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Defoliation effects on resource allocation in Arizona cottontop (Digitaria californica) and Lehmann lovegrass (Eragrostis lehmanniana)
Item type: Journal Article • Journal: Journal of the Grassland Society of Southern Africa • Authors: JerryR. Cox --- , Republic of South Africa M. Giner‐Mendoza --- , Mexico A.K. Dobrenz --- Plant Sciences Department, United States of America MarieF. Smith --- , Republic of South AfricaArizona cottontop (Digitaria californica), a bunchgrass native to the Chihuahuan and Sonoran Deserts in North America, and Lehmann lovegrass (Eragrostis lehmanniana), a bunchgrass introduced to the southwestern USA from southern Africa, were defoliated and examined for above‐ and below‐ground productivity,... -
Influence of sub-optimal imbibition temperatures on seed vigour and respiration in maize (Zea mays L.)
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: H.A. van de Venter --- , N. Grobbelaar --- ,Germination and coleoptile growth of nine seed lots of maize (representing seven cultivars) were studied at 25°C (constant), 13°C (constant) and also at 7°C (7 days) followed by 25°C. Relative germination response to sub-optimal temperatures reflected relative differences in germination... -
Germination rate of maize (Zea mays L.) kernels. II. Relationships with respiration rate and adenosine triphosphate content
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: H.A. van de Venter --- , Republic of South Africa Rentia Hoffman --- , Republic of South Africa S. de Meillon --- , Republic of South AfricaGermination rate of freshly harvested, undeteriorated seed lots of maize was found to be positively correlated with rate of oxygen uptake of kernels and adenosine triphosphate (ATP) content of embryos, at 6 and 12 h of incubation. Respiration rate was... -
Bepaling van donkerrespirasie by mielies (Zea mays L.)
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: W.H. du Preez --- Landboufakulteit, Republiek van Suid-Afrika J.J. Human --- Landboufakulteit, Republiek van Suid-Afrika L.P. de Bruyn --- Landboufakulteit, Republiek van Suid-AfrikaTwee mieliecultivars wat in potte onder glashuistoestande met optimale watervoorsiening gekweek is, is gedurende die agtblaarstadium en stuifmeelstort tot baardverskyning aan stremming onderwerp deur watertoediening te weerhou. Die CO2-uitvloeitempo is op sekere tye gedurende die nagperiode gemonitor. Hierdie waardes het... -
The effect of acetanilide herbicides on photosynthesis and respiration in isolated hypocotyl-epicotyl cells from three Phaseolus taxa
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: E. van Rensburg --- , Republic of South Africa L.P. van Dyk --- , Republic of South Africa G.H. de Swardt --- , Republic of South AfricaThe effect of alachlor [2-chloro-N-(2,6 diethylphenyl)-N-methoxymethyl) acetamide], metolachlor [2-chloro-N- (2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide] and acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl) acetamide] on photosynthesis and respiration of isolated 10-day-old hypocotyl-epicotyl cells from three Phaseolus taxa was investigated. Herbicide concentrations of 1×10−12, 1×10−10, 1×10−8, 1×10−6,1×10−4 and 5×10−3 M... -
Seed development and maturation in edible dry bean (Phaseolus vulgaris L.) cv. Teebus
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: H.A van de Venter --- Department of Botany, Republic of South Africa I. Demir --- Department of Botany, Republic of South Africa S. de Meillon --- Department of Botany, Republic of South Africa W.A. Loubser --- National Department of Agriculture, Republic of South AfricaA study of seed development and maturation in edible dry bean cv. Teebus was conducted on field-grown plants. Mass maturity (maximum seed dry mass) occured 43 days after flowering (DAF) when seed moisture content was 52%. Harvest maturity (at a... -
Rootstock-dependent soil respiration in a citrus orchard
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: N. Keutgen --- Department of Horticultural Science, Republic of South Africa M. Huysamer --- Department of Horticultural Science, Republic of South AfricaSoil respiration is a major contributor to the carbon flux in apple orchards, but very little data exist for citrus. Daytime soil respiration, grass respiration, and grass photosynthesis were recorded in a ‘Nules’ clementine (Citrus reticulata Blanco) orchard on ‘Carrizo’... -
Bio-stimulatory properties in seeds of plants from the families Caryophyllaceae and Fabaceae with application potential in agriculture
Item type: Journal Article • Journal: South African Journal of Plant and Soil • Authors: J.C. Pretorius --- , South Africa A. Du Plessis --- , South Africa E. van der Watt --- , South AfricaA comparative investigation into the bio-stimulatory activity of seed suspensions from two South African plant species belonging to each of the families Caryophyllaceae and Fabaceae were conducted using ComCat®, a commercially available bio-stimulant, as a positive control. These included Acacia... -
Quantitative aspects of oxygen and carbon dioxide exchange through the lungs in Ocypode ceratophthalmus (Crustacea: Decapoda) during rest and exercise in water and air
Item type: Journal Article • Journal: African Journal of Aquatic Science • Authors: WJ van Aardt --- School of Environmental Sciences and Development, South AfricaGhost crabs Ocypode ceratophthalmus were exercised in air and water to measure CO2 and O2 exchange rates using the method of instantaneous measurements of oxygen consumption rate (MO2) where applicable. Average heart rate increased from 100 to nearly 400 pulses... -
Metabolic adaptations and reduced respiration of the copepod Calanoides carinatus during diapause at depth in the Angola-Benguela Front and northern Benguela upwelling regions
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: H Auel W Hagen W Ekau HM VerheyeStage C5 copepodids and adult females of the herbivorous copepod Calanoides carinatus were sampled in the Angola-Benguela frontal region and northern Benguela upwelling area off Namibia in February–March 2002, using a multiple opening/closing net system. Respiration rates of C5s collected... -
The effect of positive end-expiratory pressure on pulse pressure variation
Item type: Journal Article • Journal: Southern African Journal of Anaesthesia and Analgesia • Authors: FJ Smith --- Department of Anaesthesiology, School of Medicine, Faculty of Health Sciences, M Geyser --- Department of Anaesthesiology, School of Medicine, Faculty of Health Sciences, I Schreuder --- Department of Anaesthesiology, School of Medicine, Faculty of Health Sciences, PJ Becker --- Biostatics Unit,Objectives: To determine the effect of different levels of positive end-expiratory pressure (PEEP) on pulse pressure variation (PPV). -
Hypoxia tolerance of introduced Nile perch: implications for survival of indigenous fishes in the Lake Victoria basin
Item type: Journal Article • Journal: African Zoology • Authors: Pamela J. Schofield --- Department of Zoology, U.S.A. Lauren J. Chapman --- Department of Zoology, U.S.A.The introduction of predatory Nile perch (Lates niloticus) into the Lake Victoria basin coincided with a dramatic decline in fish diversity. However, remnant populations of indigenous fishes persist in lagoons and satellite lakes separated from the main lakes by extensive... -
Are wild African lungfish obligate air breathers? Some evidence from radio telemetry
Item type: Journal Article • Journal: African Zoology • Authors: C. M. Mlewa --- Department of Fisheries, Kenya J. M. Green --- Department of Biology, Canada A1B 3X9 R. Dunbrack --- Department of Biology, Canada A1B 3X9Laboratory studies have resulted in classification of the marbled African lungfish, Protopterus aethiopicus, as an obligate air-breather. However, there have been no investigations of the extent of dependence on aerial respiration by this species in the wild. We used radio... -
Saldanha Bay, South Africa II: estimating bay productivity
Item type: Journal Article • Journal: African Journal of Marine Science • Authors: GC Pitcher --- Branch: Fisheries Management, Department of Agriculture, Forestry and Fisheries, South Africa ME Smith --- Marine Remote Sensing Unit, Department of Oceanography, South Africa TA Probyn --- Branch: Fisheries Management, Department of Agriculture, Forestry and Fisheries, South AfricaSaldanha Bay is a narrow-mouth bay on the west coast of South Africa linked to the southern Benguela upwelling system. Bay productivity was investigated by use of the conventional light-and-dark bottle oxygen method, and, for comparison, through assimilation of the...