Problems in breeding and cytology of sugar cane

In connection with the increase of chromosome number found in species hybrids of Saccharum the author studied embryo-sac development within several Saccharum froms from early stages of meiosis in the embryo-sac mother cells to stages where fertilization already had taken place.Normally by meiosis within E M C's a row of four haploid megaspores is formed from which the innermost, the chalazal megaspore, develops into an embryo-sac and the other three degenerate.Haploid embryo-sacs, thus formed, may occur in Saccharum. Frequently however, in Saccharum endo-duplication takes place, that is splitting of the chromosomes within the nucleus of the chalazal megaspore, through which the chromosome number is increased.It is described how within Saccharum by this phenomenon embryo-sacs may be formed with diploid and tetraploid chromosome numbers and with numbers between haploid and diploid.The increase of chromosome number, observed in the young megaspore after meiosis, could be confirmed by counting the chromosomes of dividing nuclei within young embryo-sacs.Chromosome numbers found in dividing zygotes and endosperm nuclei within fertilised embryo-sacs also pointed to the occurrence of egg-cells and polar nuclei that must be haploid, diploid and tetraploid.The significance of this research in relation to plant breeding will be discussed in Part V.     

Die Bekämpfung der Rübenfliege (Pegomyia hyoscyami Pz.)mit Fluornatrium und Kieselfluornatrium

Ohne Zusammenfassung (Ref.) aus der Biologischen Reichsanstalt für Land- und Forstwirtschaft.     

Zur Epidemiologie der Rübenfliege (Pegomyia hyoscyami Pz.)

Ohne Zusammenfassung Biologische Reichsanstalt für Land- und Forstwirtschaft, Fliegende Station Stralsund. Mit 1 Abbildung.     

Dystocia and Fetotomy Associated with Cerebral Aplasia in a Greater One‐horned Rhinoceros (Rhinoceros unicornis)

The captive greater one‐horned rhinoceros population consists of 176 animals. Since 1971, a total of 226 calves were born into this captive population. However, 24% of the offspring born were either stillborn or did not survive the first 3 months. The causes for this high rate of stillbirth and neonate mortality have not yet been documented. Here, we report on the veterinary management of a dystocia and foetotomy resulting from a malpositioned greater one‐horned rhinoceros foetus. The dead foetus presented with a forelimb flexed at the shoulder joint, with all other joints extended. The foetus was dissected into five parts and extracted during two anaesthesias on two consecutive days. The dam recovered fully and came into oestrous 31 days after surgery. Post‐mortem and CT examination of the malformed foetal head revealed cranioschisis with cerebral aplasia and cerebellar hypoplasia. The cerebral aplasia presented here and in other recent cases suggests that neural tube defects and cranial malformations may be associated with more captive rhinoceros stillbirths than previously considered. Epidemiologic studies of these phenomena and possible nutritional deficiencies or hereditary defects are warranted.     

Administration of Thyroxine Affects the Morphometric Parameters and VEGF Expression in the Uterus and Placenta and the Uterine Vascularization but does Not Affect Reproductive Parameters in Gilts During Early Gestation

The aim of this study was to evaluate the effects of thyroxine administration on morphometric parameters, expression of vascular endothelial growth factor (VEGF) and vascularization in the uterus and placenta and reproductive parameters in gilts at 70 days of gestation. At 150 days of age, i.e., before first heat, 20 gilts were randomly divided into two experimental groups: treated (n = 10) and control (n = 10). The treated group received a daily dose of 400 μg of l ‐thyroxine (T₄) in their diet until slaughter and the control group received only typical meals. Before artificial insemination, blood was collected to determine plasma total T₄. The gilts were inseminated in the second oestrus and slaughtered at 70 days of gestation. The foetal thyroid follicular epithelium height, number, size and weight of foetuses; foetal myogenesis, corpora lutea number, embryonic mortality rate, uterine weight, placental weight and placental fluid volume were measured. Histomorphometric and immunohistochemical analysis of uterus and placenta were determined. The averages of all variables were compared by the Student’s t‐test. The gilts treated with thyroxine showed significant increase of plasma total T₄. At 70 days of gestation, the heights of the trophoblastic epithelium, endometrial epithelium and endometrial gland epithelium were significantly higher in the group treated with T₄. The expression of cytoplasmatic and nuclear VEGF in trophoblastic cells and the number of blood vessels per field in endometrial stroma were significantly higher in the gilts treated with T₄. No other significant differences between groups were obtained with respect to other parameters (p > 0.05). We conclude that oral administration of T₄ up to 70 days of pregnancy in gilts affects the morphometric parameters, the expression of placental VEGF and the uterine vascularization but does not affect reproductive parameters in gilts during early gestation.     

Elimination of viruses and hypersensitivity to potato virus Y (PVYo) in an important sudanese potato stock (Zalinge)

Viruses that infect naturally an important Sudanese potato stock Zalinge were detected using enzyme-linked immunosorbent assay, immunosorbent electron microscopy and sap-inoculation to test plants. All of the 19 plants of Zalinge tested were infected with potato leaf roll virus (PLRV) and potato virus S (P VS), and five plants also with potato virus X (PVX). No potato virus Y (PVY), A (PVA) nor M (PVM) were found. The viruses were eradicated with thermo and chemotherapy using standard procedures. The combination of both therapies did not result in any virus-free plants, but resulted in poor plant survival. Thermotherapy reduced the incidence of PLRV and PVS by 45% and 50%, respectively, and one virus-free plant was obtained. It grew vigorously in the greenhouse, was symptomless and had a significantly increased tuber yield compared to the virus-infected plants. Following sap-inoculation with PVY^O, Zalinge showed mosaic symptoms, developed necrosis in the leaves and stem and died 14 days post-inoculation. However, the plants of Zalinge infected with PVY^N remained symptomless, which suggested that hypersensitivity was specific to PVY^O. The fast development of lethal necrosis following infection with PVY^O may contribute to the low incidence of PVY in Zalinge in the field in Sudan.     

Short-term and long-term effects of bacterivorous nematodes and nematophagous fungi on carbon and nitrogen mineralization in microcosms

A microcosm experiment was carried out to quantify the effects of organisms at various trophic levels on C and N mineralization after the addition of crop residues to arable soil. The effects of the bacterivorous nematodes Rhabditis sp. and Acrobeloides bütschlii and of the nematophagous fungi Arthrobotrys oligospora und Drechmeria coniospora on soil respiration and N mineralization were measured over 6 months at 20°C. In the presence of nematodes, C mineralization was increased during the first month and subsequently reduced; N mineralization was increased during the first 2 months and then reduced. The results support the assumption that nematodes influence C mineralization mainly indirectly by affecting bacterial activity, and N mineralization mainly directly by mineralizing bacterial biomass. A. oligospora contributed directly to C mineralization. The effect of both fungi on N mineralization was indirect and resulted from the reduction in the numbers of nematodes. The results showed that the effects of nematodes and nematophagous fungi and the mechanisms behind the effects may vary strongly in time, and are correlated with the type of organic matter decomposed.Work was carried out at the DLO Research Institute for Agrobiology and Soil Fertility, Haren     

Carbon dioxide evolution from wheat and lentil residues as affected by grinding,added nitrogen,and the absence of soil

Summary A study was conducted to determine the effects of grinding, added N, and the absence of soil on C mineralization from agricultural plant residues with a high C:N ratio. The evolution of CO₂ from ground and unground wheat straw, lentil straw, and lentil green manure, with C:N ratios of 80, 36, and 9, respectively, was determined over a period of 98 days. Treatments with added N were included with the wheat and lentil straw. Although the CO₂ evolution was initially much faster from the lentil green manure than from the lentil or wheat straw, by 98 days similar amounts of CO₂ had evolved from all residues incubated in soil with no added N. Incubation of plant residues in the absence of soil had little effect on CO₂ evolution from the lentil green manure or lentil straw but strongly reduced CO₂ evolution from the wheat straw. Grinding did not affect CO₂ evolution from the lentil green manure but increased CO₂ evolution from the lentil straw with no added N and from the wheat straw. The addition of N increased the rate of CO₂ evolution from ground wheat straw between days 4 and 14 but not from unground wheat straw, and only slightly increased the rate of CO₂ evolution from lentil straw during the initial decomposition. Over 98 days, the added N reduced the amounts of CO₂ evolved from both lentil and wheat straw, due to reduced rates of CO₂ evolution after ca. 17 days. The lack of an N response during the early stages of decomposition may be attributed to the low C:N ratio of the soluble straw component and to microbial adaptations to an N deficiency, while the inhibitory effect of N on CO₂ evolution during the later stages of decomposition may be attributed to effects of high mineral N concentrations on lignocellulolytic microorganisms and enzymes.     

Schädlingsbekämpfung mit flüssigen Arsenködern in Deutschland

Ohne Zusammenfassung Biologische Reichsanstalt für Land- und Forstwirtschaft, Fliegende Station Stralsund.