Einfluß von Kupfer- und Stickstoffmangel auf die Aktivität der Phenoloxidase und den Gehalt an Phenolen in den Blättern der Sonnenblume (Helianthus annuus)

Effect of copper and nitrogen deficiency on phenol oxidase activity and content of phenols in leaves of sunflower (Helianthus annuus) In sunflower leaves of different insertion height the activity of phenol oxidase during the course of the whole vegetation period was determined. In leaves of normal plants this activity reached its maximum during the period of most intensiv growth and decreased continuously with increasing age. The highest activity was found in cotyledons. In normal leaves this maximum decreased with increasing insertion height. Copper deficiency led in cotyledons to a small, in leaves to a severe inhibition of the phenol oxidase activity. Here the decrease of copper content always led to an unproportional decrease of the enzyme activity. After the middle of July, no phenol oxidase activity in leaves of copper deficient plants could be determined. Nitrogen deficiency decreased the yield considerably, while it was lowering the phenol oxidase activity only slightly. Orthodihydroxyphenols, as substrates of phenol oxidase, showed a negative correlation to the enzym activity: The stronger the suppression of the phenol oxidase activity, the higher was the rise of the orthodiphenol content in full expanded leaves. With unsufficient copper supply the plants showed only week deficiency symptoms, although the phenol oxidase activity was completly inhibited. Therefore it is presumed that in sunflower leaves the role of phenol oxidase can partly be taken over by other enzymes.     

Einfluß der Stickstoffernährung auf den Gehalt an Chlorophyll und Galaktolipiden alter und junger Rapsblätter (Brassica napus L.)

Effects of nitrogen nutrition on the contents of chlorophyll and galactolipids in young and older leaves of oil-seed rape (Brassica napus L.) The effect of nitrogen nutrition upon chemical characteristics of chloroplasts from young and older leaves of oil-seed rape (Brassica napus L.) were investigated. Nitrogen influenced the chlorophyll content especially of older leaves. As compared to the optimum supply, the values of young leaves were only reduced at the extreme deficiency and the excessive supply. In contrast to the content of chlorophyll the amounts of monogalactosyl diglyceride of both young and older leaves depended strongly on N-supply. Generally, the amounts of digalactosyl diglyceride were not related to leaf-age and N-supply. With the exception of extreme deficiency the contents of linolenic acid in galactolipids were influenced by nitrogen mainly in older leaves. (Brassica napus L., N-supply, Leaf-age, Chlorophyll, Galactolipids)     

Einfluß von Stickstoffernährung und Wuchsstoffapplikation auf die Knolleninduktion bei Kartoffelpflanzen

Influence of nitrogen nutrition and application of growth regulators on tuber initiation in potato plants In water culture the effect of continuous and discontinuous N-nutrition on tuber initiation was investigated. Additional applications of growth regulators on growing stolon tips were carried out. Continuous supply of nitrate or ammonium inhibited completely the tuber initiation in S. tuberosum varieties ?Ostara”? and ?Clivia”?, The inhibition was compensated by application of CCC and ABA on the stolon tip. In contrast to this stolon application of kinetin and root application of CCC were ineffective. Temporarily damaging of the root system led to tuber initiation even when nitrogen was supplied continuously. In S. andigena grown under short day continuous N supply only delayed the tuber initiation but could not prevent it. Discontinuous N supply promotes tuber initiation in S. tuberosum. A sudden increase in N supply caused ?re-growth”? of the tuber, i.e. a stolon was formed on the tuber apex. GA₃ application on the growing tuber had the same effect. The effect of N nutrition on tuber initiation can be explained via changing the balance of endogenous growth regulators in general and the physiological aging of the leaves in particular. Discontinuous N supply seems to reduce cytokinin production in roots and therefore accelerates the aging of the leaves. This in turn favours the formation of inhibitors and/or presumably reduces the GA production in the shoot, which will change the balance of the growth regulators in the stolon tip in favour to tuber initiation.     

Einfluß der Cl-Ernährung auf Ertrag und Nitratgehalt von Spinat und Kopfsalat

Effect of Cl-supply on yield and nitrate content of spinach and lettuce The N-supply for maximum yield could be reduced for spring spinach from 250 to 200 kg N/ha, for autumn spinach from 200 to 150 kg N/ha without yield depressions by optimized Cl-supply. The optimal Cl-supply consisting of Cl-content in 0–60 cm soil depth and Cl-fertilization was about 350 kg Cl/ha. However, Cl-supply in top soil should not exceed 300 kg Cl/ha in order to avoid emergence decreases. Different amounts of Cl-fertilizer were necessary because soils of experimental sites contained chloride in the range of 66 to 435 kg Cl/ha. The nitrate content was reduced up to 50% by Cl-fertilization. This was caused by reducing the N-supply by 50 kg N/ha and to an increased nitrate reduction. The heighest head weight of lettuce could be achieved with N-supply of 90 kg N/ha and additional Cl-fertilization. Reducing the N-supply from 120 to 90 kg N/ha and improvement of Cl-nutrition decreased nitrate content considerably. Cl-supply should not exceed 150 kg Cl/ha in 0–30 cm, because lettuce reacts sensitive to saline conditions.     

Einfluß der Lichtintensität bei variierter Kaliumernährung auf CO2-Assimilation und Ertragsbildung bei Sommerweizen

Effect of light intensity at varied potassium supply on CO₂ assimilation and yield formation of spring wheat .

• 1 The effect of a varied K⁺ supply on CO₂ assimilation rates and yield formation has been studied at two different light intensities with wheat (Triticum aestivum L.) grown in solution culture. Light intensity was reduced in one treatment by shading the plants with a cloth, which caused a reduction of about 50 % of the light intensity. This shading was applied from the heading stage until grain maturation.
• 2 Reduced light intensity resulted in remarkably decreased rates of dry matter increments in both K treatments. In the beginning this growth depression, however, was small in the treatment with the higher K supply. At the stage of transition from the vegetative to the reproductive stage the better K⁺ nutrition obviously could compensate the lacking light to some degree. This favourable K⁺ effect, however, decreased with the advance of the reproductive phase. Thus at maturation in both K treatments equal quantities of dry matter were harvested. In the treatments with full light the higher K supply resulted in a yield increase at maturation.
• 3 The CO₂ assimilation rates measured at flowering, milk stage and dough stage indicated that rather the K supply than the light intensities influenced the CO₂ assimilation. The treatments with the higher K supply showed almost twice as high assimilation rates compared with the treatments with the lower K supply.
• 4 The reduced light intensity caused a substantial depression in grain yield in both K treatments. The poor grain yield was mainly due to a reduced thousand grain weight and to a less extent to a reduction in the number of ears.
• 5 As the better K supply resulted in increased CO₂ assimilation rates without having an influence on the grain filling of the plants exposed to a lower light intensity, it is concluded that at low light intensities the grain filling is not limited by the supply of grains with photosynthates but probably is affected by other processes.

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Einfluß des Calcium-Angebotes auf Wachstumsrate und Calcium-Gehalt von Kartoffelknollen

Effect of calcium supply on growth rate and calcium content of potato tubers. . Using potato plants in water culture with a constant calcium supply to the roots, a study was made of the influence of additional supply of calcium to the tuber surface on growth rate and calcium content of the tubers. Under conditions of high relative humidity around the tubers the calcium nutrition of the tubers was exclusively dependent on the calcium supplied to the tuber surface (?exogenous calcium”?). With a high level of exogenous Ca the growth rate of the tubers was high and the rate of uptake of Ca was proportional to the tuber growth. With a low level of exogenous Ca the growth rate declined to a lower but constant value. In absence of exogenous supply of Ca the growth rate of the tubers declined gradually until growth ceased. Cessation of tuber growth occurred when the Ca content decreased below 0,36 mg Ca per g dry matter for smaller tubers and below 0,14 mg Ca per g dry matter for larger tubers. Severe Ca deficiency in potato tubers causes necrosis at the tuber apex.     

Untersuchungen über den Einfluß von Gibberellinsäurespritzungen auf den Ertrag,die Anatomie der Wurzel und die Karotinverteilung bei Karotten

Investigations on the Influence of Gibberellic Acid Treatments on Yield, Root Anatomy and Carotene Distribution of Carrot Plants . Application of GA₃ onto the shoots of carrot plants increases shoot growth whereas root growth was reduced. Furthermore, due to the GA₃-application carotene content (Table 2) in the shoots was increased and decreased in the roots. Anatomical investigations of the roots revealed that apparently the reduction of root growth after GA₃-application was due to a decrease of phloem oriented cambial activity (Table 3).     

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 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.     

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.     

Der Einfluß von P-Ernährung und pH auf die Phosphataseaktivität von Zuckerrübenwurzeln

The influence of phosphorus nutrition and pH on phosphatase activity of sugar beet roots For the determination of acid phosphatase activity (P_ase) of sugar beet roots (cultivar: Reka), plants were cultivated in nutrient solution with 1 or 100 μM P in a growth chamber for 12, 18, 24, 30, 36 and 42 days. The phosphatase activity of intact roots was measured in buffer solutions with pH 4 to 7.2 and 14 mM p-Nitrophenylphosphate (NPP) after 10 min of incubation at 20°C. The influence of P nutrition on P_ase activity was significant at all intervals. At P deficiency the activity was increased by a factor of 4 to 20. During the experimental period the pH optimum was 6. At pH 5 and 7.2 the P_ase activity reached only 63 and 64% respectively of the optimum value. At P deficiency (1 μmol P L^—1) the absolute rate of NPP-hydrolysis at pH 6 was 144 nmol min¹ m¹ root length (day 12 to 36). The plants which received optimum P supply showed only 10% of this value. Sugar beet roots with P deficiency have a high potential of P_ase activity from the acid to the neutral pH-range. Therefore, under this condition they may effectively use dissolved organic phosphorus compounds.     

Der Einfluß der Kalium-Ernährung auf den Gehalt und das Spektrum löslicher Aminoverbindungen in Rotklee (Trifolium pratense L.)

Effect of potassium nutrition on the content and the spectrum of soluble amino compounds in Red Clover 1. A better K nutrition of Red Clover (Trifolium pratense) resulted in higher contents of soluble amino acids of the upper plant parts. The plants of the treatment with the highest K application showed nearly double as high contents of glutamic acid, aspartic acid, alanine and γ-aminobutyric acid than the plants of the K₀ treatment. The content of asparagine was not as much affected by the K nutrition and the content of glutamine was even lowered. 2. Red Clover responded on the K treatment with its content of soluble amino compounds quite different than non leguminous plant species which show decreasing contents of soluble amino acids with an increasing K nutrition. Therefore it is concluded, that the K nutrition of legumes affects the N₂-fixation of Rhizobium leguminosarum. 3. The higher contents of soluble amino compounds did not influence the protein content of the upper plant parts. But with the better K supply the yields were increased considerably and therefore also higher yields of proteins were harvested. Very low K supply resulted in a high protein content, due to an inhibition of plant growth.     

Einfluß einer mineralischen und symbiontischen Stickstoffernährung auf Protonenabgabe der Wurzeln,Phosphat-Aufnahme und Wurzelentwicklung von Rotklee

Influence of mineral and symbiotic nitrogen nutrition on proton release of roots, phosphorusuptake and root development of red clover Red clover was cultivated in pots containing a loamy sand soil of low buffer capacity. Nitrogen supply was either NH₄NO₃ and Ca(NO₃)₂ in the mineral treatment or Rhizobium fixed N₂ in the symbiotic treatment. During six cuts the plants decreased the pH of the soil from 7.6 to 6.0 in the mineral treatment and to 5.2 in the symbiotic treatment. Both treatments yielded the same amount of shoot dry matter per pot. The N₂-fixing red clover produced more root fresh weight associated with larger root length, root surface, and root density per pot compared with plants grown with mineral nitrogen. Due to stronger soil acidification and better root growth N₂-fixing red clover was able to exploit the rock phosphate component from a partially acidulated P-fertilizer to a higher degree than NH₄NO₃ or Ca(NO₃)₂ fed plants. The proton release of symbiotically grown plants could be accounted for by mineral cation excess (difference of cation and anion uptake) in shoots and roots by only 68%. It is therefore assumed that the excess of H⁺ released was accompanied by a release of anions.     

Einfluß der Probenvorbereitung auf die Adsorption von Cd und Cu in sauren Waldböden

Influence of Soil Sample Preparation on Cd and Cu Adsorption in Acid Forest Soils The influence of soil sample preparation on Cd and Cu adsorption was investigated using six acid forest soil samples and comparing adsorption isotherms for fresh and air-dried samples. While no influence of sample preparation on Cd adsorption capacity was found, air-drying resulted in a significant decrease in Cu adsorption density in all six soil samples under investigation at ecotoxicologically relevant concentrations in the soil solution.     

Der Einfluß der Fauna auf die Stoffverlagerung sowie die Homogenität und die Durchlässigkeit von Böden

The influence of the fauna on displacement and on homogeneity and permeability of soils The influence of the most important soil animals (mammals, ants, termites, woodlice and earthworms) on displacement and on homogeneity and permeability of soils is discussed in reference to both older and more recent literature. Nearly all soil animals cause displacement of organic and mineral soil particles. The quantity, intensity and direction of this activity depends upon the morphological characters of the species involved. The homogeneity of soils is positively influenced only by the earthworms (and related forms) whereas the activity of the other soil fauna mostly has a contrary effect as far as shorter periods are concerned. The permeability of soils increases in different dimensions due to the activity of all species discussed. Permanent vegetation and non-tilling for the most part favour the activity of the soil fauna. Recent field experiments dealing with minimum or zero tillage have made this fact fairly evident.