Erfassung von Humusprofilmerkmalen mit Hilfe von Anschliffen

Evaluation of humus profile parameters with the aid of polished blocks On polished blocks, humus profile parameters can be isolated optically and estimated quantitativly by stereological methods. The parameters are, above all, shoot residues, roots and root residues, droppings of enchytraeids and earth-worms, lobular pore edges, pores. By the estimation of those parameters, investigations of polished blocks can contribute to problems of ecology of humus profiles and sites as well as problems of humus systematics.     

Langstreckentransport von Calcium in Stolonen von Kartoffelpflanzen

Long-distance transport of calcium in stolons in potato plants In potato plants grown in water culture the influence of the tuber growth rate and the Ca supply to the tubers as well as the effect of the relative humidity around the stolons and tubers on the ⁴⁵Ca translocation in the stolon was investigated. If the stolon tip or the tuber were supplied with additional exogenous Ca and the relative humidity around the stolon or tuber was very high then ⁴⁵Ca applied to the roots was translocated in a negligible amount into the stolon or tuber. Even when the supply of exogenous Ca to the tubers was low, the tubers exerted no “sink”-effect on the ⁴⁵Ca translocation within the stolon. Under conditions of high relative humidity around the stolon ⁴⁵Ca applied to the stolon surface was nearly exclusively translocated in direction of the shoot. In contrast, under low relative humidity around the stolon or tuber ⁴⁵Ca applied to the stolon surface or to the root system was translocated into the stolon tip and into the tuber. The results indicate that within the stolon Ca is exclusively translocated in the xylem. A “sink”-effect of the tuber on the Ca translocation into the stolon as well as within the stolon was not been observed.     

葡萄糖代谢调控

葡萄糖氧化持续供给机体大量的能量。进食或禁食一段时间后,血糖水平保持相对稳定。激素在调节血糖浓度中起着重要的作用。本文主要阐述了葡萄糖在产生、转运以及利用过程中的调控。     

Einfluß von N-Lignin auf Wachstum und N-Stoffwechsel von Weizen-Zellsuspensionskulturen

The effects of N-Lignin on growth and N-metabolism in wheat cells in suspension cultures N-Lignin is an organic N-fertilizer which is synthesized from waste liquors of the pulp industry by oxydative ammonisation. Nearly 40% of its N-content is available as ammonium, the rest is linked in organic compounds. Water-soluble fractions of N-Lignin were added to the nutrient solutions of wheat cells in suspension cultures in order to study the effects on growth and N-metabolism. The experiments show that N-Lignin is a suitable nitrogen source for growing wheat cells. The best growth was achieved when 50% of the total nitrogen content of the medium were added as N-Lignin nitrogen. This mixture of N-Lignin and nitrate was even superior to the standard B-5-medium with respect to the final dry weight. However, higher concentrations of N-Lignin inhibited cell growth. The effect of N-Lignin on cell growth is not only influenced by ammonia. If wheat cells were grown on media with ammonium-N as the sole nitrogen source acids of the citrate cycle had to be added to support growth. This was not necessary with N-Lignin. N-Lignin therefore seems to effect the energy metabolism. High amounts of ammonium-N or the reduced N-fractions of N-Lignin respectively resulted in an increase of certain amino acids and especially of the two amides glutamine and asparagine. Furthermore root formation was observed with cells grown in media containing N-Lignin or ammonium-N. The root formation seemed to be correlated with added amounts of reduced nitrogen. Root formation was not observed with cell cultures incubated with N-Lignin solutions which were made free of ammonium-ions with a cation exchanger (Amberlite IR-120) loadad with potassium. This indicates that the differentiation of roots in the normally embryonic cells is due to the ammonium-N content of N-Lignin. A possible correlation between the content of glutamine and asparagine and the formation of roots is discussed.     

Einfluß von Ammonium- und Nitratstickstoff auf die Entwicklung von Buchenjungpflanzen

Influence of ammonium and nitrate nitrogen on the growth of young beech plants Young beech plants were grown in aerated nutrient solutions with NH₄ or NO₃ nitrogen for a period of 12 weeks. pH-changes caused by the source of nitrogen were corrected every second day. Absorption of NH₄-N was higher than of NO₃-N. NH₄-N was superior for shoot growth and development of lateral roots, NO₃-N for growth of the main root. Nutrient solution containing both sources of nitrogen was the most favorable.     

Einfluß von Silizium auf den Bindungszustand von Mangan im Blattgewebe von Bohnen (Phaseolus vulgaris)

Effect of silicon on the chemical state of manganese in bean leaf tissue (Phaseolus vulgaris L.) In water culture experiments with bean plants the effect of different manganese supply and of silicon on the chemical state of manganese in the leaf tissue has been studied. Water, KCl, EDTA and methanol have been used for extraction. Water extracted up to 80% of the total manganese from previously frozen or freeze dried leaf tissue. This water soluble fraction of manganese showed a positive correlation with manganese supply and leaf age. Silicon had no effect on the manganese extractable by water, KCl or EDTA. The high proportion of manganese in the water extract is probably the result of manganese oxides (MnO₂?) being dissolved during extraction by organic cell constituents e.g. organic acids. Therefore, in vivo less manganese is water soluble than the amount extractable with water. In contrast to water, methanol extrated less than 10% of the total manganese. Silicon supplied in the culture solution doubled the amount of manganese extracted from the leaves by methanol. This result suggest that by affecting the compartmentation of manganese silicon increases the soluble manganese in vivo, which could partly explain the increase in manganese tolerance of the leaf tissue in presence of silicon.     

Einfluß von Monoethanolamin auf Ertrag und Wasserausnutzung von Sommergerste

Effect of monoethanolamine on yield and water use efficiency of barley The effect of monoethanolamine (EA) on yield and water use efficiency (WUE) of spring barley plants was tested in pot experiments. The application of EA (8 to 12 mg/pot) increased the grain yield and WUE by about 4 to 15 per cent under stress conditions. In addition, EA improved the utilization of fertilizer nitrogen. The yield-increasing effect of EA was associated with an increase of the number of ear-bearing tillers and an improved root growth. The effects of EA were only significant at α = 0.05.     

Einfluß von Licht auf die Keimung von Kürbissamen

Zusammenfassung Der Einfluß von Licht auf die Keimung der Samen verschiedener Sorten und Herkünfte vonCucurbita pepo L. undCucurbita maxima Duch. wurde geprüft. Bis auf eine Herkunft aus Jugoslawien waren alle Formen vonCucurbita pepo L. sehr lichtunempfindlich, nur dunkelrote Strahlen verursachten eine Herabsetzung ihrer Keimkraft. Die Samen vonCucurbita maxima Duch. erwiesen sich als Dunkelkeimer. Weißes Licht hemmte ihre Keimung sehr stark, Dunkelrot unterdrückte sie vollkommen und Blaulicht hatte eine schwächere Hemmwirkung. Hellrot sowie Grün waren unschädlich. Eine Nachbehandlung der nicht gekeimten Samen mit Hellrot konnte ihre Keimung auslösen. Das Keimverhalten der Samen der untersuchten Sorten und Herkünfte vonCucurbita wird daher wohl im wesentlichen durch das von Borthwick und Hendricks beschriebene Phytochromsystem gesteuert.

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Summary The influence of light on the germination of seeds from different varieties and origins ofCucurbita pepo L. andCucurbita maxima Duch. was studied. All forms ofCucurbita peop L. (anorigin from Jugoslavia made an exception) were very insensitive against light, only dark-red radiation caused a depression of germination. The seeds ofCucurbita maxima Duch, were shown as darkgerminators. White light caused a strong depression, dark-red fully stoped germination, and blue light had smaller effects. Light-red as well as green had no damaging influence. Aftertreatment of the ungerminated seeds with light-red induced germination. After these results it seems that the germination of the investigated sorts and origins ofCucurbita is controlled by the phytochromsystem, described by Borthwick and Hendricks.

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am ¶rt;au Cucurbita pepo L. C. maxima Duch. , C. pepo , - ¶rt; . C. maxima . , , . - . — . , , , , , , .

     

Vergleich von Nitrat- und Amino-N-Schnelltest zur Charakterisierung des Stickstoff-Versorgungsgrades von Winterweizen

Comparison of the rapid tests for nitrate and amino-N for evaluating the N-status of winter wheat Nitrogen fertilizer trials with winter wheat were conducted in 1985 and 1986 to compare the efficacy of the rapid test for nitrate (in the stem base) and a newly developed rapid test for amino-N (in fully expanded green leaves) for evaluating the N-status of plants. In addition, the influence of weather conditions on the results given by both tests when using ammonium nitrate (NH₄NO₃ + CaCO₃) (AN) and urea-ammonium nitrate solution (UAN), was evaluated to determine wether the rapid test for amino-N gives more accurate information on the N-status of winter wheat than the rapid test for nitrate. The results show that the rapid test for nitrate is suitable to characterize the N-status of winter wheat when nitrogen is predominantly taken up by roots as nitrate. This is normaly the case when plants are fertilized with the salt form of nitrogen, als well as with liquid fertilizer, such as UAN applied through tubes in the soil, as for fertilization of winter wheat at later growing stages. However, during dry weather (1986 field trial) UAN application on leaves at shooting and ear emergence can result in high nitrogen uptake by leaves, causing an underestimation of plant N-status by the rapid test for nitrate, and thus, subsequent excess N-fertilizer application may be recommended (order of magnitude: 20 kg N/ha). Under these conditions the rapid test for amino-N in leaves (pressed sap) is a more accurate test for estimation of plant N-status because it determines glutamine and amino acids, the most important storage forms of reduced nitrogen in plants. When UAN fertilizer on leaves is washed off by rain (1985 field trial), crop N-fertilizer requirements predicted by both tests are comparable. If storage of nitrate in the stem base occurs, due, for example to low radiation intensity during spring (lower nitrate reduction), with the rapid test for amino-N an underestimation of plant N-status can be obtained.     

Aufnahme und Verlagerung von Natrium bei zwei Sorten von Lolium perenne

Uptake and translocation of sodium in two cultivars of Lolium perenne The uptake and translocation of Na was investigated in two Lolium perenne cultivars (Dolewi and NFG). With increasing Na⁺ concentration in the nutrient solution (0, 1, 2 and 4 mMNa) the Na⁺ uptake per pot increased from 1.4 to 11.9 me/1 Na⁺ for Dolewi and from 1.1 to 6.9 me/l Na⁺ for NFG. The higher Na uptake by Dolewi can only partly be explained by better growth, the higher Na⁺ selectivity playing also an important role. In another experiment plants of both types were grown in solution cultures for 41/2 weeks at 15°C and 25°C, respectively. Hereafter the plants were supplied with 1.25 mM ²⁴NaCl for six hours under equal conditions. Again the higher Na uptake and also a higher Na translocation (of about 20%) was found in Dolewi, whereas only 10% of the ²⁴Na uptake had been translocated by NFG. When plants were grown in a nutrient solution with a lower temperature (at 15°C) the root lipids showed a higher linolenic acid and oleic acid content than the plants grown in a medium at 25°C. At the same time the 24Na uptake was higher in the plants grown at the lower temperature, yet the relationship between root lipids and Na uptake still remains to be elucidated.     

Einfluss von Bodeneigenschaften auf die Segetalflora von Ackerflächen

Impact of soil properties on weed distribution within agricultural fields Occurrence and distribution of weeds on agricultural fields are often heterogenous. The influence of various soil properties on the spatial structure and density of weed populations was investigated on two agricultural fields with special regard to three weed species (Polygonum amphibium, Cirsium arvense, Veronica hederifolia). Based on field specific sampling grids, weed counting and soil sampling were done. For all grid points, soil analysis was carried out (texture, organic C, total N, pH, soil nutrients P, K, Mg). Soil texture, soil organic C, and soil nutrients are the factors with the highest influence on the occurrence of the species studied.     

Geometrische Interpolation von Saugspannungsverteilungen

A procedure for interpolating the depth distribution of soil moisture tension A programmable procedure is described to compute hydraulic gradients from soil moisture tensions non-linearly distributed with depth. This interpolation-technique is based upon a geometrical procedure. Compared with other curve smoothing techniques it is flexible with respect to the given data constellation and requires a relatively small computational effort. This method is compared with that of cubic splines.     

Verteilung von grenzabständen auf bodenkarten und ermittlung von risikofunktionen

Distributions of boundary spacings were analysed for different soil maps (1:25000, 1:5000) by a statistical procedure. The distributions of boundary spacings are satisfactorily described by negative exponential functions. Therefore, connections between mean boundary spacings, sampling interval and the risk of missing boundaries can be evaluated, and it is shown, that the connection between sampling interval and risk of missing boundaries is landscape specific.This results can be used for planning soil survey, particularly for special survey activities.     

Auswirkungen von Lockerungsmaßnahmen auf das Bodengefüge von Pseudogleyen

Effect of sub-soiling on the physical characteristics of pseudogleys. . Physical studies on eight soils that had been sub-soiled over a range from two to twelve years before, showed that after two years the loosening of the subsoil was still god. The soils that had been sub-soiled eight to twelve years before were only slightly better than the untreated ones. Available water capacity for plants could not be increased. On the other hand it was possible to decrease mechanical compactness of the soil and to cultivate the soil earlier in the year.     

Vergleich von zwei nicht-destruktiven Methoden zur Bestimmung von Wurzeloberflächen

Comparison of two non-destructive methods for determination of root surface areas In order to study root growth and development continuously in water culture experiments, two non-destructive rapid methods of estimating root surface area were compared. In the methylene blue method roots are stained for 30 seconds in methylene blue solution (74.7 mg/l). After washing off adhering methylene blue the adsorbed cationic dye is exchanged with Ca²⁺ by incubating the stained root in 0,1 M CaCl₂ solution. The amount of exchangeable methylene blue is determined photometrically at 668 nm. In the ink method, roots are stained for 1 minute with a 1:100 diluted solution of drawing ink. Excess ink is removed by carefully rotating the plant, and adhering ink is allowed to diffuse into destilled water. The quantity of ink is determined photometrically at 500 nm. The root surface area of potato plants estimated with these two methods correlates highly significantly with the root surface area calculated from root volume and root length. In the case of the ink method the calibration curve obtained with potato roots may also be used for other plant species like maize. This is not possible with the methylene blue method. A correction factor depending on the cation exchange capacity of the roots would be needed for this method. With the ink method overestimation of root surface area may occur if abundant root hairs are present. This is due to the formation of droplets in the root hair zone. However for repeated measurements during a growth period the ink method is more suitable since with this method no negative effect on root growth and nutrient uptake can be observed.