiding fertilizer management for Bt cotton cultivar SCRC28 growing in coastal saline soil in the Yellow River Delta area in Shandong Province, China. SCRC28 was planted in the soils with high, middle, and low salinity under 3 fertilizer treatments, namely control (no fertilizers), NPK, NP, and NK. The effects of different fertilization treatments on nutrient assimilation, Na + assimilation, net photosynthetic rate ( P n), dry matter accumulation, and lint yield of Bt cotton were investigated. Compared to the corresponding controls, the NP and NPK treatments had significantly higher nutrient uptake levels in plants in the 3 types of saline soils, and significantly lower levels of Na + uptake, especially the NPK treatment. The nutrient use efficiencies in agronomy of cotton in the NPK treatment were the highest among treatments regardless the salinity level. The N use efficiencies in agronomy were 0.20, 1.95, and 2.07 kg lint kg −1 under the low, middle, and high salinity level, respectively; the P use efficiencies in agronomy were 0.87, 8.35, and 8.71 kg lint kg −1, respectively; and the K use efficiencies in agronomy were 0.26, 2.89, and 3.77 kg lint kg −1, respectively. The NPK treatment also maintained the highest levels of leaf area, chlorophyll content, and P n among fertilization treatments in the 3 types of saline soils. The NPK treatment obtained the highest biomass and lint yield among the treatments, and the link yields were enhanced, compared to the corresponding controls, by 2.53%, 28.67%, and 30.47% in the low, middle, and high salinity soils, respectively. The effect of fertilization was obviously in the middle or high salinity fields. In this study, the fertilization quantities were based on the salinity level of soil. The NPK treatments were applied with N 165 kg ha −1 plus P 2O 5 38.57 kg ha −1 plus K 2O 111.5 kg ha −1 in the middle salinity soil and N 135 kg ha −1 plus P 2O 5 32.14 kg ha −1 plus K 2O 74.35 kg ha −1 in the high salinity soil. Therefore, rational fertilization schemes are recommended according to the salinity level of soil in order to alleviate nutrition obstacles and improve cotton nutrition, which ultimately result in the increases of nutrient use efficiencies in agronomy and cotton yield.

Synthesis and Characterization of Tungsten(VI) Alkylidene Complexes Supported by an [OCO]3− Trianionic Pincer Ligand: Progress towards the [tBuOCO]W≡CC(CH3)3 Fragment

The synthesis and characterization of trianionic [tBuOCO]3− pincer-supported tungsten alkylidene and alkylidyne complexes are described. The reaction of an equimolar ratio of (tBuO)3W≡CC(CH3)3 (where tBuO = tert-butoxide) with [tBuOCO]H3 (9) and 2,6-diisopropylphenol affords the alkylidene [tBuOCO]W═CHC(CH3)3(O-2,6-C6H3-iPr2) (10), with a five-coordinate tungsten center that adopts a distorted square-pyramidal geometry. Treatment of (Np)3W≡CC(CH3)3 (11) with 9 provides an equilibrium mixture of the two isomeric alkylidenes with the general formula [(tBuOCO)W═CHC(CH3)3(μ-tBuOCHO)W═CHC(CH3)3(tBuOCO)] (12kin and 12therm). Single crystals of the two isomers cocrystallize and were amenable to X-ray diffraction studies, which revealed subtle differences in their molecular structures, most notably the orientation of the bridging ligand. The complexes are each comprised of two square-pyramidal tungsten ions linked by the diphenolate form of the OCO ligand. Isomer 12kin could not be isolated independently; however...