xxii, 179 leaves : ill. ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1975) from the Dept. of Plant Physiology, University of Adelaide

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 82-90). Also available in electronic version.

No description available.

No description available.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

No description available.

No description available.

The effect of the plant regulator Mepiquat chloride (PIXᵀᴹ) (1,1-dimethyl-piperidinium chloride), in the early flowering stage, and combinations with soil and foliar application of fertilizers was investigated through seven field experiments conducted in 1982 and 1983 at three University of Arizona experimental locations. Three upland cotton cultivars (Gossypium hirsutum L.), 'Deltapine 55', '61' and '62' were used. Cotton yield, boll properties, fiber properties, leaf chlorophyll content, plant height, plant partitioning and maturity were investigated. Petiole nitrate, leaf area index (LAI) and LAI interrelationship with yield were also included in this study. The use of PIX resulted in an increase in seed cotton yield and boll weight in one of the experiments, while fiber properties did not show any significant response to either PIX or fertilizers. PIX, however, had the tendency to enhance maturity by about 1 week. Use of PIX reduced plant height in all tested cultivars at all locations. The reduction in plant height ranged from 7 to 28% depending on the cultivar, location and the amount of PIX applied. The chlorophyll a and b content of leaves increased significantly as a result of PIX application in two of four tests, while their ratio decreased. Leaf area index between treatments were not significantly different except at one sampling date. In a regression study, however, yield was found to be related positively to LAI when soil and foliar application of fertilizer were added, while it was negative when PIX was applied. Neither PIX nor BALANCEᵀᴹ (1:18:18:1) application affected plant partitioning nor petiole nitrate concentration at most of the sampling dates.

Experiments were conducted to determine if there was a residual effect of the experimental plant growth regulator Ortho XE-1019, (E)-(P-chlorophenyl)-4,4-dimethyl-2-1,2,4-triazol-l-yl)-l-penten-3-01, remaining in Deltapine 50 and 90 cottonseed obtained at three harvest dates from experiments run at the University of Arizona Marana and Maricopa Agricultural Centers in 1986. Commercial DPL 50 seed were treated with XE-1019 in a second experiment. Several growth characteristics were measured including dry weights after 7 and 12 days. Hypocotyl length was not significantly different between treatments after 12 days of growth, with one exception, nor between dates of harvest for DPL 90 and DPL 50. Other measurements sometimes had statistical differences which were more academic but would be of little consequence in obtaining a satisfactory field stand. A significant reduction of hypocotyl length resulted when seed was directly treated with XE-1019 and would result in poor emergence. Results indicated that the use of XE-1019 as a plant growth regulator on cotton would not have significant residual responses on early seedling growth of Deltapine 90 and Deltapine 50 when the resulting seed are used for planting seed in the next generation.

Cavendish bananas are the most important sub-group of all bananas. They includes more than 30% of the global banana production and almost all bananas exported are of the Cavendish type. This sub-group is also an important food source. Most of the fruit is consumed locally, such that only 35% enters the international market. To meet the regular demand for domestic consumption and market supply there must be a reliable production strategy. The technique of tissue culture is a better option than conventional propagation techniques. However. the high incidence of somaclonal variation among plants derived from tissue culture is a problem for commercial producers. Several factors such as genotype, tissue source, duration in culture, and the tissue culture technique employed, cause somaclonal variation. The impact of plant growth regulators on somaclonal variation was studied on Cavendish banana cv. 'Zelig' obtained from African Biotechnologies Ltd., South Africa. In vitro grown plants at the 4th multiplication cycle were supplied for the investigation. The first component of the investigation dealt with the effect of types of plant growth regulators. Combinations of the auxins IAA, IBA and NAA with the cytokinins BA and TDZ were used to culture the plants for ten multiplication cycles. Plants were then randomly selected to collect leaf material for DNA extraction and RAPD analysis. The second aim of this study was to investigate the effect of the cytokinin BA on plantlets subcultured over 5-10 multiplication cycles. The auxin IAA at the concentration of 2 mgl-1 was combined with BA at concentrations of 2.5, 5.0 and 7.5 mgl-1. Plants were analyzed at each level of subculture from the 5th to the 10th cycle for respective cytokinin concentrations. Plants were then randomly selected for the collection of leaf material for DNA extraction and RAPD analysis. DNA was extracted from leaf tissue of in vitro grown plants using a modified CTAB extraction procedure. DNA amplification products were scored for the presence and absence of bands in a particular locus. Results were clustered according to their similarities. The relationship between multiplication rate and variation was assessed using correlation analysis. Results of the investigation showed that treatments with higher multiplication rates produced higher rates of variation. A variation rate of 55% was recorded for treatments containing IAA and BA. A higher rate of variation (72%) was identified in the treatment with IAA (2mgl-1) plus BA (7.5 mgl-1) over 10 cycles. In all cases the dwarf off-type was the most common type of variant obtained, contributing 87.7% of the total amount of variation. The dwarf specific marker (OPJ-041500) reported previously in Williams Cavendish was identified in cv. 'Zelig' in this study. Another band similar in size was amplified by primer OPC-15 and named OPC-151500 . This band consistently appeared in all the normal plants and was absent in all the dwarf types and hence could be used as a dwarf specific marker. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.