Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1979. / Bibliography: leaves 145-157. / Microfiche. / xii, 157 leaves ill. 29 cm

Copies of author's previously published articles in pocket inside back cover. / Bibliography: leaves 147-160. / xvi, 160 leaves, [6] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis outlines the factors affecting soil strength and structural stability and their interrelationship in salt-affected soils. The objectives of this study are to investigate the influence of clay particles on soil densification and mellowing, the mellowing of compacted soils and soil aggregates as influenced by solution composition, the disaggregation of soils subjected to different sodicities and salinities and its relationship to soil strength and dispersible clay and the effect of organic matter and clay type on aggregation of salt-affected soils. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1996

[Truncated abstract] Eucalyptus occidentalis, a timber species from south Western Australia, is highly salt and waterlogging tolerant. Screening identified genotypes tolerant of high salt concentrations and waterlogging. Tolerance at provenance, family and individual level, and how phenotypic performance under salt and waterlogging was inherited was explored to provide a breeding population. Salt and/or waterlogged screening was carried out under controlled conditions up to extreme salt levels to determine tolerance between genotypes. This tank method was shown to produce repeatable results. Seedlings of 30 families from 9 provenances were used for screening. At low salt concentration (up to 300 mM NaCl), differentiation occurred for some traits but in general there was only a slight reduction in growth under salt, and waterlogging alone was not detrimental. At high salt concentration (550 mM) differentiation occurred among genotypes for all traits. Equivalent genotypes were also planted in field trials at three sites, two with medium (583 - 847 mm) and one with low rainfall (372 - 469 mm), in southern Western Australia. Survival was low (<53%) after 9 months due to an exceptional dry season followed by 3 months waterlogging in Kirkwood (38 - 1360 mSm-1), but was high >89% after 33 months in saline fields in Sandalwindy (96 - 976 mSm-1) and Roberts (88 - 1424 mSm-1). Some families were similarly in high rank for height under saline conditions in controlled and field trials. Height had the highest narrow-sense heritability value, especially under controlled saltwaterlogging (0.85) treatment and 20% selection enabled a gain of 8-14% under controlled conditions and in the field. Leaf production under salt was not an inherited trait. Systems were developed to hasten deployment of selected material. Extended daylength (16 h) and paclobutrazol (1 mg a.i/mm stem circumference) stimulated flowering in 2 year-old plants. Clonal propagation was possible. Grafting success varied from 0-100% depending on scion/rootstock provenances. ... There was only a slight reduction in heterozygosity from species level to provenance and family levels, and two superior genotypes maintained high diversity. v Crossing was possible using one stop pollination of cut immature styles and capsule retention varied from 0-34% and germination rate from 2-96%. Genetic distance between parents was correlated with seed set and offspring fitness. Wider genetic distances increased capsule retention, seed germination and seedling survival. Under 500 mM salt-waterlogging, offspring heights were similar when parental genetic distances were similar. High heritability value for height from ANOVA-REML parental screening was confirmed using parent-offspring regression. Screened superior genotypes, which withstood very high salt concentration, provide a breeding population for further breeding and for plantations under saline regions in low-medium rainfall areas in Western Australia and other parts of the world. These trees provide an economic return in areas where no other plants may survive and an environmental service in potentially reducing waterlogging, salinity and its spread.

Thesis (MScBosb)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Thesis (M. Sc. (Geography))--Rhodes University, 2006.

Three hydrosalinity models of different complexity were evaluated against data from selected citrus orchards in the Lower Coerney River irrigation area. These models were statistically compared with field data, and found to vary in accuracy of output predictions. The simplest model, the LEACHING REQUIREMENT (LR) model, has the lowest data input requirements and produces output predictions that correlate with up to 93% of the variance in measured data. SODICS, which is theoretically more detailed and requires a greater level of detail in input, produces predictions of an accuracy equivalent to the LR model. The PEAK model was assessed in two parts, the PEAKM module simulating soil moisture and soil moisture movement was able to predict variations in moisture up to 99% of the time. The PEAKD module, which predicts solute concentrations was less effective in replicating real world conditions

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Thesis (PhD (Soil Science))--University of Stellenbosch, 2005. / Approximately 45% of apricot tree plantings in South Africa are centered on Montagu, Koo and Barrydale in the Little Karoo. Below average production in this area could be ascribed to the deteriorating water quality of the Breede River and highly saline groundwater from boreholes which provide this area with irrigation water. Profit margins for farmers are such that decreased yields cannot be tolerated. Correct management of low quality water could improve production and net farm income and could decrease irrigation return flow into the river system. The objective of this work was to establish whether international water quality guidelines for apricot are applicable under a different set of climatic conditions for a locally important cultivar and to revise guidelines if necessary for the management of irrigation with saline water. A drainage lysimeter was used to evaluate the effect of saline irrigation on apricot (Prunus armeniaca cultivar Palsteyn) trees over a period of four years at Stellenbosch (S33° 55’; E18° 53’) in the Western Cape.