• Authors:
    • Szendrei, Z.
  • Source: Entomologia Experimentalis et Applicata
  • Volume: 143
  • Issue: 2
  • Year: 2012
  • Summary: Habitat diversification can influence the interactions of insects with plants and this can be used in agroecosystems for the management of pest populations. Plant diversification can be achieved through planting crops, such as trap crops, or by adjusting weed management. Aster leafhopper, Macrosteles quadrilineatus Forbes (Hemiptera: Cicadellidae), is a polyphagous species that uses cereals, vegetables, and weeds as host plants. The influence of weeds on M. quadrilineatus abundance was investigated experimentally in carrot [ Daucus carota L. cv. Canada (Apiaceae)] field plots by adjusting the level of management of two groups of weeds (broadleaf and grass) and by comparing it to weed-free plots. The preference of M. quadrilineatus for different cereal and weed species relative to carrots was tested in choice test assays. Habitat context influenced the abundance of M. quadrilineatus in the field experiments. The presence of border crops such as oat, rye, barley, wheat, and triticale did not significantly attract or repel this insect to carrot plots compared to the no-border treatment. However, spelt-bordered plots had 42% fewer M. quadrilineatus than three treatments, triticale, wheat, and barley, that had the highest insect abundance. The type of weed management affected M. quadrilineatus abundance in carrot plots, but not the frequency of herbicide application. Plots that had carrot growing with broadleaf-weeds had about 59% fewer M. quadrilineatus compared with those growing with crabgrass or carrot alone. In the greenhouse choice tests, grasses (e.g., cereals) attracted and broadleaf-weeds repelled M. quadrilineatus relative to carrots. In summary, carrot growers may be able to manage this pest by reducing the interaction of cereal cover crops with carrots and eliminating grassy weeds in commercial production fields.
  • Authors:
    • Shewry, P.
    • Tatham, A.
  • Source: Journal of Cereal Science
  • Volume: 55
  • Issue: 2
  • Year: 2012
  • Summary: The last review of the S-poor prolamins was published in 1995. Since then there has been a considerable increase in out knowledge of this interesting and unique group of proteins. The advances in the understanding of genetics and polymorphisms of the proteins are discussed including the available gene sequences and their alignments and consensus sequences. This group of prolamins are implicated as major allergens in WDEIA and wheat allergy and as immunodominant proteins in coeliac disease. The epitopes and their distribution throughout the protein sequences are reviewed. Their structure and physical chemistry is discussed in relation to their functional properties.
  • Authors:
    • Toth, T.
    • Arvay, J.
    • Tomas, J.
  • Source: Journal of Microbiology, Biotechnology and Food Sciences
  • Volume: 1
  • Issue: Special Issue
  • Year: 2012
  • Summary: The contents of heavy metals in plants were not in relation to contents of heavy metals in soil. Increased content of heavy metals in soils was not in consistency with content in plants. Usually content of heavy metals in plants according to our results were lower than their content in soil. Only the over limit contents of copper and cadmium were assessed in grain of barley and oat. The results of heavy metals content showed that dominant part on content of elements in plants have their mobile forms what depends on pH, content of organic matter in soil and portion of clay parts.
  • Authors:
    • Sturrock, C.
    • Korosak, D.
    • Samec, M.
    • Tester, M.
    • Davidson, R.
    • McNeill, A.
    • Roberts, J. A.
    • Black, C. R.
    • Tracy, S. R.
    • Mooney, S. J.
  • Source: PLANT AND SOIL
  • Volume: 353
  • Issue: 1-2
  • Year: 2012
  • Summary: Aims X-ray Micro Computed Tomography (CT) enables interactions between roots and soil to be visualised without disturbance. This study examined responses of root growth in three Triticum aestivum L. (wheat) cultivars to different levels of soil compaction (1.1 and 1.5 g cm(-3)). Methods Seedlings were scanned 2, 5 and 12 days after germination (DAG) and the images were analysed using novel root tracking software, RootViz3D (R), to provide accurate visualisation of root architecture. RootViz3D (R) proved more successful in segmenting roots from the greyscale images than semi-automated segmentation, especially for finer roots, by combining measurements of pixel greyscale values with a probability approach to identify roots. Results Root density was greater in soil compacted at 1.5 g cm(-3) than at 1.1 gcm(-3) (P=0.04). This effect may have resulted from improved contact between roots and surrounding soil. Root diameter was greater in soil at a high bulk density (P=0.006) but overall root length was reduced (P=0.20). Soil porosity increased with time (P<0.001) in the uncompacted treatment. Conclusions RootViz3D (R) root tracking software in X-ray CT studies provided accurate, non-destructive and automated three dimensional quantification of root systems that has many applications for improving understanding on root-soil interactions.
  • Authors:
    • Caesar, A.
    • Caesar-TonThat, T.
    • Sainju, U. M.
  • Source: Soil and Tillage Research
  • Volume: 118
  • Issue: January
  • Year: 2012
  • Summary: Portable chamber provides simple, rapid, and inexpensive measurement of soil CO2 flux but its effectiveness and precision compared with the static chamber in various soil and management practices is little known. Soil CO2 flux measured by a portable chamber using infrared analyzer was compared with a static chamber using gas chromatograph in various management practices from May to October 2008 in loam soil (Luvisols) in eastern Montana and in sandy loam soil (Kastanozems) in western North Dakota, USA. Management practices include combinations of tillage, cropping sequence, and N fertilization in loam and irrigation, tillage, crop rotation, and N fertilization in sandy loam. It was hypothesized that the portable chamber would measure CO2 flux similar to that measured by the static chamber, regardless of soil types and management practices. In both soils, CO2 flux peaked during the summer following substantial precipitation and/or irrigation (>15 mm), regardless of treatments and measurement methods. The flux varied with measurement dates more in the portable than in the static chamber. In loam, CO2 flux was 14-87% greater in the portable than in the static chamber from July to mid-August but 15-68% greater in the static than in the portable chamber from late August to October in all management practices. In sandy loam, CO2 flux was 10-229% greater in the portable than in the static chamber at all measurement dates in all treatments. Average CO2 flux across treatments and measurement dates was 9% lower in loam but 84% greater in sandy loam in the portable than in the static chamber. The CO2 fluxes in the portable and static chambers were linearly to exponentially related (R-2 = 0.68-0.70, P < 0.01, n = 40-56). Although the trends of CO2 fluxes with treatments and measurement dates were similar in both methods, the flux varied with the methods in various soil types. Measurement of soil CO2 flux by the portable chamber agreed more closely with the static chamber within 0-10 kg C ha(-1) d(-1) in loam soil under dryland than in sandy loam soil under irrigated and non-irrigated cropping systems. Published by Elsevier B.V.
  • Authors:
    • Barsotti, J. L.
    • Lenssen, A. W.
    • Caesar-TonThat, T.
    • Sainju, U. M.
  • Source: Soil Science Society of America Journal
  • Volume: 76
  • Issue: 5
  • Year: 2012
  • Summary: Information is needed to mitigate dryland soil greenhouse gas (GHG) emissions by using novel management practices. We evaluated the effects of cropping sequence and N fertilization on dryland soil temperature and water content at the 0- to 15-cm depth and surface CO2, N2O, and CH4 fluxes in a Williams loam (fine-loamy, mixed, superactive, frigid, Typic Argiustolls) in eastern Montana. Treatments were no-tilled continuous malt barley (Hordeum vulgaris L.) (NTCB), no-tilled malt barley-pea (Pisum sativum L.) (NTB-P), and conventional-tilled malt barley-fallow (CTB-F) (control), each with 0 and 80 kg N ha(-1). Gas fluxes were measured at 3 to 14 d intervals using static, vented chambers from March to November 2008 to 2011. Soil temperature varied but water content was greater in CTB-F than in other treatments. The GHG fluxes varied with date of sampling, peaking immediately after substantial precipitation (>15 mm) and N fertilization during increased soil temperature. Total CO2 flux from March to November was greater in NTCB and NTB-P with 80 kg N ha(-1) than in other treatments from 2008 to 2010. Total N2O flux was greater in NTCB with 0 kg N ha(-1) and in NTB-P with 80 kg N ha(-1) than in other treatments in 2008 and 2011. Total CH4 uptake was greater with 80 than with 0 kg N ha(-1) in NTCB in 2009 and 2011. Because of intermediate level of CO2 equivalent of GHG emissions and known favorable effect on malt barley yield, NTB-P with 0 kg N ha(-1) might mitigate GHG emissions and sustain crop yields compared to other treatments in eastern Montana. For accounting global warming potential of management practices, however, additional information on soil C dynamics and CO2 associated with production inputs and machinery use are needed.
  • Authors:
    • Liebig, M. A.
    • Caesar-TonThat, T.
    • Stevens, W. B.
    • Sainju, U. M.
  • Source: Journal of Environmental Quality
  • Volume: 41
  • Issue: 6
  • Year: 2012
  • Summary: Management practices, such as irrigation, tillage, cropping system, and N fertilization, may influence soil greenhouse gas (GHG) emissions. We quantified the effects of irrigation, tillage, crop rotation, and N fertilization on soil CO2, N2O, and CH4 emissions from March to November, 2008 to 2011 in a Lihen sandy loam in western North Dakota. Treatments were two irrigation practices (irrigated and nonirrigated) and five cropping systems (conventional-tilled malt barley [Hordeum vulgaris L.] with N fertilizer [CT-N], conventional-tilled malt barley with no N fertilizer [CT-C], no-tilled malt barley pea [Pisum sativum L.] with N fertilizer [NT-PN], no-tilled malt barley with N fertilizer [NT-N], and no-tilled malt barley with no N fertilizer [NT-C]). The GHG fluxes varied with date of sampling and peaked immediately after precipitation, irrigation, and/or N fertilization events during increased soil temperature. Both CO2 and N2O fluxes were greater in CT-N under the irrigated condition, but CH4 uptake was greater in NT-PN under the nonirrigated condition than in other treatments. Although tillage and N fertilization increased CO2 and N2O fluxes by 8 to 30%, N fertilization and monocropping reduced CH, uptake by 39 to 40%. The NT-PN, regardless of irrigation, might mitigate GHG emissions by reducing CO2 and N2O emissions and increasing CH4 uptake relative to other treatments. To account for global warming potential for such a practice, information on productions associated with CO2 emissions along with N2O and CH4 fluxes is needed.
  • Authors:
    • Bakken, L.
    • Budai, A.
    • Chen, R.
    • Senbayram, M.
    • Dittert, K.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 147
  • Issue: January
  • Year: 2012
  • Summary: Amending agricultural soils with organic residues is frequently recommended to improve soil fertility and to sequester carbon for counteracting global warming. However, such amendments will enhance microbial respiration, hence denitrification. Therefore, the assessment of effects on global warming must take N2O emission and the N2O/(N2O + N-2) product ratio of denitrification into account. There are some indications that the product ratio of denitrification is positively correlated with the ratio of available NO3- and available organic C in soils, but more research is needed to unravel quantitative relationships in well defined experiments. We conducted two laboratory incubation experiments, with the objective (i) to test the impact of the application of various N containing organic substrates including biogas residue on the denitrification rate and on N2O emission, and (ii) to investigate the effect of various NO3- concentrations on the denitrification rate and the N2O/(N2O + N-2) product ratio under standardized anoxic conditions in soils collected from long-term organic or inorganic fertilizer plots. In experiment 1, we found that biogas residue was more recalcitrant than maize straw, despite a high concentration of soluble organic C. High respiration (treatments with maize straw and sucrose) resulted in a transient peak in N2O emission, declining rapidly towards zero as nitrate concentrations reached less than 20 mg NO3--N kg(-1) dry soil. Application of biogas residue had a more moderate effect on soil respiration and denitrification, and resulted in a more long lasting peak in N2O emission. The results were interpreted as a result of a gradual increase in the relative activity of N2O reductase (thus lowering of the N2O/(N2O + N-2) product ratio of denitrification) throughout the incubation, most likely controlled by concentration of available NO3- in soil. In the second experiment, we found low N2O/(N2O N-2) product ratios for the treatment where NO3- concentrations were = 10 mM NO3-, and the ratios were remarkably independent of the soil's fertilizer history. We conclude that (i) in N-fertilized agricultural soils, application of organic matter with high contents of labile C may trigger denitrification-derived N2O emission whereas (ii) in soils with low NO3- contents such application may substantially lower the N2O/(N2O + N-2) product ratio and hence N2O emission. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Walker, M. B.
    • Faber, A.
    • Syp, A.
  • Source: Journal of Food, Agriculture & Environment
  • Volume: 10
  • Issue: 3-4
  • Year: 2012
  • Summary: In this paper, simulations with a Denitrification -Decomposition (DNDC) model were used to evaluate the impact of different management options on carbon (C) sequestration and emission of greenhouse gases: methane (CH 4) and nitrous oxide (N2O). Two cropping systems were analyzed. The first included potato, winter wheat, spring barley and forage maize (P-W-B-M). The second included potato, winter wheat, spring barley with clover and grass mixture (P-W-B-C). In both cropping systems, different farmyard manure (FYM) rates were applied. The application of additional nitrogen (N) using FYM increased the C sequestration, as well as N2O emissions and had a little effect on CH 4 uptake. An estimate into the average annual increases in N2O emissions, which were converted into carbon dioxide (CO2) equivalent emissions with 100-year global warming potential (GWP) multipliers, were offset by 56-144% of the C sequestration, depending on the management option. After 16 years of the experiment, the accumulation of C and N per hectare increased in the soil organic matter (SOM) pool. In P-W-B-M rotation, with manure applied at 325 kg N ha(-1), the accumulation of C increased to 5,760 and N 585 kg ha(-1), respectively. In P-W-B-C rotation, where a higher rate of manure was applied, the increase of C was at 10,796 and N 740 kg ha(-1). The highest influence in the rise of C and N accumulation was in humates. The high value of C sequestration in soil outweighs the emissions of N2O. In P-W-B-M rotations, the rate of applied FYM switched its average annual net GWP balance from net losses to a net sink. In P-W-B-C rotations, the applied FYM increased the annual rate of GHG emissions by 3%. The average annual N2O emissions increased by 44% under P-W-B-C rotation and by 142% under P-W-B-M rotations. Increases in the soil organic carbon (SOC) were by 234% and 408%, respectively, for P-W-B-C and P-W-B-M rotations. Our study showed that usage of FYM should be managed correctly, because applications at high rates have a negative impact on environment.
  • Authors:
    • Fitt, B. D. L.
    • Stevens, M.
    • Townsend, J. A.
    • West, J. S.
  • Source: European Journal of Plant Pathology
  • Volume: 133
  • Issue: 1
  • Year: 2012
  • Summary: This review describes environmental factors that influence severity of crop disease epidemics, especially in the UK and north-west Europe, in order to assess the effects of climate change on crop growth and yield and severity of disease epidemics. While work on some diseases, such as phoma stem canker of oilseed rape and fusarium ear blight of wheat, that combine crop growth, disease development and climate change models is described in detail, climate-change projections and predictions of the resulting biotic responses to them are complex to predict and detailed models linking climate, crop growth and disease development are not available for many crop-pathogen systems. This review uses a novel approach of comparing pathogen biology according to 'ecotype' (a categorization based on aspects such as epidemic type, dissemination method and infection biology), guided by detailed disease progress models where available to identify potential future research priorities for disease control. Consequences of projected climate change are assessed for factors driving elements of disease cycles of fungal pathogens (nine important pathogens are assessed in detail), viruses, bacteria and phytoplasmas. Other diseases classified according to 'ecotypes' were reviewed and likely changes in their severity used to guide comparable diseases about which less information is available. Both direct and indirect effects of climate change are discussed, with an emphasis on examples from the UK, and considered in the context of other factors that influence diseases and particularly emergence of new diseases, such as changes to farm practices and introductions of exotic material and effects of other environment changes such as elevated CO2. Good crop disease control will contribute to climate change mitigation by decreasing greenhouse gas emissions from agriculture while sustaining production. Strategies for adaptation to climate change are needed to maintain disease control and crop yields in north-west Europe.