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61.
Florian Wichern Elmar Eberhardt Jochen Mayer Rainer Georg Joergensen Torsten Müller 《Soil biology & biochemistry》2008,40(1):30-48
The objective of the present review was to present the current knowledge on nitrogen (N) rhizodeposition, including techniques for 15N labelling of agricultural plants, amounts of N rhizodeposition and its fate in soil. Rhizodeposition is the process of release of organic and inorganic compounds from living plant roots. It is often quantified in terms of carbon (C) and less often as N derived from rhizodeposition (NdfR). Rhizodeposition of N can be estimated by labelling plants with 15N and following its fate in soil. Most methods used for labelling plants with 15N can only be applied after appearance of the first leaf and only allow pulse or multiple pulse labelling. Only the split-root technique and the application of gaseous 15N allow continuous labelling. All methods available at present have their flaccidities mostly due to the fact that the application of N is not following its physiological pathway of assimilation or by using artificial conditions. In the studies reviewed, amounts of N rhizodeposits ranged from 4% to 71% of total assimilated plant N. In legumes the median was 16% and in cereals it was 14%. Rhizodeposits were 15–96% of the below-ground plant biomass (BGP). In legumes the median was 73% and in cereal it was 57%. The high variability of these results shows the need for more investigations on N rhizodeposition looking especially on the factors influencing the amounts released in different plant species under field conditions. 相似文献
62.
63.
Jonas Schler Dirk Hinrichs Georg Thaller 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2019,136(6):518-525
During last decades, native uniqueness decreased in local livestock breeds due to the introgression of high‐yielding breeds. Recovery of native uniqueness became important because of conservation aspects regarding native genetic diversity and native traits. Thereby the expectation exists, that the relation between native uniqueness and genetic gain is contradictory. The aim of this study was to explore the influence of native uniqueness on performance traits and the total merit index in a local red cattle breed from Northern Germany. Data contained a pedigree file of 178,255 Red Dual‐Purpose cattle, 809 target genotypes and 3,581 reference genotypes from introgressed breeds. Native genetic contributions were tested for correlation with performance traits of milk yield, longevity, foundation, somatic cells, fertility and maternal calving and the total merit index. The study revealed that native uniqueness is favourably related to longevity (0.16), foundation (0.23), and somatic cells (0.08), and the total merit index (0.10). Selection on native uniqueness could probably lead to an increased longevity, udder health and genetic gain of the Red Dual‐Purpose cattle. Moreover, it was shown that the Red Dual‐Purpose cattle was not upgraded through introgression of high‐yielding breeds. 相似文献
64.
Determination of the surface fractal dimension from sorption isotherms of five softwoods 总被引:6,自引:0,他引:6
Summary This paper presents the determination of the surface fractal dimensions from water adsorption/desorption data of five softwood
species by using three different methods. The Frenkel-Holsi-Hill model of polymolecular sorption on a fractal surface by allowing
capillary condensation is shown to be the best method. Using this method, the fractal dimensions were found to be close to
2.5 and 2.4 from desorption and adsorption isotherms respectively. Moreover, they were shown to slightly vary between species,
and between sapwood and heartwood for the temperature range of 30 to 60 °C, but with no clearly identifiable temperature effect.
Received 13 March 1997 相似文献
65.
Georg Husz 《植物养料与土壤学杂志》2001,164(1):71-75
The author proposes the extraction of mobile (”︁available”) ions including heavy metals by means of a 0.4 M solution of LiCl. The accuracy and precision of the method are demonstrated and the results compared with the CaCl2 and BaCl2 extraction. The suspension pH of non-calcareous samples remains almost constant during LiCl-extraction but changes considerably with NH4NO3- and NH4-acetate. The results of the LiCl- and the CaCl2-extraction were closely correlated. The same was true for the relative cation distribution on the sorption complex compared to the BaCl2-extraction. A series of arguments emphasize and substantiate the advantages of the use of neutral salts, especially LiCl, for extraction. 相似文献
66.
Finding suitable growth models for turbot (Scophthalmus maximus L.) in aquaculture 1 (length application)
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Vincent Lugert Jens Tetens Georg Thaller Carsten Schulz Joachim Krieter 《Aquaculture Research》2017,48(1):24-36
Growth data of two different commercial turbot (Scophthalmus maximus) strains reared in recirculating aquaculture systems were analysed with the aim to determine the most suitable model for turbot. To assess the model performance three different criteria were used: (1) The mean percentage deviation between the estimated length and actual length; (2) the residual standard error with corresponding degrees of freedom and (3) the Akaike information criterion. The analyses were carried out for each strain separately, for sexes within strains and for a pooled data set containing both strains and sexes. We tested a pre‐selection of six models, containing three to four parameters. Models were of monomolecular shape or sigmoid shape with a flexible point of inflection including the special case of monomolecular shape in defined cases of their parameters. The 4‐parametric Schnute model achieved best fit in 62% of all cases and criteria tested, followed by the also 4‐parametric generalized Michaelis–Menten equation in 48% and the 4‐parametric Janoschek model (38%). The von Bertalanffy growth function achieved only 29%, Brody 24% and a new flexible function 19% best fit. In a 1–1000 day growth‐simulation sigmoid shaped curves were produced by the Schnute model in 71% of cases. The Janoschek and the Michaelis–Menten model each produced sigmoid curves in 57% of all cases. This indicates that a flexible 4‐parametric function reflects the growth curve of turbot the best and that this curve is rather sigmoid than monomolecular shaped. 相似文献
67.
An incubation experiment was carried out to test the effects of biogenic municipal waste (compost I) and shrub/grass (compost II) composts in comparison to peat on respiration and microbial biomass in soil. The amounts of these three substrates added were linearly increased in the range of field application rates (0.5%, 1.0%, 1.5%, 2.0%). The sum of CO2 evolved during the incubation was markedly raised by the three substrates and increased with the rate of substrate concentration. However, the percentage of substrate mineralized to CO2 decreased with the addition rate from 103 to 56% for compost I, from 81 to 56% for compost II, and from 21 to 8% for peat. During the first 25 days of incubation, compost I enlarged the biomass C content, which remained constant until the end. In contrast, compost II did not raise biomass C initially. But at the end of the incubation, the biomass C content of all 4 compost II treatments almost reached the level of the respective compost I treatment. The increase was significantly larger the more of the two composts was added. In contrast to the two composts, the addition of peat did not have any significant effect on microbial biomass C. The average qCO2 values at day 25 declined in the order compost I > compost II > peat, at day 92 the order was changed to compost II > peat > compost 1. This change in the order was caused by a significant decrease in qCO2 values of the compost I treatments, a significant increase in qCO2 values of the peat treatments and constant qCO2 values in the compost II treatments. 相似文献
68.
69.
Dirk Hoffmeister Guido Waldhoff Wolfgang Korres Constanze Curdt Georg Bareth 《Precision Agriculture》2016,17(3):296-312
Information on crop height, crop growth and biomass distribution is important for crop management and environmental modelling. For the determination of these parameters, terrestrial laser scanning in combination with real-time kinematic GPS (RTK–GPS) measurements was conducted in a multi-temporal approach in two consecutive years within a single field. Therefore, a time-of-flight laser scanner was mounted on a tripod. For georeferencing of the point clouds, all eight to nine positions of the laser scanner and several reflective targets were measured by RTK–GPS. The surveys were carried out three to four times during the growing periods of 2008 (sugar-beet) and 2009 (mainly winter barley). Crop surface models were established for every survey date with a horizontal resolution of 1 m, which can be used to derive maps of plant height and plant growth. The detected crop heights were consistent with observations from panoramic images and manual measurements (R2 = 0.53, RMSE = 0.1 m). Topographic and soil parameters were used for statistical analysis of the detected variability of crop height and significant correlations were found. Regression analysis (R2 < 0.31) emphasized the uncertainty of basic relations between the selected parameters and crop height variability within one field. Likewise, these patterns compared with the normalized difference vegetation index (NDVI) derived from satellite imagery show only minor significant correlations (r < 0.44). 相似文献
70.
Sabin Basi Juergen Burkhardt Georg Noga Mauricio Hunsche 《Weed Biology and Management》2014,14(3):186-197
The objective of this study was to better understand the role of chaotropic and kosmotropic salts in stomatal uptake, a process that occurs in parallel with cuticular penetration and affects the bioefficacy of glyphosate. In Trial 1, salt solutions of kosmotropic (NH4)2SO4 and chaotropic NaClO3, with or without the organosilicone surfactant, Break‐Thru® S233 (BT), and with or without glyphosate, were prepared. In Trial 2, sodium salts with a kosmotropic‐to‐chaotropic nature (Na2SO4, NaCl, NaNO3 or NaClO3) and BT were prepared with or without glyphosate. At very high concentrations, the salts of a kosmotropic nature induced a slight decrease in the surface tension, whereas those of a chaotropic nature triggered a significant decrease in the surface tension. Solution droplets were deposited onto the leaves of Viola arvensis and Chenopodium album. The dried deposits were analyzed with an environmental scanning electron microscope. The salts formed structures linking the exterior to the interior of the stomata in the crystalline ([NH4]2SO4) or amorphous (NaClO3) form. However, the low surface tension alone did not appear to be the unique driving force for stomatal uptake. With glyphosate, amorphous globular structures of glyphosate salt were formed in the Na2SO4 (kosmotropic) solution. Differently, the salts of a rather chaotropic nature (NaNO3 or NaClO3) formed a colloidal matrix. In general, salt residues were observed over the periclinal cell walls and inside the stomatal chamber. Neither (NH4)2SO4 nor Na2SO4 had a significant impact on glyphosate bioefficacy. However, the chaotropic salt, NaNO3, enhanced the bioefficacy of glyphosate the most, with a performance that was comparable to that of the solution glyphosate + organosilicone surfactant. 相似文献