Nitrous oxide emissions after incorporation of winter oilseed rape (Brassica napus L.) residues under two different tillage treatments

The aim of this study was to investigate the effect of crop residues from winter oilseed rape on N₂O emissions from a loamy soil and to determine the effect of different tillage practices on N₂O fluxes. We therefore conducted a field experiment in which crop residues of winter oilseed rape (Brassica napus L., OSR) were replaced with ¹⁵N labelled OSR residues. Nitrous oxide (N₂O) emissions and ¹⁵N abundance in the N₂O were determined for a period of 11 months after harvest of OSR and in the succeeding crop winter wheat (Triticum aestivum L.) cultivated on a Haplic Luvisol in South Germany. Measurements were carried out with the closed chamber method in a treatment with conventional tillage (CT) and in a treatment with reduced soil tillage (RT). In both tillage treatments we also determined N₂O fluxes in control plots where we completely removed the crop residues. High N₂O fluxes occurred in a short period just after OSR residue replacement in fall and after N‐fertilization to winter wheat in the following spring. Although N₂O emissions differed for distinct treatments and sub‐periods, cumulative N₂O emissions over the whole investigation period (299 days) ranged between 1.7 kg and 2.4 kg N₂O‐N ha^?1 with no significant treatment effects. More than half of the cumulative emissions occurred during the first eight weeks after OSR replacement, highlighting the importance of this post‐harvest period for annual N₂O budgets of OSR. The contribution of residue N to the N₂O emission was low and explained by the high C/N‐ratio fostering immobilization of mineral N. In total only 0.03% of the N₂O‐N emitted in the conventional tillage treatment and 0.06% in the reduced tillage treatment stemmed directly from the crop residues. The ¹⁵N recovery in the treatments with crop residues was 62.8% (CT) and 75.1% (RT) with more than 97% of the recovered ¹⁵N in the top soil. Despite our measurements did not cover an entire year, the low contribution of the OSR residues to the direct N₂O emissions shows, that the current IPCC tier 1 approach, which assumes an EF of 1%, strongly overestimated direct emissions from OSR crop residues. Furthermore, we could not observe any relationship between tillage and crop residues on N₂O emission, only during the winter period were N₂O emissions from reduced tillage significantly higher compared to conventional tillage. Annual N₂O emission from RT and CT did not differ.     

Möglichkeiten,Grenzen und Aufgaben der biologischen Schädlingsbekämpfung in Deutschland

Ohne ZusammenfassungNach einem vor dem Pflanzenschu-Ausschuß der DLG am 5. 11. 53 in Darmstadt gehaltenen Vortrag.     

Die gegenwärtige Situation der biologischen Schädlingsbekämpfung in Deutschland

Ohne Zusammenfassung     

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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am ¶rt;au , . 1958 . , , -. , , , . I. 1960 1964 . ( , . 18–41) (. 2–17). 14 (. 20–41). : «» (. 24), - «» (. 30) « » (. 38 40). - . , . . , , ( — . 1948) .

     

Control of soil-borne pathogens with living bacteria and fungi: Status and outlook

This review addresses some of the current problems with soil-borne pathogens and their economic importance in comparison to the total plant protection market- Possible opportunities for biological control solutions in view of the various constraints of western agricultural production are discussed. More specifically, we address the scientific, economic and conceptual hurdles which have slowed down the development of biocontrol agents. In addition, examples of biological control of soil-borne pathogens which have already reached the market or are likely to be exploited commercially within the next few years are presented. Finally, we speculate on certain developments which might become important for the further commercial development of biological control products.     

Detection of antibodies against the virus causing viral gastroenteritis in swine using the modified autoradiography test

A modified method for autoradiographic determination of antibodies to the virus of transmissible gastroenteritis of swine was developed. It is based on the actual reaction between antigen bound in cells of the infected cell cultures and antibodies in tested sera, which is visualized, by help of rabbit antibodies marked 125J (125J RaSw IgG antibody) to porcine IgG, on a sensitive radiograph and evaluated on the basis of darkening at the point of positive immunological reaction. Specificity of the test and mutual comparability and reproducibility of the results were confirmed by examining the known positive and negative sera and by comparison with the results of the virus-neutralisation test. Out of the 36 examined porcine blood sera the antibodies were proved autoradiographically only in the samples positive also by virus-neutralisation. In experimentally infected pigs, the same dynamics of antibody production was recorded by the two tests. They were, however, demonstrated autoradiographically already by the two tests. They were, however, demonstrated autoradiographically already the eighth day after infection, while by virus neutralisation test as late as 14th day. Their level increased gradually until 35th day after infection.     

Diagnosis of bovine coronaviruses using mouse erythrocyte suspensions stabilized with formalin

Bovine coronavirus isolated from calf faeces diseased with gastroenteritis and passaged to colostrum-free calves agglutinated mouse and rat erythrocytes. The agglutination reaction depended on temperature and took place only at a temperature of 4 degrees C. At a temperature of 37 degrees C the agglutinate broke down within 15 minutes. The coronavirus could be detected by the haemagglutination test in the contents of the small and large intestines and in the faeces of experimentally and naturally infected calves. The agglutination capacity of mouse erythrocytes was not affected by careful fixation of these erythrocytes with formalin and subsequent lyophilization and remained unchanged for as long as 52 weeks of storage at a temperature of 4 degrees C. It was demonstrated by a comparative examination of 182 samples of the faeces of calves suffering from diarrhoea that haemagglutination test was as sensitive as electron microscopy.