The Uptake and Distribution of 15N enriched Nitrate by three Rootstock Cultivars grafted to Chenin blanc

The uptake and distribution of nitrogen by the rootstocks 99R, 101-14 Mgt and 140 Ruggeri grafted to Chenin blanc in sand culture, were determined using 15N enriched potassium nitrate. The K15N03 was applied at the end of rapid shoot growth and the vines were sampled at veraison. Although vines grafted on 99R showed less aerial- and root growth than those ~n 101-14 Mgt and 140 Ruggeri, nitrogen was absorbed equally well by all three rootstocks.The distribution of newly absorbed nitrogen could be accurately determined by means of 15N, and at veraison more than half of newly absorbed N was found in the leaves and shoots, and about 15% in the bunches. It was clear that nitrogen which accumulated in the bunches during the period of investigation, was derived primarily from previously assimilated N in the roots and mature wood

Liming and Choice of Rootstocks as Cultural Techniques for Vines in Acid Soils

The effect of soil acidity on the performance of Chenin blanc vines grafted on 15 rootstock cultivars was determined in a pot experiment by liming a typically acid soil at pH (KCI) 4,1 (Control), to a pH of 5,0 (Treatment 1) and pH 6,0 (Treatment 2). On average the shoot masses of vines from Treatment 1 and Treatment 2 were respectively 27% and 870/o higher than those of the control. Root masses were increased by 11 O/o and 320/o respectively, indicating that the locally accepted norm of liming acid soils to a pH of 5,0 or to a point where exchangeable aluminium is decreased to less than 0,2 meq/100 g of soil, may be insufficient for most rootstocks. The beneficial effect of lime on the performance of vines could have been partly due to an improvement in the structure of the soil as indicated by lower mechanical resistances of the limed soils. The detrimental effect of soil acidity on the performance of vines could be reduced by the correct choice of rootstocks. The cultivars 140 Ruggeri, USVIT 8-7, 110 Richter, 99 Richter and USVIT 2-1 were best suited for use on acid soils while 101-14 Mgt, 44-53 Malegue, S04 , Rupestris du Lot and USVIT 3-6 proved less suitable for the acid soil used in this investigation

Seasonal Uptake of Nutrients by Chenin Blanc in Sand Culture: II. Phosphorus, Potassium, Calcium and Magnesium

The seasonal uptake of phosphorus, potassium, calcium and magnesium as well as their distribution in the vine were determined for Chenin blanc/99R vines grown in sand culture under South African climatic conditions. Phosphorus absorption showed two distinct peaks-the first ranging from after bud burst until veraison, and the second, less prominent, from about five weeks after harvest into the leaf fall period.Potassium was absorbed from about three weeks after bud burst until four to five weeks after harvest. No potassium was absorbed during leaf fall. Active absorption of calcium started after bud burst and continued until veraison. A second, less pronounced absorption period occurred during the six weeks before leaf fall. Similarly, absorption of magnesium started after bud burst and continued until veraison, after which the absorption rate decreased and ceased with the onset of leaf fall. A significant amount of the phosphorus and potassium absorbed during the post harvest period was retained in the permanent parts of the vine. However, most of the post harvest calcium and magnesium gains were lost through leaf fall. Most of the calcium retained by the permanent parts of the vine, was stored in the bark. There was an apparent translocation of potassium from the leaves to the permanent structure of the vine during leaf fall. This was not noticeable for any of the other three nutrients

Nutrient Consumption by Chenin Blanc grown in Sand Culture and Seasonal Changes in the Chemical Composition of Leaf Blades and Petioles

The seasonal utilization of N, P, K, Ca and Mg by the various aerial and underground organs of bearing Chenin blanc/99R grown in sand culture under South African climatic conditions was tabulated. During the production of one ton of grapes, the bunches accumulated 1,39; 0,25; 1,98; 0,17 and 0,09 kg N, P, K, Ca and Mg respectively, the permanent parts of the vine accumulated a further 0,73; 0,10; 0,19; 0,14 and 0,08 kg, and the vegetative growth (leaves plus prunings) accumulated 1,77; 0,37; 0,88; 1,70 and 0,43 kg. Appreciable seasonal changes were found in the chemical composition of both leaf blades and petioles. The petioles showed a reasonably stable composition during the month following bloom verifying the results of other workers, and samples for analyses should, therefore, be collected at this stage. However, the nutrient concentrations in the leaf blades remained unstable. The nutrient export figures obtained in this experiment may be used in conjunction with occasional petiole analyses as a basis for fertilizer recommendations. However, in the case of petiole analyses reliable norms are still lacking

Seasonal Uptake of Nutrients by Chenin blanc in Sand Culture: I. Nitrogen

The seasonal uptake and the distribution of nitrogen were determined for Chenin blanc/99R, grown in sand culture under South African conditions. Whole vines were sampled 14 times in the course of one year. Two distinct absorption peaks were found-the first starting after bud burst and lasting up to veraison, while the second extended from harvest into the leaf fall period. The amount of nitrogen absorbed during the second (post harvest) period amounted to 34% of the total for the season, and most of this was stored in the roots.The amount of nitrogen removed by the crop (1,39kg/ton of grapes) compared well with relevant literature, but the amount of nitrogen in leaves and canes associated with this, differed from results obtained in other countries

The Effect of Conventional Fertilisation on the Growth and Yield of Palomino Vines on Fertile Soil

The effect of two levels of conventional fertiliser applications on the performance of Palomino grapes on the fertile soil of the Olifants River region was studied. Soil, leaf and must analyses, and shoot and crop mass were used as indicators offertiliser response. A tendency towards improved shoot mass but no significant effect on crop mass due to fertilisation was found. Leaf and must analyses did not reflect treatments, probably because of a natural luxurious P and K supply in the soil concerned, which was calculated to be sufficient for at least 20 years. However, the soil seemed to be on the borderline in its N supplying capabilities for a production level of 40 t/ha. The importance of phylloxera as a growth and production limiting factor in comparison with fertilisation was demonstrated. No P or K fertilisation is recommended for these soils, and a yearly application of 90 kg N/ha is suggested as a guideline for N fertilisation

Molecular phylogenetics reveals a complex history underlying cryptic diversity in the Bush Squeaker Frog (Arthroleptis wahlbergii) in southern Africa

Throughout the Miocene, the African landscape underwent broad climatic shifts that profoundly influenced the distribution of fauna and flora. Since the late Miocene, these shifts have created a landscape in southern Africa that is strongly characterised by savanna and arid environments. Forests persist in small fragments, primarily in mountainous or heterogeneous landscapes. Arthroleptis wahlbergii is a small frog endemic to eastern South Africa that has presumed low dispersal ability. Because of its preference for forests, the dynamics of forests since the late Miocene in this region might have promoted diversification within A. wahlbergii. To investigate whether habitat fragmentation might have driven divergences among populations, we carried out species distribution modelling and population level and phylogenetic analyses using two genetic loci (16S, mitochondrial; RAG-1, nuclear) sequenced for 48 individuals from 14 forests across the c. 500 km range of this species. There is substantial population level structuring within A. wahlbergii, however the structure does not relate to forest types or catchments. We instead propose that the structure is a result of dynamic and idiosyncratic changes in forest connectivity over the Pleistocene. We identified two geographically circumscribed clades, the northern of which corresponds to true A. wahlbergii. The southern clade corresponds to populations from which Arthroleptis wageri FitzSimons, 1930 was described. This has long been considered a synonym of A. wahlbergii, but our molecular phylogenetic and distribution modelling supports recognising A. wageri as a distinct species

Editorial Cartoons and Propaganda Posters of the Union of South Africa’s pro-war press during the First World War; 1914-1918

Thesis (MA)--Stellenbosch University, 2016.ENGLISH SUMMARY: The thesis investigates how editorial cartoons and propaganda posters of the pro-war South African press were employed during the First World War to recruit soldiers from British colonies. A brief discussion that identifies various forgotten aspects of South African involvement in the First World War traces the history of this country’s involvement in the 1914-1918 conflicts in Europe. This discussion outlines the socio-political background against which a selection of cartoons and posters were developed and published, while it also contextualises the study. Five examples of jingoist editorial cartoons and two propaganda posters are carefully analysed within a semiotic theoretical framework, ultimately to explain and inform on the illustrations, book art objects, installations, and various other art works constituting syntheses in an investigation that integrates theory and practice.AFRIKAANS OPSOMMING: Die tesis ondersoek die maniere waarop koerantspotprente en propaganda plakkate deur die pro-oorlog Suid-Afrikaanse pers gebruik is om gedurende die Eerste Wêreldoorlog soldate vanuit die Britse kolonies te werf. ‘n Kort bespreking wat verskeie vergete aspekte van Suid-Afrikaanse betrokkenheid in die Eerste Wêreldoorlog identifiseer volg ook die geskiedenis van hierdie land se betrokkenheid in die 1914 – 1918 konflikte in Europa. Hierdie bespreking teken die sosio-politieke agtergrond waarteen ‘n seleksie van spotprente en plakkate ontwikkel en gepubliseer is, terwyl dit ook die studie kontekstualiseer. Vyf voorbeelde van jingoïstiese koerantspotprente en twee voorbeelde van propaganda plakkate word versigtig ontleed binne ‘n semiotiese teoretiese raamwerk om uiteindelik lig te werp op die illustrasies, boekkuns objekte, installerings en verskeie ander kunswerke wat sintese in die ondersoek verteenwoordig in ‘n studie wat teorie en praktyk integreer

Characterization and Oxidative Addition Reactions of Different Rhodium and Iridium Triazolato Complexes

A number of different rhodium(I) and iridium(I) triazolato complexes and their oxidative addition products (triazolate = 3,5-bis(pyridine-2-yl)-1,2,4 triazolate (bpt–) and 4-amino-3,5-bis(pyridine-2-yl)-1,2,4-triazolate (bpt-NH–)) were prepared and characterized by means of IR and 1HNMR spectroscopy, elemental analysis and computational chemistry methods. The oxidative addition reactions of these complexes with iodomethane in different solvents indicated simple second-order kinetics with the faster reactions in the more polar solvents (1.44(7) × 10–2 L mol–1 s–1 in dichloromethane compared with 9.2(5) × 10–4 L mol–1 s–1 in benzene for iridium bpt-NH). 1HNMRdata and density functional theory calculations illustrate that the coordination of the metal centre in [M(bpt-NH)(cod)] (M = Rh or Ir) occurs via the amine moiety and a nitrogen of a pyridine ring.Keywords: Rhodium(I), Iridium(I), Triazole, Cyclooctadiene, Oxidative Addition, Methyl Iodide, DFTAttached PDF and Supplementary Fil

Calculation aspects of the European rebalanced basket option using Monte Carlo methods : valuation

CITATION: Van der Merwe, C. J. & Conradie, W. J. 2012. Calculation aspects of the European rebalanced basket option using Monte Carlo methods : valuation. Orion, 28(1):1-18, doi:10.5784/28-1-104.The original publication is available at http://orion.journals.ac.zaExtra premiums can be charged to a client to guarantee a minimum payout of a contract on a portfolio that gets rebalanced on a regular basis back to fixed proportions. The valuation of this premium can be changed to that of the pricing of a European put option with underlying rebalanced portfolio. This article finds the most efficient estimators for the value of this path-dependant multi-asset put option using different Monte Carlo methods. With the help of a refined method, computing time of the value decreased significantly. Furthermore, Variance Reduction Techniques and Quasi-Monte Carlo methods delivered more accurate and faster converging estimates as well.http://orion.journals.ac.za/pub/article/view/104Publisher's versio