The influence of calcium on growth of selected vegetable species in the presence of ammonium nitrogen

Growth of cabbage (Brasslca oleracea L.), cantaloupe (Cucumis melo L.), squash (Cucurbita pepo L.), chile pepper (Capsicum annuum L.), tomato (Lycopersicon esculentum Mill)., radish (Raphanus sativus L.), and Swiss chard (Beta vulgaris L.) was enhanced when supplied with additional Ca in the presence of NH₄‐N over those with normal Ca. Ammonium uptake as measured by residual NH₄ in soil leachate was lowered indicating possible increased uptake in the presence of additional Ca.     

The derivation of grassland vegetation types on the basis of site and land use characteristics

This study derives grassland communities from site, climate and land use characteristics, allowing yield estimation within the framework of model scenarios. Based on the dominant species, about 450 relevés, primarily of extensively used grassland from four regions of the North-East German lowlands, were classified into vegetation types using a cluster analysis. These types were then reclassified to known phytosociological communities. The relationship between the vegetational composition and the abiotic explanatory variables were verified by a discriminant analysis. The water supply level proved to be the most important factor influencing grassland vegetation. The impact of historical land use (especially the persistence of formerly sown species) reduced prognostic quality.     

Möglichkeiten zur komplexen steigerung der abiotischen stresstoleranz bei winterraps∗

Auf Basis von Hydrokultur‐ und Feldversuchen wurden Ursachen für die im Winterraps vorhandenen Variabilitäten der N‐Effizienz ‐ getrennt nach ihren Komponenten N‐Aneignung und N‐Verwertung ‐ ermittelt. Als Versuchsmaterial dienten die Verbundhybride “Synergy”;, die Normalrapssorte “Sollux”; und zwei DH‐Linien mit unter‐schiedlcher N‐Effizienz. Es zeigte sich, daß die N‐Aneignungseffizienz sehr stark durch die Wurzelsaugkraft und die N‐Verwertungseffizienz durch das N‐Translokationsvermögen beeninflußt wird. Beide Komponenten fördern die Gesamt‐N‐Effizienz und zusätzlich die Trockentoleranz. Die gewonnenen Erkenntnisse sind in einem Selektionsprogramm zur Steigerung der abiotischen Streßtoleranz zusammengefaßt worden.     

Auswirkungen variierter kaliumdüngung auf niedermoorgrünland

Die Veröffentlichung befaßt sich mit der K‐Dynamik bei der Grünlandbewirtschaftung auf Niedermoor und den daraus resultierenden Kaliumbilanzen für die Modellierung. Sie beinhaltet Angaben zur Steuerung der K‐Düngung bei Mäh‐ und Weidenutzung unter Berücksichtigung der Nährstoffflüsse. In dem Beitrag werden vor allem die Besonderheiten der Niedermoorstandorte dargelegt. Bei extensiver Grünlandbewirtschaftung auf Niedermoor können die K‐Düngergaben zwar reduziert werden, ein völliger Verzicht ist aber nicht ratsam, da es schon nach zwei Jahren zur Unterversorgung kommt. K‐Mangel bewirkt neben einer reduzierten Biomasseproduktion eine reduzierte Stickstoffausnutzung bei hoher N‐Nachlieferung des Standortes und eine Verschlechterung der Pflanzenbestandszusammensetzung durch den Rückgang wertvoller Arten.     

Some biochemical parameters for qualification of bull semen

Summary

Since the macroscopical and microscopical examination of bull semen does not in all cases appear to give conclusive indications concerning the fertilizing capacity, an investigation of some biochemical parameters was undertaken. It was shown that the following biochemical examination could furnish some more information about the quality of the semen: 1. Determination of the phenylalanine‐ α‐ketoglutarate transaminase activity both in the seminal plasma and in the whole semen. A high transaminase activity in the plasma points to leakage out of the spermatozoa, thus indicating an affection of the spermatozoa. In that case larger amounts of basic amino acids and of leucine were often found in the seminal plasma than would normally be observed.

2. Gas chromatographic examination of the steroids occurring both in the seminal plasma and in the spermatozoa. In a number of infertile bulls small peaks of progesterone were found together with those of other, unidentified compounds.

3. Investigation of the carbohydrate metabolism in the semen. In a number of fertile bulls the following deviations were found: a. the presence of quite a lot of fructose in the spermatozoa;

b. the presence of glucuronic acid and / of other foreign compounds in the spermatozoa or in the plasma;

c. an elevated pH in the seminal plasma some 2 to 3 hours after ejaculation;

d. a low phenylalanine‐α ‐ketoglutarate transaminase activity in the whole semen (the spermatozoa had been disrupted by freezing).

4. Investigation of the presence of reducing aldehydes (glycolaldehyde and glyceraldehyde) inside the spermatozoa.

The determinations mentioned under 1, 3c and 3d can easily be carried out in the laboratories of each District Animal Health Service and of the A.I. stations; the same is true of the occurrence of amino acids in the seminal plasma and of fructose and aldehydes inside the spermatozoa if facilities are available for electrophoresis and chromatography.     

The Structure of the Spermatozoon of Liza Dumerili (Teleostei) With Notes on Spermiogenesis

The structure of the sperm of Liza dumerili was studied by light microscopy and scanning and transmission electron microscopy.

The sperm have a kidney-shaped nucleus. The “hilus” faces posteriorly and the proximal centriole is situated within the nuclear pit. Nuclear rotation takes place during spermiogenesis and the sperm are therefore related to those of other teleosts showing Type I spermiogenesis. No acrosome is evident. The midpiece is small but distinct and contains four spherical mitochondria. The flagellum enters the midpiece eccentrically and the axoneme runs obliquely towards the distal centriole to which it is connected. The flagellum conforms to the 9 + 2 flagellar pattern.     

Growth and reproduction of two molluscs from an exposed sandy beach

Populations of a gastropod, Bullia rhodostoma, and a bivalve, Donax sordidus, were monitored quantitatively over one year on an exposed sandy beach which supports a rich macrofauna. B. rhodostoma had a single reproductive season with copulation in early summer. Growth was slow and is described by a Von Bertalanffy growth curve. The annual mortality rate was very low, - 0,34. Production was estimated and a P/B ratio of 0,94 obtained. A minimum estimate for production by reproduction gave a P_R/B of 0,06. The average calorific value was 19,34 kJg D. sordidus appeared to have two spawning seasons and settlements in late winter and late summer. Growth was rapid and mortality moderate - 0,72. Steady state P/B was estimated to be 1,78. The mean calorific value was 18,84 kJg All of these values for both species are compared to those obtained on a nearby sheltered beach shich has a poor macrofauna.