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31.
Increased atmospheric deposition of strong acids and deposition of potentially acidifying compounds (e.g. ammonium) has caused a decline in pH and exchangeable base cations in forest soils in Sweden. In recent years, attention has been paid to liming of forest soil as a method to counteract the effects of acid deposition. Experiments with liming, fertilization and woodash treatment of acid forest soils started in 1984. The aim of this study was to determine the effects of low doses of lime (500 to 1500 kg ha?1) in combination with N fertilizers on tree growth, nutritional status of trees as well as soil, and runoff chemistry. This paper describes the short term effects of liming and fertilization on runoff from ten small catchments in two regions in south Sweden. The effects of liming were small in both areas. In the catchments fertilized with N (NH4NO3), a substantial leakage of various N species appeared in runoff after treatment. The increased N output was dominated by nitrate. The excess leakage of N during 2 yr after fertilization was 25 and 13% as an average of the applied N in the two study areas. The mobile nitrate increased the base cations output via runoff with 10 to 100% during 1 yr after N treatment. The runoff of Al increased with 60 to 100% the first year in the fertilized catchments. Mobilization of cations was also influenced by ammonium, especially K that was exchanged by ammonium on the surface of the soil particles. The effects of woodash-treatment were small, however, sulfate in the ash leaked out following application and about 100% of the added sulfate was found in runoff during the first year. 相似文献
32.
Margit Olle Pille Sooväli 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2020,70(7):572-577
ABSTRACT Little research has been published about the occurrence of diseases in faba bean such as chocolate spot, ascochyta blight, or rust in Northern Europe. There is also little data about the impact of sowing rate or variety on disease development. Therefore, the purpose of this study was to assess the impact of variety and seeding rate on disease severity at Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie (BBCH) 75 (which is when 50% of pods have reached full length). Five varieties were tested from multiple Northern European countries: Bauska (Latvia), Jõgeva (Estonia), Gloria (Sweden), Julia (Sweden) and Lielplatones (Latvia). Two sowing rates were used: 30 seeds m-2 (100%) and 36 seeds m-2 (120%). The sowing rate did not influence disease severity. The varieties which were most damaged by chocolate spot were Gloria and Jõgeva and the varieties least damaged were Julia and Lielplatones. Variety did not influence the severity of ascochyta blight. The variety most damaged by rust was Gloria and the variety least damaged was Julia. The varieties most susceptible to disease Gloria and Jõgeva while Julia was least susceptible. Thus, Julia can be recommended for faba bean production in Northern Europe. 相似文献
33.
The aim of this study was to use finite element modeling (FEM) as a tool to analyze microwave scattering in wood and to verify
the model by measurements with a microwave scanner. A medical computed tomography scanner was used to measure distribution
of density and moisture content in a piece of Scots pine (Pinus sylvestris). Dielectric properties were calculated from measured values for cross sections from the piece and used in the model. Images
describing the distribution of the electric field and phase shift were obtained from the FEM simulation. The model was verified
by measurements with a scanner based on a microwave sensor. The results show that simulated values correspond well to measured
values. Furthermore, discontinuities in the material caused scattering in both the measured and the simulated values. The
greater the discontinuity in the material, the greater was the need for computational power in the simulation. 相似文献
34.
35.
Dinnebier RE Gunnarsson O Brumm H Koch E Stephens PW Huq A Jansen M 《Science (New York, N.Y.)》2002,296(5565):109-113
CHCl3 and CHBr3 intercalated C60 have attracted particular interest after a superconductivity transition temperature (Tc) of up to 117 K was discovered. We have determined the structure using synchrotron x-ray powder-diffraction and found that the expansion of the lattice mainly takes place in one dimension (triclinic b axis), leaving planes of C60 molecules on an approximately hexagonal, slightly expanded lattice. We have performed tight-binding band structure calculations for the surface layer. In spite of the slight expansion of the layers, for the range of dopings where a large Tc has been observed, the density of states at the Fermi energy is smaller for C60.2CHCl3 and C60.2CHBr3 than for C60. This suggests that the lattice expansion alone cannot explain the increase of Tc. 相似文献
36.
SummaryThis review aims to describe the nature of effective microorganisms (EM) and how EM influence the growth, yield, quality, and protection of vegetable plants. EM comprise a mixture of live natural cultures of microorganisms isolated from fertile soils that are used to improve crop production. EM technology was developed over 40 years ago by Dr. Tero Higa in Japan. How EM act and interact in the soil-plant environment to suppress plant pathogens and disease, to conserve energy, to solubilise soil minerals, to aid the balance and ecology of soil microbes, and to improve photosynthetic efficiency and biological nitrogen fixation are described. In 70% of published studies, it was concluded that EM had a positive effect on the growth of vegetables, while, in the other 30%, they had no significant influence. In this investigation, among 22 reports on the effects of EM on the yields of vegetables, 84% were positive, 4% were negative, and 12% showed no significant influence. It is concluded that EM can improve the quality and yield of vegetables by reducing the incidence of pests and diseases, and by protecting against weeds, thereby contributing to sustainable agriculture. 相似文献
37.
Ryne C Ekeberg M Jonzén N Oehlschlager C Löfstedt C Anderbrant O 《Pest management science》2006,62(10):912-918
Pheromone-based mating disruption of the almond moth (Ephestia cautella) (Walk.) (Lepidoptera: Pyralidae) was carried out in a chocolate factory in Sweden. Population monitoring was conducted with pheromone-baited traps and water traps. Pheromone traps showed a 94% catch reduction, and monitoring with water traps showed a significant decrease in total catch (5.0 and 1.6 individuals per trap per week before and during treatment respectively). The significance of the results was tested by fitting the observed data to a first-order autoregressive model. This made it possible to test the data with a 95% confidence interval, comparing trap catches before mating disruption treatment with trapping data during the experiment. It is suggested that this statistical approach may be used more frequently in mating disruption experiments where it is extremely difficult to control external factors and therefore equally difficult to use a comparable control plot to evaluate the treatment. 相似文献
38.
Pulsed field gradient NMR spectroscopy was used to determine the poly(ethylene glycol) (PEG) self-diffusion coefficient (D(PEG)) as a function of NaCl concentration (C(NaCl)) and denaturation time (t(D)) in whey protein solutions and gels. D(PEG) in the gel decreased with increasing C(NaCl) concentrations and increased with increasing t(D); the increase ceased for all PEGs when the gel was fixed. This increase was more pronounced for the 82250 g/mol PEG than the 1080 g/mol PEG. Moreover, the diffusion coefficient of nonaggregated whey protein was measured and an increase for longer t(D) was also observed. Scanning electron microscopy images and (1)H spectra demonstrated that D(PEG) were related to the structure changes and to the percentage of beta-lactoglobulin denaturation. 相似文献
39.
SummaryThe aim of this study was to provide an overview of the causes and control of calcium (Ca)-deficiency disorders in vegetables. Ca-deficiency is usually related to the inability of the plant to translocate adequate Ca to the affected part. Many vegetables develop unique symptoms: for example blackheart in celery, tipburn in lettuce, chervil, onion, fennel, chinese cabbage and other cabbages, blossom end rot (BER) in tomato. Ca-deficiency disorders in vegetables can be controlled by various means. The growing medium influences the development of Ca-deficiency symptoms in plants. Restriction of the root volume is one factor that favours the development of Ca-deficiency symptoms in leafy vegetables, but reduces the incidence of BER in pepper. Ca-deficiency can also be avoided by using reasonable levels of nitrogen in the nutrient solution. Cations depress Ca-uptake and distribution, while anions depress the development of tipburn in plants. Ca-deficiency can be avoided by using the recommended level of salinity for each crop. Too high a salinity level increases the symptoms of Ca-deficiency in plants. Watering helps to prevent Ca-deficiency injury, as when growing vegetables outdoors. Maintaining an optimum soil moisture level helps to promote adequate movement of Ca to the roots and into the plant. A low relative humidity during the day-time increases the Ca-contents of leaves in leafy vegetables with an open growing point, but reduces the Ca contents of fruit and the inner leaves of leafy vegetables with a closed growing point. Avoiding too long a duration of supplementary lighting, too high a light intensity, and the use of high-pressure sodium lamps can prevent Ca-deficiency injury in plants. Shading may influence the incidence of BER, by reducing the appearance of symptoms of BER. Growing plants under a far-red wavelength filter helps to prevent Ca-deficiency disorders. Avoiding high or low temperatures also prevents Ca-deficiency injury. A negative DIF value (DIF = the difference between the day-time and night-time temperatures; a negative DIF means the night temperature is higher than the day temperature) may influence the incidence of tipburn injury by reducing its appearance. Air flow to the affected parts of plants can help to avoid the symptoms of Ca-deficiency. Ca sprays also help to prevent Ca-deficiency disorders in plants. Mulches can be used to protect plants against Ca-deficiency. Some crop varieties are less susceptible to Ca-deficiency. The plant growth regulator, Cultar (paclobutrazol, an inhibitor of gibberellin-biosynthesis), may influence the symptoms of Ca-deficiency in plants by reducing the appearance of the disorders. Planting a little later than the optimum date can avoid Ca-deficiency symptoms in leafy vegetables in Nordic countries. Harvesting a little earlier than the optimum date can also avoid Ca deficiency- symptoms in leafy vegetables. 相似文献
40.
Mariette F Topgaard D Jönsson B Soderman O 《Journal of agricultural and food chemistry》2002,50(15):4295-4302
The self-diffusion coefficients of water in casein solutions and gels were measured using a pulsed-gradient spin-echo nuclear magnetic resonance technique (PGSE NMR). The dependence of the self-diffusion coefficient of water on the concentration and structure of casein is reported. The results were analyzed using a cell model. It was found that the water self-diffusion coefficient is insensitive to the structure of the casein in solution or in a gelled state. The influence of casein concentration on the water self-diffusion coefficient could be explained by obstruction from the casein molecule. Assuming a simple model with two water regions, each characterized by a specific water concentration and value of the water diffusion coefficient, the water mobility reduction induced by the casein can be rationalized. 相似文献