A quantitative investigation of the absorption of certain cations by whole plants and plant tissues
- Authors: Cresswell, Christopher Frederick
- Date: 1959 , 2014-07-24
- Subjects: Cations -- Absorption and adsorption , Plant tissues
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4262 , http://hdl.handle.net/10962/d1013335
- Description: Introduction: Part 1. Greenhouse studies were conducted to investigate the absorption of sodium, potassium, calcium and magnesium by lemon seedlings. The plants were grown in controlled nutrient solutions and analysis of the plant material was made to determine the relationship between the four cations in the different plant organs. Results of the experiment may be summarized as follows:- The occurrence of leaf burn appeared to be associated with a low calcium content, together with a high sodium, potassium or sodium + potassium content. The development of the seedlings was shown to be markedly influenced by the level of calcium supply and to a much lesser degree by the level of potassium supplied. The concentration of sodium, potassium, calcium and magnesium in the stem and leaf varied with position of the tissues on the main axis. The level of sodium was found to influence the distribution of sodium in the leaves, and the sodium content of the leaf, stem and root tissues gave a good reflection of the level of sodium supplied. The effect of the sodium treatment on the uptake of potassium appeared to be dependent on the calcium content of the tissues. Sodium treatment was found not to affect the leaf calcium content. In the stem and root tissues the calcium content was reduced when the calcium level in the nutrient medium was low, and increased the calcium content of these two tissues at the higher level of calcium supply. The sodium supply was shown to reduce the leaf magnesium only slightly, and its affect on the magnesium content of the stem and root tissues was shown to be dependent on the level of calcium supplied. The potassium content of the leaves, stems and roots increased when the supply of potassium was raised. Increasing the potassium level in the nutrient supply was found to cause a very slight reduction in the sodium content of the leaf, but did not affect the sodium content of the stem and root. Potassium did not affect the calcium content of the leaves and increased the stem calcium when sodium was not present in the nutrient media in high concentrations. In the roots potassium only increase the calcium content at the upper level of calcium supply. The magnesium content of the leaf and stem tissues was reduced as the potassium supply was increased. In the roots the general trend was for the magnesium content to increase when the level of potassium treatment was raised. The calcium content of all the plant parts increased with a rise in the calcium supply, the stem and root tissues having a greater percentage increase than the leaves. The sodium content of the plant tissue was reduced as the level of calcium supply was raised. The leaf potassium content decreased with a higher calcium level of supply. In the stem and roots the potassium content was increased by doubling the calcium supply. The calcium treatment had no influence on the magnesium content of the foliage, but in the stem and root tissues a decrease in magnesium content resulted from an increase in the calcium supply. Part II Potato tuber tissue and carrot root tissue were used as experimental material in the investigation of sodium9 potassium9 and calcium uptake by storage tissue. It was shown that when the tissue disks are transferred from distilled water to a solution of salts there is a rapid initial uptake of cation which is neither particularly selective, nor related to metabolism, but dependent on the external concentration. On the other hand, the prolonged active accumulation of cation exhibits selectivity. Potassium absorption by potato tuber tissue was shown to be stimulated by sodium9 whereas the potassium and calcium absorption by carrot root tissue was shown to be reduced by sodium. Similarly the sodium absorption by the carrot root tissue was reduced by potassium, thus suggesting that the cations compete with one another for the same absorption mechanism.
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- Date Issued: 1959
A study of the biology of the Jameson reservoir near Grahamstown, Cape Province
- Authors: Darbyshire, John Frederick
- Date: 1959
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/6784 , vital:21179
- Description: 1. This thesis is an ecological study of a South African water storage reservoir and it’s tributary streams. 2. A brief description of the reservoir, the surrounding vegetation, superficial geological strata, soils and early history of the reservoir is given in Chapter I. 3. The surrounding vegetation is discussed in some detail in Chapter II. The zonation of the plants and the influence of water upon it are discussed. 4. The results of the regular investigations of the physicochemical environment are presented in Appendix 1 and the salient points noted in Chapter III. 5. The species of algae collected are listed in Appendix 2 and in Chapter IV are discussed in relation to habitat and abundance. 6. The animals are dealt with in a similar manner in Chapter V. Under 'Discussion and Conclusions' in Chapter VI an attempt is made to review the findings and discuss their significance.
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- Date Issued: 1959
A study of the predators and parasites of Planococcus citri (Risso) (Homoptera) on vines in the Western Cape Province, South Africa
- Authors: Whitehead, Vincent Booth
- Date: 1959
- Subjects: Hemiptera , Parasites , Insect pests -- Biological control , Grapes -- Diseases and pests
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5896 , http://hdl.handle.net/10962/d1013425
- Description: [Introduction] In the Western Cape Province the mealybug, Planococcus citri (Risso), was first reported on vines in 1930 by Joubert (1943a). By 1935 this mealybug had spread to the Hex River Valley, and subsequently to all the main table grape producing areas of the Western Cape Province. At present Pl. citri is the most important insect pest of the table grape industry and can, if not effectively controlled, result in a loss of at least five per cent of the export table grape crop (Kriegler, 1954). Some preliminary work on the natural enemies of Pl. citri on vines was carried out by Stubbings in 1948, but no further work of this nature has been undertaken in this area since then. The fact that the natural enemies can be an effective check to this mealybug on vines in the Western Cape Province has been known for a number of years (Potgieter, 1937; Hattingh, 1943; Joubert, 1943a; Myburgh, 1951). The present work is an attempt to obtain some basic knowlege of the population fluctuations of the insects concerned in this biological control. Surveys undertaken have shown that there is a complex of primary, secondary and possibly tertiary Hynenopterous parasites associated with Pl. citri. The presence of hyperparasites reduces the efficiency of the primary parasitic Hymenoptera. The usefulness of these primary parasites is further reduced as they only occur in effective numbers for a short period of the year. On the other hand, although attacked by some parasites, the numerous coccinellids found preying on Pl. citri are of more importance in reducing the mealybug populations, as they are present on the vines in effective numbers for the greater part of the year.
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- Date Issued: 1959
The solubility of mercurous chloride in water at 25°C
- Authors: Clur, Dennis Alwin
- Date: 1959
- Subjects: Mercury compounds -- Solubility , Mercuric chloride
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4522 , http://hdl.handle.net/10962/d1014705
- Description: [From Introduction]. In 1955, Dry and Gledhill, both formerly of this Department, published their paper on the Solubility of Mercurous Chloride in Water at 25°0, and it was originally intended that this thesis should be an extension of the study to cover the temperature range from 5 t o 55°0. A preliminary investigation at 25°0, however, failed to yield results which were consistent with their findings, even though their apparatus and experimental technique were used. In an effort to resolve these difficulties their method of saturating the calomel in the conductance cell was thoroughly investigated, and as this procedure was found to be responsible, it was necessary to evolve an entirely new approach. The technique finally adopted was to saturate the mercurous chloride solutions by mechanical stirring in siliconed vessels and to carry out the conductance, pH, and total mercury concentration measurements on the filter ed solution. This method gave good results, and was free from the many extrapolations prevalent in the original procedure.
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- Date Issued: 1959
The sorption of Hydrochloric Acid and Potassium Hydroxide by mohair and wool
- Authors: Bamford, Graeme Reginald Ernest
- Date: 1959
- Subjects: Hydrochloric acid -- Absorption and adsorption , Hydroxides -- Absorption and adsorption , Wool , Mohair
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4452 , http://hdl.handle.net/10962/d1009503
- Description: The main object of the present investigation has been to establish a titration curve for mohair keratin and to compare it with similar data for wool, to determine whether the differences in physical and chemical properties could be attributed in any way to the acidic and basic character of these fibres. As shown in subsequent discussion such measurements provide extremely useful information regarding the chemical structure of proteins in general, and in the technical fields involving processes such as wool scouring, carbonizing and dyeing. The study has been extended to include certain modified wools, i.e. photochemically damaged, and oxidized keratin. The most successful contribution to the titration data of wool keratin is the work of Steinhardt and Harris and subsequent authors have tended to adopt their procedures without modification. In the present study attempts have been made to obtain a clearer understanding of the fundamental processes. New techniques and analytical methods have been introduced to improve the accuracy of the measurements.
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- Date Issued: 1959
The thermal decomposition of irradiated silver permanganate
- Authors: Sole, Michael John
- Date: 1959
- Subjects: Decomposition (Chemistry) , Irradiation , Permanganates , Silver compounds , Metals -- Thermal properties
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4502 , http://hdl.handle.net/10962/d1013265
- Description: The thermal decomposition of silver permanganate, pre-irradiated in BEPO and in a ⁶°C₀ Ϫ 'hot spot' has been investigated in the temperature range 100 - 125°C. The results are similar to those for irradiated KMn0₄ and the mechanism proposed for the latter is again suggested. The activation energy for the migration of point defects over the induction period is 1.03 ev. The decompositions of unirradiated and irradiated crystals differ in that the latter undergo physical disintegration over the acceleratory period. X-ray studies immediately prior to disintegration show strain and fragmentation in the irradiated crystal. An explanation involving the annealing of point defects at dislocation is advanced to explain the changes produced in the p/t plots with increased dosage, and fixed decomposition temperature. Summary, p. 94.
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- Date Issued: 1959