N2O-Freisetzung auf gemähtem Dauergrünland in Abhängigkeit von Standort und N-Düngung

N₂O Emissions from True Meadows Dependent on Location and N Fertilization Agricultural production is thought to be a main anthropogenic emitter of nitrous oxide (N₂O), which contributes to global warming and the destruction of the ozone layer. There is still considerable uncertainty about the amount of N₂O emission, and the site‐specific parameters that affect N₂O emission. From October 1995 until March 1998 experiments were conducted at established field plots (true meadows) at three different sites, i.e. low mountain range (Eifel), lowland (Niederrhein), and moist meadows (Münsterland). Plots were fertilized with calcium ammonium nitrate (CAN) at nitrogen equivalents ranging from 0 to 360 kg N ha^–1. N₂O fluxes were measured throughout the whole year using the closed‐chamber method. In addition, data on temperature, water‐filled pore space and precipitation were collected. N₂O emission rates (mg N₂O‐N ha^–1 h^–1) were highest either after fertilizer application or in winter during frost, depending on the experimental site and N dosage. The annual amount of N losses due to N₂O emission was dependent on the experimental site and the type and dosage of fertilizer. Disregarding the 360 kg N ha^–1 level of the CAN treatments, the N losses in this experiment were less than 1.5 kg N₂O‐N ha^–1 yr^–1. At low fertilizer dosage there was no reliable correlation between the amount of N that was applied and the amount of N₂O that was emitted. However, with high fertilizer levels the N₂O emissions increased gradually. Finally, N₂O emissions were more influenced by the amount of CAN than by the site.     

Experimental control of the process of lead absorption and deposition in domestic ducks

A trial was conducted with 40 domestic ducks of the White Pekin breed at the age of 40 days: thirty pieces of lead shot were introduced as a single dose in the gizzard. The process of lead resorption and deposition was found not to be significantly influenced by the therapeutic treatments nor changes in the composition of feed. A week after the administration of shot a significant increase was recorded in the content of lead to 4.32 mg in liver, to 11.36 mg in kidney and to 1.15 mg in muscle (the respective values for the control animals were 0.07, 0.11 and 0.06 mg per kg). At the end of the trial after three weeks of treatment and administration of experimental diets, no significant differences were recorded in lead content in liver, kidney and muscle between the untreated and treated ducks nor ducks fed experimental diets.     

Genetic variation for tolerance or resistance to barley yellow dwarf virus in durum wheat

Summary One durum wheat line (Triticum durum), cv. 82PCD476, with useful BYDV tolerance or resistance, was singled out of 5 152 lines evaluated between 1979 and 1986. A few other lines such as cv. Boohai and cv. 12th IDSN 227, slightly inferior to cv. 82PCD476, also showed some value. With an hybrid of cv. 12th IDSN227 with the susceptible cv. 84PCY-S531, broad-sense heritability values of 0.37–0.41 were obtained for symptoms and a heritability value of 0.55 was obtained for the total weight of spikes. The weight of spikes was considered as a good indicator of wheat tolerance to BYDV. Although BYDV resistance or tolerance genes are not very common in durum wheat, sources of heritable resistance could be found. However, the resistance ofT. aestivum to BYDV was superior to the one found inT. durum.Cintribution no. 323     

Molecular genetic studies of the "Einsiedler" horse population

In this study it was investigated whether the "Einsiedler" warmblood horse, a historically old horse population from central Switzerland (Abbey of Einsiedeln), is distinguishable from micellaneous horse breeds, using molecular genetic techniques. The breeding history of Einsiedler horses is characterised by systematic line breeding through the dams. Therefore, two Einsiedler dam lines (N = 28), going back to the middle of the 19th century according to pedigree entries, were the focus of the survey. Random samples of diverse warmblood horse populations, but also samples from more distinct types of horse breeds, served as comparison populations (N = 52).Variation in the mitochondrial genome appeared to be only partially informative to demarcate the studied horses, as horses of distinct breeds may share identical mtDNA sequence fragments. Both dam lines revealed haplotypes commonly found in Iberian horse breeds. This is to take as an indication on the genetic origin of Einsiedler horses. Furthermore, the Klima dam line held a homologous mtDNA sequence fragment with E. ferus przewalskii. Therefore, this seems to be a phylogenetically old haplotype. The analysis of microsatellite loci revealed that horses from the two Einsiedler dam lines were in fact distinguishable from more distinct types of horses, but not from closely related European warmblood horse breeds and English thoroughbred.     

Superovulation beim Rind: Hormonprofile bei Stimulation mit Serum-gonadotropin (PMSG) bzw. hypophysärem FSH*)

Contents: Superovulation in cattle: Hormonal profdes during superovulation with PMSG or pituitary FSH.: Hormonal profiles for LH, FSH, PMSG, progesterone in peripheral blood and oestrogens in urine during superovulation with PMSG (1500–3100 IU i. m.) or pituitary porcine FSH (5 mg i.m. 2 times daily for 5 days) were evaluated radioimmunologicaly. Two days after the begin of treatment luteolysis was induced by means of 0.5 mg Estrumat® i. m. The experiments were performed with 14 heifers and 2 cows. Blood samples were taken in 6 or 12 h intervals. Preovulatory LH and FSH peaks occurred coinciding with the onset o f oestrus in good responding animals instead of a few hours later, as in weakly responding animals or during normal oestrous cycle. PMSG could be still measured in peripheral blood 10 days after application. Preovulatory gonadotropin peaks are preceded in good responding animals by clear oestrogen peaks contrary t o weak responding ones. Progesterone concentrations of good responding animals increase faster after the preouulatory LH peak and reach higher absolute values compared t o bad responding ones or during normal oestrous cycle. Furthermore there was a clear difference in progesterone values between both stimulation methods. Progesterone concentrations after induction of superovulation with PMSG are significantly higher f o r about the same number of corpora lutea as after stimulation with pituitary FSH. For judgement of the success of stimulation the determination of progesterone can be considered as parameter. From the hormonal profiles no conclusion can be drawn why some animals don't respond to the stimulation.     

The effects of growth substances and photoperiod on the development of shoot apices of Vitis cultured in vitro

‘Rougeon’ grapevines were recovered from shoot apices using in vitro culture. Shoot development from apices 0.5–1 mm in length, which contained 2–4 leaf primordia was obtained with 5 × 10^?6M benzylaminopurine and 5 × 10^?7M naphthaleneacetic acid (NAA) under a 10-hour photoperiod, but not under continuous light, in a 15-hour photoperiod, or in darkness. At least one vigorous shoot was produced by 100% of the cultures.Rooting of these shoots was induced under the same photoperiod with the same basal culture media containing only 10^?7 M NAA. Roots were produced by 91% of the cultures. Zero-, 16- or 24-h photoperiods were ineffective in promoting root development.Rooted plantlets were transferred into soil with 80% of them surviving. The grapevines were allowed to reach an average length of 2 m in a growth chamber before growth conditions were modified to induce dormancy. Vines were planted in a vineyard; after 2 growing-seasons we were unable to distinguish the micropropagated vines from ‘Rougeon’ vines propagated in the standard manner, on the basis of fruit or vegetative morphology.     

Direct diagnosis of herpesvirus in equine foetal organs by means of electron microscopy

A technique for direct electron microscopy of EHV-1 infected foetal organs is described. Of 124 cases shown to be positive by fluorescent antibody procedurees, 67 (54%) were positive by direct electron microscopy.