Der Einfluß von Dieselkraftstoff auf die Aggregatstabilität,den Plastizitätsindex und das Scherverhalten unterschiedlicher Bodenmaterialien

The effect of Diesel fuel on stability of aggregates, plasticity index and shear strength of two soil materials The influence of Diesel fuel contamination on mechanical properties of soil are investigated with regard to the retreatment of materials after a cleaning process. Following aspects are examined in laboratory tests: waterstability of aggregates, plasticity index and shear strength parameter. The used soil materials are mixed samples of a Luvisol (=Bt) and a tidal influenced alluvial clay sediment of a Gley (=Klei). The aggregate stability of Bt material is rising at increasing Diesel fuel contaminations due to a hydrophob effect on the surfaces of the aggregates. This influence cannot be shown for clay material. On the other hand the plasticity index shows a decrease for low Diesel fuel contaminations, because the Diesel fuel acts directly to the particle surfaces. At increasing contaminations these effects are overlayed by increasing viscosity and shear strength of water and Diesel fuel phases or emulsions. The increase in stability of aggregates is not evident in a shear box test. The Diesel fuel shows no influence to angle of internal friction for both investigated materials. On the other hand there is an effect to the cohesion. This phenomenon could be explicated with above mentioned increase in cohesion due to an increase in shear strength and viscosity of a two phase system.     

Einfluß von Ammonium- und Nitratstickstoff,Eisenchelaten und CCC auf den Chlorophyll- und Gesamtzukerghalt der Blätter chlorotischer,immergrüner Pflanzen auf alkalischen Böden Isfahans

Effect of ammonium and nitrate nitrogen, iron chelates and CCC on the chlorophyll and carbohydrat content in leaves of chlorotic, periwinkle plants an alkaline soils in Isfahan In pot experiments with periwinkle plants on alkaline soils the effect of nitrogen fertilization, iron chelats and cycocel in treating iron chlorosis was studied. High amounts of calcium nitrate produced chlorosis, followed by a general decrease in plant growth, while the same amount of ammonium sulfat prevent chlorosis and increased chlorophyll content and production of dry matter. In chlorotic plants both the chlorophyll and sugar content was increased by spraying with iron chelate, and with cycocel as well.     

Untersuchungen über den Einfluß des Kinetins und des Eisens auf den Nukleinsäure- und Proteinstoffwechsel von Karottengewebekulturen

The Influence of Kinetin and Iron on Nucleic Acid and Protein Metabolism of Carrot Tissue Cultures Carrot-root tissues cultured in a nutrient solution containing Kinetin had a high rate of cell division, that led to an undifferentiated callus, and a relatively low DNA content per cell. The same tissues growing without Kinetin had a smaller rate of cell division and a higher DNA content, and showed the ability to form roots. By addition of ³²P to the nutrient solution, the cultures growing with Kinetin showed a higher specific activity of DNA than those growing without Kinetin. From previous experiments and results of other workers the possibility of the occurence of a metabolic labile DNA fraction in the cultures which grew without Kinetin is discussed. A comparison between the influence of iron and Kinetin on cell division activity, root formation, DNA, RNA and amino acid content of the tissue cultures was made on a cell basis. Iron deficiency or absence of Kinetin in the nutrient solution reduced the cell division activity of carrot tissue cultures and increased the content of DNA, RNA and soluble amino acids. The protein content was reduced by iron deficiency but was increased by the absence of Kinetin. Cultures, growing without Kinetin were able to form roots, while those, growing in an iron deficient medium were unable to show the latter phenomenon.     

Einfluß von Fe-und Mn-Mangel auf den Kationen-und Anionengehalt von Mais und Sonnenblumen

Effect of Fe-and Mn-deficiency on the cation and anion content of maize and sunflower. 1. In sandculture experiments with maize and sunflower the influence of Fe-and Mn-deficiency on the concentration of inorganic ions and organic acids in the plants was studied. 2. Fe-deficiency increased in both maize and sunflower plants the excess of cations (C-A) and the amount of organic acids (SOS). In sunflower this reaction was less intensive than in previous experiments with younger plants. 3. Mn-deficiency did not lead to the same clear reaction in both plant species as in the case of Fe-deficiency, although in the later harvestings (C-A)-and (SØ)-values of the deficient plants increased. 4. In both plant species the cultivars with higher susceptibility to Fe-chlorosis did not differ in their reaction on Fe-or Mn-deficiency from the normal cultivars. 5. A specific reaction of the plants on either Fe-or Mn-deficiency in respect to their ion concentration could not be confirmed.     

Einfluß steigender Stickstoffgaben auf den Kupferernährungszustand von Getreide

Effect of increasing nitrogen fertilization on copper demand in cereals Pot experiments were conducted with wheat (2 experiments) and spring barley (1 experiment) in a peat soil. Four N and four Cu fertilizer levels were chosen in such a way that, based on grain yield, within each N level there was a Cu deficient and a Cu sufficient treatment. For sufficient Cu supply, Cu level in soil and plant increased with increasing N level. Critical Cu concentrations in aboveground biomass at shooting [μg (g dw)^?1] were 3.5 (lowest N level = N₁) to 7.5 (highest N level = N₄) for grain production of wheat and barley, but for aboveground biomass of wheat at shooting they were only 2.6 (N₁) to 5.8 (N₄). Based on critical Cu concentration at different N levels, critical Cu/N ratios were determined. These were independent from N level, indicating that Cu remobilization in the older leaves is unlikely even at N deficiency. The high critical Cu concentrations at high N levels may be explained by an increased immobilization of Cu. Under Cu deficient conditions, Cu concentration did not increase with increasing N level. However, under Cu sufficient conditions, N concentration and Cu concentration of the plant increased with increasing N level. The increasing Cu uptake with increasing N level may be explained by the release of amines into the root apoplast and the rhizosphere. Particularly under Cu sufficient conditions, these may mobilize Cu by formation of soluble Cu-amine complexes.     

Einfluß exogener und endogener Faktoren auf den Calciumgehalt von Paprika- und Bohnenfrüchten

Effect of external and internal factors on the calcium content of paprika and bean fruits In water culture experiments with paprika and bean plants the effect of Ca supply, transpiration and growth rate on the Ca content of the fruits has been studied. A 10-fold increase in Ca supply only slightly increased the Ca content. The Ca content of the paprika fruits was increased considerably at high transpiration rates of either the whole shoot or the single fruit. High transpiration also increased the Mg content but had no effect on the K content. In bean high transpiration rates only increased the Ca content in the early stages of fruit development. The ratio of Ca translocation versus water loss by transpiration sharply declined during fruit growth in both species. In paprika the highest ratio (μg Ca/ml) in the fruits corresponded with the ratio in the leaves. In bean fruits, however, this ratio distinctly exceeded that of fully developed leaves. At high transpiration rates of the shoot 20% of the Ca (⁴⁵Ca) injected into the fruit were translocated out of the fruit. At low transpiration rates of the shoot the corresponding value was below 1%. Most of all the growth rate of the fruits affected the Ca content. With increasing growth rate the Ca transport into the fruits was hardly altered which in turn led to a sharp decrease of the Ca content per unit dry weight. The results support the idea of the Ca transport into the fruit via the xylem. This Ca transport — i.e. also the Ca content of the fruit — is regulated and is also to be influenced by direct or indirect alterations of the water transport in the xylem.     

Einfluß von K-Ernährung und Mehltaubefall auf den N-Haushalt von Sommergerste während des Kornwachstums

Influence of K nutrition and mildew attack on N metabolism of spring barley during grain development Spring barley cv Aramir was grown in complete nutrient solutions containing 0,4 (K₁) and 4 me K/l (K₂) respectively. Half of the plants were sprayed regularly with a fungicide, the other half became naturally infected by mildew, Erysiphe graminis. Mildew attack was clearly visible in unsprayed plants, especially at K₁. Accordingly also grain yield was depressed by 18% (K₁) and 15% (K₂) compared to the controls. Better K nutrition reduced symptoms of mildew infection drastically and increased grain yield from 87 g/pot (K₁) to 169 g (K₂). Similar yield increases (106 to 199 g/pot) were obtained in the control plants, revealing that under the experimental conditions better K supply stimulated growth in general rather than inducing specific defense mechanism against the pathogen. The latter was hoped to be detectable by applying ¹⁵N-nitrogen during 3 days at anthesis. Although K₂ plants absorbed more ¹⁵N and incorporated more ¹⁵N into leaf protein, this cannot be considered as a K induced defense reaction. Instead due to lower grain yields in infected plants less proteolysis in the vegetative plant parts occured.     

Der Einfluß von Ancymidol und Ethrel auf den Gibberellinsäuregehalt (GA3) von Getreidepflanzen

Influence of Ancymidol and Ethrel on the synthesis of gibberellic acid (GA₃) in cereal plants. In pot experiments with oat, barley and rye both growth regulators Ancymidol and Ethrel considerably reduced the GA₃ content in the 3 plant species. Ancymidol was approximately 10 times more effective than Ethrel. This higher effectivity of Ancymidol on the GA₃ content and the different structure of the Ancymidol molecule compared to Ethrel makes it probable that Ancymidol inhibits the GA synthesis in a different way than Ethrel (or CCC). Although Ethrel was less effective in reducing the GA content it decreased the stalk length more than Ancymidol. It is concluded that Ethrel not only influences the GA induced growth but also other processes which regulate the length growth of plants.     

Einfluß von Bodeneigenschaften,Bodennutzung und Bodentemperatur auf die N-Mobilisierung von Kulturböden

Influence of soil characteristics, agricultural use and soil temperature on the N-mobilization of cultivated soils A new N-mobilization model, which considers also the short term and seasonal N-supplying capacity of soil is presented. At a fixed time the potential mobilizable N (N-MOB) is a sum of difficultly mobilizable N (N-MOB_s) originating from the pool of difficultly mobilizable N (N_s) and the easily mobilizable N (N-MOB₁) originating from the pool of easily mobilizable N (N₁). It is possible to characterize soil according to their M₁, N-MOB_s and v (N-MOB_s per day) values. Usefulness of these parameters in N-nutrition and ground water burden from N has been discussed. Basic parameters of this model have been experimentally determined independently with the help of two different experiments i. e. laboratory incubation and column lysimeter using surface soil samples. The easily mobilizable N pool (N₁) values were found in the range of 142 to 814 kg N ha^?1 which corresponded to 1.2 to 7.4 % of organic N content of these soils. The difficultly mobilizable N per day (i. e. v = N-MOB_s per day) in an incubation experiment (35°C) were found in the range of 1.5 to 24kg N ha^?1. However, in the column lysimeter experiment, in contrast, these values at 10°C ranged between 0.05 to 0.9 kg N ha^?1. These values correspond to N-MOB_s values in the range of 11–182 kg N·ha^?1 for a period of 200 days which approximate to a vegetation period. For practical purposes, the N₁ and v values could be calculated by just measuring 3–4 points after 14 days of incubation at 35°C. The results show that N-MOB_s values strongly correlated compared to N₁ values to total N, organic carbon and clay content and non significantly to pH and silt content. The results of an laboratory incubation experiment carried out to assess the effect of temperature on N-mobilization show that even at 0°C there was N-mobilization. The results revealed that in the temperature range of 0–8°C (a range of soil temp. usually observed in winter months) and in the range of 25–40°C (range of summer months temp. for surface arable soil), a small change in the soil temperature would result in enormous increase in the quantity of mobilized N. The highest mobilized N quantity was found above 60°C.     

Einfluß von Stroh und Nitrapyrin auf den verfügbaren Stickstoff im Boden,den Ertrag und den Stickstoffentzug von Lolium multiflorum

Effect of straw and nitrapyrin application on the nitrogen availability in the soil and the yield and nitrogen uptake of Lolium multiflorum. In pot experiments the effect of straw and nitrapyrin application on the turn-over of fertilizer NH and on the nitrogen availability in the soil was investigated. The investigation comprised two sections: an incubation experiment in which straw and nitrapyrin together with NH-N were incorporated into a brown podsolic soil and a subsequent pot experiment with ryegrass. Nitrapyrin inhibited the nitrification and reduced the nitrogen loss of the soil. Compared with the treatments without nitrapyrin application, nitrapyrin resulted in a lower dry matter yield and in a lower nitrogen uptake of the ryegrass. Straw application reduced the nitrate content in the soil significantly. This effect was particulary evident in the treatments which did not receive nitrapyrin. Accordingly, nitrogen uptake and yield of ryegrass were significantly lower in the ‘straw treatments’ as compared with the treatments without straw. It is suggested that the impared nitrogen availability in the ‘straw treatments’ was mainly due to nitrogen losses caused by denitrification.     

Einfluß von Herbiziden auf die N2-Fixierung und Atmungsaktivität von Mikroorganismen in Ackerböden

Influence of herbicides on nitrogen fixation and respiration activity of microorganisms in arable soils The influence of pesticides on nitrogen fixation (acetylene reduction test) as well on respiration activity was determined in model experiments. The following soils were used: Chernozem from loess (Boroll), Luvisol from loess (Boralfs), Rendsina (Lithic Rendoll), Pelosol (Fine textured Cambisol) and Humic Podzol (Humod). The tested soils differed considerably in both parameters. The rendsina showed remarkably low fixation rates whereas the podsol reduced acetylene only at higher water contents. The soil herbicides chlortoluron, terbutryne, metabenzthiazuron and chloridazon did not affect the course and the magnitude of the tested parameters even not at higher doses. Only the leaf herbicide dinosebacetate revealed a distinct inhibition of nitrogenase activity in the podsol and in the luvisol from loess. The fungicide carbendazime caused a strong stimulation of the nitrogenase activity in all soils. The respiration activity could not been influenced significantly.     

Der Einfluß von Niederschlag und Höhenlage auf den Humusgehalt ostafrikanischer Böden

The influence of precipitation and altitude on the humus content of East African soils Positive correlations were found between the log of the carbon and nitrogen content of the 0–15 cm soil layer, altitude and average annual precipitation of 20 grassland soils, 13 forest soils and 21 cultivated soils at altitudes of 10–2840 m and a precipitation of 380–2410 mm in Kenya, Tanzania and Uganda. For each of the soil groups equations with the two variables altitude and precipitation were derived, which accounted for 76–93 per cent of the variation of the carbon (0,42–5,62%) and nitrogen (0,04–0,71%) content. There was no correlation between altitude, precipitation and the C/N ratio of the soils.     

Einfluß von Natriumchlorid und Mycostatin auf den Mineralstoffgehalt im Blattgewebe und die Feinstruktur der Chloroplasten

Effect of Sodium Chloride and Mycostatin on the Mineral Content of Leaf Segments and on the Fine Structure of Chloroplasts Leaf segments of bean, barley and sugar beet were treated for several hours with 25 meq NaC1 or with the antibiotica mycostatin. The effect of these treatments on the content of potassium, sodium, calcium, magnesium and chloride in the leaf segments and on the fine structure of chloroplasts was studied. In bean sodium chloride treatment induced strong efflux of potassium and swelling of the chloroplasts. Sodium sulfate or mycostatin had the same effect. Despite of the strong efflux of potassium the content of calcium and magnesium in the segments was practically unaffected. Addition of 1 meq calcium to the external solution prevented the effect of sodium chloride on efflux of potassium as well as on the fine structure. In barley sodium chloride or mycostatin also induced efflux of potassium and swelling of the chloroplasts. These effects, however, were less pronounced than in bean. Again the content of calcium and magnesium in the segments was practically unaffected, and the addition of 1 meq calcium compensated the effect of sodium chloride. In sugar beet both mycostatin and sodium chloride did not induce efflux of potassium, despite of a strong influx of sodium in the sodium chloride treatment. In both treatments no change in the fine structure of the chloroplasts was observed. It was proved by isolation of chloroplasts that the typical sodium chloride induced differences in efflux of potassium from the leaf segments is also reflected in efflux of potassium from the chloroplasts. The results indicate the causative connection between efflux of potassium and change in the fine structure of the chloroplasts. Differences between the three plant species with respect to efflux of potassium induced by sodium chloride or mycostatin are reflections of different membrane properties. The presence of calcium in the external solution is much more important for the membrane stability of bean than it is for sugar beet e. g. The results obtained with leaf segments are a good reflection of the different tolerance of these three plant species to high sodium chloride concentrations under field conditions.     

Einfluß von Sorte und Phosphordüngung auf den Phosphorgehalt und die Aktivität der sauren Phosphatasen von Weizen und Gerste. — Ein Beitrag zur Diagnose der P-Versorgung von Pflanzen —

Influence of cultivar and phosphorus application on P concentration and acid phosphatase activity in wheat and barley. — A contribution to the diagnosis of P supply of plants — Acid phosphatase activity compared to total P concentration was studied as a diagnostic criterion of the phosphorus nutritional status of wheat and barley. In a field experiment with wheat cv ‘Sperber’ the influence of P level on P_ase activity and P concentration was monitored at four developmental stages. Significant correlations with grain yield were found for P_ase activity at all four stages whereas P concentration was significantly correlated with grain yield in the early stage (DC 26–27) only. Genetic variability and influence of P supply on P_ase activity and P concentration was studied at low and at high P supply with 9 wheat and 23 barley cultivars grown for 4 and 5 weeks in pot experiments. The variability of P_ase activity caused by cultivars was higher than that caused by P supply. It is, therefore, concluded that the acid phosphatase activity is not suitable as a generally applicable tool for diagnosing P supply. In comparison, total P concentration of the plants was influenced to a higher degree by P supply than by cultivars. Total P is, therefore, more suitable as a criterion for diagnosing P supply of plants than P_ase activity. The samples, though, have to be collected in stages before DC 27.     

Einfluß verschiedener Substanzen auf den Eindringwiderstand von Bodenpasten

Effect of different substances on the resistance of penetration of soil pastes A preliminary study was carried out to test for to what extent the molecular forces of a soil may be influenced. Soil pastes treated with Alginure', Ca(OH)₂, NaCl, KCl, organic matter, or ferrihydrite, were prepared from topsoil samples of two eroded Typic Hapludalfs derived from loess (A_p within the A_l and B_t horizon, resp.). Following airdrying and breaking the pastes, the penetration resistance of 8–12 mm aggregates was measured at 4 different applied water suctions. These resistances to penetration are correlated with the applied water suction by lg(resistance) = ?a+b*(suction) and with the aggregate water content by lg(resistance) = a-b*lg(water content). The resistances to penetration of the B_t-pastes are constantly higher than those of the A_l-pastes. If any change due to treatment occurred, adding a substance decreased the resistance to penetration of the B_t-pastes whereas those of the A_l-pastes were increased. As differences due to parent material and treatments occured at >10kPa and >30kPa applied water suction, resp., it is assumed that they essentially effect the surface tension of the soil water, which on its part influences the force of cohesion of the water menisci. This force of cohesion affects the degree of aggregation and thereby among others the resistance to penetration of a soil.