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111.
112.
Rahel Sutterlütti Manfred Kayser Martin Komainda Johannes Isselstein 《Grass and Forage Science》2023,78(3):402-415
Trees alter microclimate and radiation budget in alley cropping systems, which in turn change physiological processes of the grassland component. The influence of the trees on grassland growth depends on the climate zone as well as possibly on weather conditions during the respective growth interval. The proportion of shade-tolerant species in the grassland further modifies the tree effect on grassland growth, as well as the number of annual harvests. We studied the effect of distance and orientation relative to the tree line (tree line in the South-West vs. North-East) on growth rates of the adjacent grassland with two cutting frequencies (frequent vs. infrequent) in an alley cropping system with grassland of two different vegetation compositions (diverse vs. grass-clover) and willow clones. Microclimate parameters and radiation were measured at the points where growth rates were determined to better characterize the effect of position relative to the tree line. Growth rates differed significantly (p < 0.05) depending on the distance to the trees and annual biomass accumulation amounted to 389 ± 13.5 g m−2 in the center vs. 321 ± 10.0 g m−2 with trees in the North-East vs. 292 ± 9.2 g m−2 with trees in the South-West of the transect position. Lower growth rates occurred at positions with lower light quantities close to the trees, namely the position with the trees adjacent in the South-West. Temperature and relative humidity differences between the distances were significantly (p < 0.05) affected by distance to the tree line, but differences in neither soil nor air temperatures between the distances affected growth rates. Vegetation composition mediates the influence of the trees: the difference between positions was more pronounced in the diverse vegetation composition with higher productivities in the center between the alleys, but also with higher overall sward productivity. 相似文献
113.
研究了华中神农架自然保护区毛金竹(Phyllostachys nigra var. henonis (Mitford) Stapf. ex Rendle) 从发笋到成竹的营养生长行为。竹笋在5 月份出土,在16 天的发笋期内平均密度达到2.7 笋/m2。大约32% 的新笋死亡。昆虫损害、萎焉死亡、鼠类摄食分别占竹笋死亡总量的57%,29%和14%。5–6 月份,竹笋在34 天的升高期内长到400 ±23 cm 的高度,日增高1–56 cm。7–8 月份为发枝期,在此期间枝叶展开、竹竿发育定形。竹笋产量与立地成竹的密度正相关,而与立地草本层的高度负相关。图4 表3 参46。 相似文献
114.
Zofia Sokoowska Mieczysaw Hajnos Christian Hoffmann Manfred Renger Stefan Sokoowski 《植物养料与土壤学杂志》2001,164(5):591-599
The values of the surface fractal dimensions were determined for several samples of Cambisols and Luvisols from analysis of nitrogen and water vapor adsorption isotherms and from mercury intrusion data. Moreover, the values of fractal dimension characterizing the particle size distributions of soil samples were calculated by using a number‐based method. For almost all investigated soils the values of the surface fractal dimension, obtained from water vapor isotherms were lower than those obtained from nitrogen isotherms. Largest were the surface fractal dimensions evaluated form mercury intrusion data. No significant correlations between different kinds of surface fractal dimensions were found, and the reasons of this finding are discussed. However, the values of the surface fractal dimensions calculated from mercury intrusion data correlate with those characterizing the texture of soils. The paper also reports on correlations between of the values of surface area, fractal dimensions and some selected physico‐chemical characteristics of soils. 相似文献
115.
Phosphorus uptake by plant roots and arbuscular mycorrhizae (AM) hyphae can be described based on morphological and physiological uptake characteristics and parameters affecting P transport in the soil to the uptake surface. The current study aimed to quantify the relative contribution of hyphae and roots to P uptake of onion and to investigate the associated mechanisms using a mechanistic simulation model. Onion was grown in a growth chamber under controlled conditions at five levels of P supply with (M) or without (NM) AM. Uptake by onion roots and AM hyphae was simulated separately using a nutrient‐uptake model, which was developed for roots. Model parameters describing P transport in the soil, as well as morphological and physiological uptake characteristics of roots and hyphae were derived from soil and nutrient‐solution experiments. The model fairly described P uptake of M and NM plants at the highest level of P supply (28 µM P in soil solution) where roots and hyphae contributed nearly equally to P uptake of M plants. However, at lower P levels (≤0.41 µM P), hyphae accounted for nearly the whole P uptake whereas roots hardly explained any uptake. The effectiveness of AM hyphae at low P supply was well explained by their favorable morphological and physiological uptake properties. Hyphae were characterized by a diameter of 3 × 10–4 cm, a Km of 0.25 µM, and a Cmin of 0.04 µM, values that are about 200, 40, and 10 times lower, respectively, compared to those of roots. Not more than 60% of the uptake at lower levels of P supply could be explained by the sum of predicted uptake of roots and hyphae suggesting that hyphae and roots may have used mechanisms additional to those described by the model to mobilize P. This work demonstrated that mechanistic models can be useful tools to study the role of AM in P uptake of plants, although reliable estimation of model parameters, especially physiological uptake properties of AM, is still limiting this approach. 相似文献
116.
E. Leidinger E. Kramberger-Kaplan Manfred Gemeiner 《Comparative immunology, microbiology and infectious diseases》1993,16(4):289-298
Feline splenocytes were fused to the murine myeloma lines NSO or Ag8. Autologous serum and taurine were used as media supplements for the cat × mouse heterohybridomas. The best results were obtained by the use of NSO as fusion line with taurine-supported media. 相似文献
117.
M. Schwerin G. Warnat D. Giehm H. Wolf P.D. Thomsen 《Reproduction in domestic animals》1991,26(2):70-74
A method of simultaneous amplification at three different loci (Y-specific DNA, kappa-casein gene, growth hormone gene) in cattle is presented. The use of this procedure for genetic typing on bovine crude DNA samples from less than ten diploid cells is shown. The application of this method for embryo genotyping and animal breeding is discussed. 相似文献
118.
Broll S Kietzmann M Bettin U Kreienbrock L 《Berliner und Münchener tier?rztliche Wochenschrift》2004,117(9-10):392-397
An evaluation of production orders for medicated feedingstuffs for pigs given in 1998 in Schleswig-Holstein showed sulphonamides and combinations of sulphonamides and trimethoprim as frequently used antibiotical ingredients. The presented study analyses the production orders which include sulphonamides and combinations of sulphonamides and trimethoprim in more detail. There were large deviations to the rules of good clinical practise for the use of antibiotics. The applied dosage was often lower than suggested in the literature. 相似文献
119.
Broll S Kietzmann M Bettin U Kreienbrock L 《Berliner und Münchener tier?rztliche Wochenschrift》2004,117(9-10):387-391
An evaluation of production orders for medicated feedingstuffs for pigs given in 1998 in Schleswig-Holstein showed macrolides, lincomycin and tiamulin as frequently used antibiotical ingredients. The presented study analyses the production orders which include macrolides, lincomycin or tiamulin in more detail. There were large deviations to the rules of good clinical practise for the use of antibiotics (2000). The applied dosage was often lower than suggested in the literature. 相似文献
120.
Kietzmann M Böttner A Hafez HM Kehrenberg C Klarmann D Krabisch P Kühn T Luhofer G Richter A Schwarz S Traeder W Waldmann KH Wallmann J Werckenthin C;Arbeitsgruppe "Antibiotikaresistenz" der Deutschen Veterinärmedizinischen;Gesellschaft eV 《Berliner und Münchener tier?rztliche Wochenschrift》2004,117(3-4):81-87
In vitro susceptibility tests are performed to receive information for selecting the most suitable antibacterial agent. As result of in vitro susceptibility tests, the minimum inhibitory concentration (MIC) indicates bacteria as resistant or sensitive. To determine MIC, therapeutically relevant breakpoints have to be defined. Microbiological criteria, chemical and physical characteristics as well as pharmacokinetic and toxicological (tolerance) properties of the antimicrobial compounds have to be considered in the selection of the therapeutic agent in addition to clinical experiences. Using some concentration and time dependent antibiotics as examples, it is demonstrated that the above mentioned criteria are not sufficiently considered in currently defined breakpoints. 相似文献