Korttermyn invloed van strawwe droogte op veldtoestand en waterverbruiksdoeltreffendheid van grasveld in die sentrale Oranje‐Vrystaat

Short‐term effect of severe drought on veld condition and water use efficiency of grassveld in the central Orange Free State. The impact of an intensive drought (1982/1983 and 1983/84‐growing seasons) on botanical composition, basal cover, mortality of grazing plants and water use efficiency (WUE) of veld in good, moderate and poor condition was identified. Increaser II species were apparently more capable of surviving drought than the Decreaser species. Under optimal soil moisture conditions the Decreaser species increased and the Increaser II species decreased. During the drought extensive grass mortality took place. Veld condition plays an important role in determining mortality during drought. Decreaser species have a high water requirement for optimal WUE, while Increaser II species can reach maximum WUE with less water. Under water stress conditions Increaser II species significantly (P≤0.01) do not use the water as efficiently as do Decreaser species. The WUE under water stress conditions for veld in good, moderate and poor condition was on average, during the study period, 0.90; 0.90 and 0.40 kg ha^?1 mm^?1, respectively, and towards under optimal water conditions, 2.47; 1.67 and 0.23 kg ha^?1 mm^?1, respectively.     

The effects of China’s growth slowdown on its provinces: Disentangling the sources

Since 2007, China's growth has fallen from around 10% to about 6%–7% per annum. This paper investigates the experience of this slowdown at the provincial level. We use a vector‐autoregressive modelling approach and annual data from 1978 to decompose each province's growth into various factors. We find that (a) all provinces experienced the slowdown; (b) there is considerable variation in this experience across provinces; (c) national factors dominate the provincial slowdown while province‐specific factors explain most of the interprovincial variation; (d) when the national factor is separated into supply and demand components, the supply component dominates.     

Ciliary photoreceptors with a vertebrate-type opsin in an invertebrate brain

For vision, insect and vertebrate eyes use rhabdomeric and ciliary photoreceptor cells, respectively. These cells show distinct architecture and transduce the light signal by different phototransductory cascades. In the marine rag-worm Platynereis, we find both cell types: rhabdomeric photoreceptor cells in the eyes and ciliary photoreceptor cells in the brain. The latter use a photopigment closely related to vertebrate rod and cone opsins. Comparative analysis indicates that both types of photoreceptors, with distinct opsins, coexisted in Urbilateria, the last common ancestor of insects and vertebrates, and sheds new light on vertebrate eye evolution.     

Uptake and Distribution of Lead (Pb) and Cadmium (Cd) in the Freshwater Crab,Potamonautes Perlatus (Crustacea) in the Eerste River,South Africa

This paper evaluates the effects of organic amendments and ironprecipitation on pore size distribution and mechanical resistancein sulphide mine tailings, as related to plant habitat requirements. Unaltered tailings, oxidised tailings collected from untreated, fertilized and sludge-amended plots in the field,and mixtures of unaltered tailings and organic amendments prepared in the laboratory, were analysed for pore size distribution. The organic amendments (sewage sludge, peat mossand paper mill sludge) were each applied at the rates of 0, 16 and 33% by volume. A difference in pore-size distribution between untreated and treated samples was shown in both field and laboratory samples. Both inorganic and organic amendments caused a decrease in pores holding water at soil water potentials–10 to –60 kPa, but increased the pores holding water at tensions below –60 kPa. This resulted in a decreased or unchanged content of plant available water (W_a) in all laboratory samples and in the fertilized field samples. Penetration studies in the field showed that additions of fertilizer, without any organic matter, had resulted in hardpans in the oxidised tailings that significantly increased themechanical resistance in the surface horizon. Thus, this studyindicates that the physical influence of the oxidation processestaking place in sulphide mine tailings can be magnified by additions of soil amendments. The aggregation of iron oxides and negatively charged particles such as organic substances orphosphate anions may cement the tailings, which can result inimpeded root growth.     

Conditioned feed aversion as a means to prevent tulp (Homeria pallida) poisoning in cattle

Conditioned feed aversion was investigated as a means to prevent tulp (Homeria pallida) poisoning in cattle on tulp-infested grazing. Aversion treatment with a combination of epoxyscillirosidin and lithium chloride together with a tulp-hexane extract, which served as identification factor for tulp, resulted in a significantly lower (P < 0.001) proportion of severe tulp poisoning. In a first trial where 21 averted and 21 non-averted control cattle were exposed to a tulp-infested grass pasture, only two of the averted cattle were severely poisoned compared to 13 of the non-averted control cattle. In a second trial, with cattle being exposed to a pure stand of tulp supplemented with maize residues, only two of 21 averted cattle were severely poisoned compared to 14 of 21 non-averted control cattle. Occurrence of mild tulp poisoning, however, did not differ much between averted and non-averted control cattle. The results show that conditioned feed aversion effectively restricted severe poisoning in cattle on tulp-infested grazing.     

Metastatic anaplastic adenocarcinoma suspected to be of mammary origin in an intact male rabbit (Oryctolagus cuniculus)

A 7-year-old, intact male, pet dwarf rabbit (Oryctolagus cuniculus) was presented for a ventral abdominal subcutaneous mass. Histolopathology of the resected mass was suggestive of a mammary adenocarcinoma. Six months later, the rabbit died from severe dyspnea. Necropsy showed recurrence of the original mass with hepatic and pulmonary metastasis of the anaplastic adenocarcinoma, suspected to be of mammary origin.     

Persistent vulvar hemorrhage secondary to vaginal hemangioma in dogs

Two young female dogs were presented with a chronic history of persistent vulvar hemorrhage. Vaginoscopy was ultimately used to locate bleeding vaginal masses near the urethral papilla. In both cases, episiotomy was performed to resect the mass, and hemangioma was diagnosed histologically. These tumors caused persistent vaginal bleeding; they were difficult to diagnose without vaginoscopy and lavage; and surgical excision was curative in at least one case.     

Die invloed van vog‐ en ontblaringsbehandelings in hidrologiese eenhede op natuurlike veld van die sentrale oranje‐vrystaat

Die invloed van al die kombinasies van twee intensiteite (3 en 6 cm ontblaringshoogtes) en twee frekwensies (een en vier keer per jaar) van ontblaring, is onder drie verskillende vogbehandelings, onder natuurlike veldtoestande, vir die periode Julie 1978 tot Junie 1981, ondersoek. Die invloed van die vog‐ en ontblaringsbehandelings is geëvalueer in terme van die basale bedekking, botaniese samestelling, fitomassaproduksie en waterverbruiksdoeltreffendheid (WVD: Is die fitomassa geproduseer in verhouding tot die evapotranspirasie).

Die verskillende vogbehandelings waaraan die veld onderwerp is, het meegebring dat daar aan die einde van die 1980/81‐seisoen hoogs betekenisvolle verskille in basale bedekking en botaniese samestelling tussen die drie vogbehandelings voorgekom het.

Vog toon die grootste invloed op weiveldproduksie van al die veranderlikes wat toegepas is. Die intensieteit en frekwensie van ontblaring het die produksie tot ‘n mindere mate beinvloed.

Die waterverbruiksdoeltreffendheid van die grasse onder vogbehandeling 1, naamlik normale reënval, het toegeneem met ‘n afname in ontblaringsintensiteit. Onder vogbehandeling 2, naamlik optimale grondvogtoestande, neem die WVD van die grasse toe met ‘n toename in ontblaringsfrekwensie. Hoe strawwer ontblaar is (3 cm hoogte in plaas van 6 cm hoogte) onder optimale grondvogtoestande, hoe hoër is die waterverbruiksdoeltreffendheid.     

Studies on Haemonchus contortus. II. The effect of abomasal nematodes on subsequent challenge with H. contortus

Fifty-thousand infective larvae of Trichostrongylus axei dosed to 7-9-month-old Merinos protected them against a subsequent challenge with 50 000 infective larvae of Haemonchus contortus. Protection varied with the period between an initial dosage of T. axei and challenge with H. contortus as follows: After 90 days it was more than 80% effective in more than 80% of sheep; at 119 and 180 days there was still a significant reduction in the numbers of H. contortus recovered (P < 0,05 and P < 0,001, respectively). Prior infestation with either Ostertagia circumcincta or with Haemonchus placei was ineffective against challenge with H. contortus.     

Discrimination between organically and conventionally grown winter wheat farm pair samples using the copper chloride crystallisation method in combination with computerised image analysis

Organic and conventional winter wheat farm pair grain samples were tested with the copper chloride crystallisation method and submitted to computerised image analyses followed by pattern recognition and classification with multivariate statistical tools.Appropriate discriminant analyses (DA) models were established. Depending on the analysed region of interest up to 100% of “unknown” samples could be correctly predicted using the DA models.