Zur hydrologischen Bedeutung der organischen Auflage im Wald: Untersuchungsmethoden und erste Ergebnisse

About the hydrological role of organic layers in forest: methods and first results The forest floor (total organic matter above the surface of the mineral soil) is an important interception storage for throughfall. Therefore, it must be considered in detailed water balances of forest. The objective in this paper is to present a method for measuring the forest floor percolation. It was developed within the framework of the interdisciplinary project Ecosystem research in the Bornhöved lake region. A technique for permanent registration of mineral soil input and a vacuum control system for mini lysimeters and suction plates are described. The registration system has a resolution about 0,1 mm. Some figures illustrate the instrumentation, respectively measured row data and some results. Finally, the used materials, their properties and sources of supply are presented.     

Ein Beitrag zur Kenntnis der Formenmannigfaltigkeit der Kulturtomaten (L. esculentum Mill.) Mittelamerikas

Zusammenfassung Es wird die Zusammensetzung einer Sammlung von Land- bzw. Primitivsorten der Kulturtomaten aus Mittelamerika beschrieben. Diese wurden von F. Schwanitz im Jahre 1958 in den Staaten El Salvador, Guatemala, Honduras und Costa Rica gesammelt. Die Früchte stammen hauptsächlich von den Märkten der Ortschaften.Es werden die Merkmale des Sprosses und der Fiederblätter sowie der Blüten und Früchte beschrieben, die die Formenmannigfaltigkeit dieser Tomatenkollektion charakterisieren. Die in dem Material vorkommenden Fruchtformen lassen sich in vierzehn Gruppen zusammenfassen. Darunter fallen besonders auf: die extrem langen, bleistiftförmigen Früchte, die länglich-breiten, beutelförmigen Früchte sowie die Früchte mit isoliert stehenden Carpellen. Sehr zahlreich sind bei fast allen Fruchtformen die violettroten Früchte mit durchsichtiger Fruchthaut.Während der Bearbeitung konnte eine starke Heterozygotie des Materials beobachtet werden, aus der man auf eine weit verbreitete Fremdbefruchtung bei den kultivierten Tomaten dieser Gebiete schließen kann.Zum Schluß werden die Eigentümlichkeiten der Formenmannigfaltigkeit der Tomaten dieser Länder erörtert. Daraus ergibt sich, daß das Zentrum der Formenmannigfaltigkeit der kultivierten Tomaten von dem Süden Mexikos (Gebiet von Veracruz und Puebla) bis nach El Salvador und Honduras reicht.

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Summary The varietal diversity of a collection of tomatoes (landraces or primitive strains) from Central-America is described. The tomatoes were collected in 1958 by F. Schwanitz in El Salvador, Guatemala, Honduras, and Costa Rica, mainly in native markets (fig. 1, table 1).The progenies of the collected fruits were separately cultiveted at Gatersleben from 1960 to 1964. Characters of shoots, leaves, flowers, and fruits are described as far as necessary for characterizing this collection (figs. 2-19). The fruit-forms are grouped into 14 types (figs. 20-41). Among these are extrem long-fruited, so-called lead pencil-shaped (fig. 24), wide oblong-fruited, so-called baggy-shaped (fig. 30) fruits and other ones with so-called isolated carpels (figs. 38 and 40). Nearly all the types include tomatoes with colourless skin, which imparts to the ripe fruit a pinkish cast.There was observed a high degree of heterozygosity which can be attributed to a considerable frequency of natural cross-pollination in these countries.The results of this inquiry are discussed with regard to the peculiarity of this great range of tomato types in Guatemala, Honduras, and El Salvador. Hence it follows that the Southern Mexico center of varietal diversity of cultivated tomatoes, the Veracruz — Puebla area in particular (cf. Jenkins 1948), extends to El Salvador and Honduras.

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Ein Beitrag zur Kenntnis der Gaterslebener Mutanten der SojabohneGlycine max (L.) Merr.

Zusammenfassung In einer ersten Mitteilung werden aus dem Sortiment röntgeninduzierter Mutanten der Sojabohnensorte Heimkraft I 19 Mutanten nach ihren Hauptmerkmalen benannt und in das morphologische System der Sojabohne,Glycine max (L.) Merr. eingeordnet. Die Mutanten haben die taxonomische Rangstufe einer Linie (der gleiche Rang wie Sorte bzw. Cultivar). Sie können 8 verschiedenen Varietäten der Art zugeordnet werden.

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Summary Within a first report 19 X-ray induced mutants of the soybean variety Heimkraft I are named according to her main characters and integrated into he morphological system of the soybean,Glycine max (L.) Merr. The mutant lines are of the same level as cultivar (variety). They are placed in 8 different varieties (varietates).

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a I ¶rt; 19 , . Glycine max (L.) Merr. . .

     

Kurzmitteilung Ein methodischer Beitrag zur Porengrößen-Messung bei Böden

A methodic contribution for the measuring of volume of pores in soils An apparatus for determination of the soil pores in the pF-range 0–2,5, partially produced in home-work, is described. Thereby are used ceramic plates 50 × 35 cm with a thickness of 5–8 mm. The ceramic plates are sticked on 63 × 50 cm gum plates with Teroson-Cement-BE and packed in correspondingly great wooden boxes. The soil samples are dehydrated in an over-pressure chamber.     

Ergebnisse von Simulationsrechnungen mit einem Bodenstickstoffmodell zur Düngung und zum Zwischenfruchtbau in Trinkwasserschutzgebieten

Results of computer simulations on fertilization and catch cropping problems in water protection areas by means of a soil nitrogen model A simple model of the nitrogen turnover in soil is presented. The model was validated by field experiment time series. The simulation results showed that dividing of the mineral nitrogen fertilization during spring for root crops or maize as well as shortening the first spring nitrogen fertilization for winter cereals diminished the leaching of nitrate only in extremely wet springs on sandy soils. The great importance of winter catch cropping in a cereal-root crop or a cereal-maize rotation on all soils and the necessity to avoid liquid manuring during late summer and early autumn, especially on sandy soils without catch cropping, are demonstrated. The results underline the predominant influence of the weather conditions on nitrate leaching.     

Ergebnisse zur Niederschlags-Interzeption in landwirtschaftlichen Pflanzenbeständen

Results concerning rainfall interception in agricultural plant stocks The paper summarizes analysis of the losses of precipitation due to interception for the agricultural crops silomaize, oat and sugarbeet. These analysis have been carried out from 1979 to 1981 and from 1985 to 1986 in the maritime region of the German Baltic coast (Mecklenburg). An average of 29% for silomaize, of 47% for sugarbeets, and of 48% for oats of the total precipitation has been lost through interception. The losses are mainly determined by the amount, intensity and distribution of rainfalls and by the rates of change of leaf surface throughout the vegetation period. These factors are part of a multiple quadratic function to compute the interception, which has sometimes been neglected when studying the water balance of agricultural crops.     

Ein Gerät zur Herstellung spektrochemischer und anderer homogen zu mischender Proben

An apparatus for homogeneous micro-grinding of spectrochemical and other samples 1. For spectrochemical analysis of solid substances, mixtures which must fulfil definite criteria are required. The degree of the needed purity, completeness and homogeneity is described. 2. To obtain homogeneous material, the substance must be finely ground within a short time. The grinding problem was solved by developing an apparatus which includes a modefied mortar and pestle. Special points of construction which guarantee the specifications of grinding are given for both operation and efficiency. 3. The construction of the apparatus which is now manufactured is elucidated. The method of the applied test of qualifications is outlined.     

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.     

N-Umsatz von verschiedenem Pflanzenmaterial im Boden in Gefäß- und Feldversuchen

Turnover of nitrogen of different plant material in the soil in pot and field trials In pot and field trials, effects of various plant materials like green rape, sugar beet leaves, potato foliage, straw of wheat, maize, or field beans, on the turnover of N in the soil (mineralization, N_min-concentrations, NO₃-leaching) and on yield and N uptake by some crops was tested in relation to mineral N fertilizer application. In both experiments, widely corresponding results were obtained: Irrespective of the N contents of the plant material, biological immobilization of N always was combined with beginning mineralization (pot trial: decrease of NO₃ leaching in late fall). Green rape (C/N = 12/1) showed already after 4 weeks in the field trial a marked net mineralization (N_min) of 20–30% of the added nitrogen which was quantitatively reflected in higher removals of N. Beet leaves (C/N = 20/1) were decomposed at a much slower rate in combination with an increase in N removals of subsequent crops by 6-20 % depending on the rate of mineral fertilizer application. All types of straw (CM = 57-8611) and potato foliage (CM = 73/1) caused a marked biological immobilization of N which resulted in reduced N removals depending on turnover rate (potato foliage: fast, wheat straw: slow) and N contents of the organic material. Different plant residues (straw, leaves) were applicated on a harvested field with cereal to test comparatively one part of the total value of different preceding crops; at onset of vegetation the N_min-contents in soil, depending on the climatic conditions during the non-growing season for mineralization, were analyzed.     

Räumliche Spannungsmessungen mit dem Stress State Transducer (SST) in ungesättigten aggregierten Böden - theoretische Betrachtungen und erste Ergebnisse

Stress measurements in undisturbed unsaturated soils with a Stress State Transducer (SST) - theory and first results A method to quantify the spatial stress distribution will be introduced and first results will be discussed. This method allows the detailed analysis of principal and shear stresses as well as the determination of the direction angle of principal stresses and the octahedral shear stress angle. The described Stress State Transducer (SST) is composed of six single strain gage sensors that enable the accurate and reproducable recording of stresses in six directions in a wide load range. Their data form the base for calculation of spatial stress distribution. Some first results show that in a luvisol derived from loess wheeling at a wheel load of 4.0 Mg induces high shear stresses in a depth of 30 cm. This probably causes plastic soil deformation.