Bibliography: leaves 172-197. / xvii, 197 leaves : ill. (chiefly col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil and Water, 2002?

Most tomato cultivars used for commercial food production are imported into South Africa. Optimal growing conditions for these specific cultivars need to be determined, as wrong cultivar choices can lead to great financial losses. Lack of information on selecting well-performing cultivars may lead to lower yield or unacceptable fruit quality. Information on the performance of tomato cultivars under South African conditions, utilizing plastic tunnels or shadenet structures under soilless cultivation is still very limited. Soilless cultivation of vegetables is becoming a preferable over in-soil cultivation due to the improved yield and quality of produce, efficient water and nutrients usage by the crop; furthermore, the grower can regulate nutrient solution, electrical conductivity and pH of the nutrient solution. To identify the optimal system for growing tomatoes hydroponically, the performance of four tomato cultivars (‘FA593’, ‘Miramar’, ‘FiveOFive’ and ‘Malory’) under different growing conditions was evaluated: directly planted in soil under 40% shadenet with drip irrigation, a closed hydroponic system under 40% shadenet, an open bag system under 40% shadenet, or an open-bag system in a temperature controlled as well as a non-temperature controlled tunnel. The study revealed that ‘Miramar’ performed better than the other cultivars in all production systems, with the exception of soil cultivation where there were no differences amongst the four cultivars. Fruit cracking was found to be directly correlated with fruit size, as the large-sized cultivars ‘Malory’ and ‘FA593’ were more susceptible than the other two cultivars. Plants grown under shadenet were prone to fruit cracking and raincheck as well as early blight. Higher yields were obtained when plants were produced in the open bag system under temperature controlled conditions and in the closed system under shadenet. Growing tomatoes in the non-temperature controlled tunnel resulted in high incidences of fruit cracking, poor yield and pre-mature fruit ripening probably due to high and fluctuating temperatures under such conditions. The average marketable yield was 88% and 59% of the total yield in the temperature controlled and non-temperature controlled tunnels, respectively. A further experiment was carried out to improve yield and quality of tunnel tomatoes using beneficial micro-organisms, i.e., arbuscular mycorrhiza fungi (AMF) at different nutrient concentrations. Tomato seedlings were treated with Mycoroot™ containing four mycorrhiza species (Glomus etunicatum, Paraglomus occultum, Glomus clarum and Glomus mossea) at transplanting and subsequently transferred to either a temperature controlled or a non-temperature controlled tunnel under the recommended (100%) or reduced (75 and 50%) nutrient concentrations. Sawdust was used as a growing medium in this experiment. Application of AMF neither enhanced plant growth, yield, nor fruit mineral nutrient concentrations; although fruit Mn and Zn concentrations in the temperature controlled tunnel increased significantly following AMF application. Plants grown in the non-temperature controlled tunnel had significantly poorer plant growth, and lower yield and lower fruit mineral concentrations, compared with fruit from plants in the temperature controlled tunnel. Tomato plants in the non-temperature controlled tunnel had higher levels of micro-elements in leaf tissue, compared with those in the temperature controlled tunnel. The highest yields were obtained from plants fertigated with 75% of the recommended nutrient concentration, as compared with the 100 and 50% nutrient concentrations. When coir was subsequently used as the growing medium, Mycoroot™ applied at seeding and transplanting did not enhance mycorrhizal colonization or fruit quality. Growing tomatoes under reduced nutrient supply reduced the total soluble solids in the juice of the fruit, but improved total and marketable yield, as well as the number of marketable fruit. This effect was more substantial in the temperature controlled than in the non-temperature controlled tunnel. Fruit firmness and leaf chlorophyll concentrations were significantly higher in plants grown in the temperature controlled tunnel. Growing tomatoes in sawdust improved the leaf Mn and Ca concentration over that of tomato plants grown in coir. Mycorrhizal colonisation did not have a beneficial effect on tomato yield and quality. The study indicated that cultivar selection was important in obtaining the highest yield and quality of tomato using the closed hydroponic system under shadenet and the open bag hydroponic system in the temperature controlled tunnel. Temperature controlled tunnels with a pad–and-fan cooling system are still an effective way of cooling the tunnel environment which resulted in high yield and high quality of tomatoes with a higher fruit mineral content than that obtained under non-temperature controlled conditions where only natural ventilation is relied on. Results also demonstrated that mycorrhizal colonization in soilless condition has limited beneficial effects in allowing for better nutrient uptake and thereby for improved yield and quality of tomatoes. Further studies, including different media, nutrient composition and concentrations, need to be carried out to investigate the possible causes of AMF failure to improve yield, despite good AMF root colonization. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

Asparagus (Asparagus officinalis) is a perennial crop well suited to grow in Quebec. Despite high demand for this crop, asparagus production is declining because of asparagus root rot disease that is caused by Fusarium spp. Phosphorus is one of the most important nutrients for the production of healthy asparagus roots that may resist infection by Fusarium. The objective of this study was to determine the effects of phosphorus (P) applications on asparagus yield and soil microbial parameters. Plots receiving 0 to 200% of the P recommendation, based on the Centre de reference en agriculture et agroalimentaire du Quebec (CRAAQ) guidelines, did not differ significantly (p < 0.05) in first year yield or plant tissue concentrations. However, asparagus receiving no fertilizer had 2 to 3 times higher arbuscular mycorrhizal colonisation of roots than other treatments in May 2003. Fresh marketable yield was negatively correlated to Fusarium incidence (p = 0.0091 r = -0.51) suggesting that plants with higher yields are less susceptible to Fusarium symptoms and that producers should avoid over-harvesting low yielding plants to reduce Fusarium spread in the field. Soil microbial activity was not affected consistently by P fertilizers because of high variability in the field.

Abstract Most plants grow in association with arbuscular mycorrhizal (AM) fungi in their roots forming the so-called AM symbiosis. AM symbiosis is usually beneficial to the host as it improves plant survival and performance. However, AM symbiosis also entails a cost to the plant in terms of the carbon allocated to the fungus. In sexually dimorphic plants, more than one type of individual can be recognised with regard to their sexual expression or gender. The cost of reproduction in these plants will differ in relation to the relative investment in male versus female function, as the female and the male sexual functions incur different costs. This different cost of reproduction may be translated into differences in other plant functions between the sexes as all functions are connected through trade-offs. Therefore, since sexes differ in resource needs and allocation patterns, and AM mediate resource acquisition and allocation patterns through imposing both costs and benefits to the plant, the sexes of dimorphic plant species may possess, at least theoretically, a different relationship with their AM roots symbionts. In this thesis, I have investigated whether the sexes in sexually dimorphic plant species differ in their mycorrhizal relationship, and if so, in which ways. Several plant life history traits were studied in the dioecious species Antennaria dioica and also in the gynodioecious Geranium sylvaticum using greenhouse, common-garden and field experiments. Resource acquisition, resource allocation, and both plant and fungal benefits from AM symbiosis were considered. Mainly beneficial effects of AM symbiosis were observed in both sexes of the two dimorphic plant species for most of the studied plant life history traits. Overall, both partners benefited from the AM association. However, several sex-specific benefits were detected which were not uniformly present in all experiments for any given trait. Moreover, the responses observed in certain life history traits were dependent on both the AM fungal and plant species involved in the symbiosis. Remarkably, plants gained sex-specific benefits from the same species of AM fungi and the fungal benefit differed depending on the sex of the host plant. In addition, mycorrhizal benefits were lost under certain environmental conditions. To summarise, the results obtained in this study highlight the complexity of AM interactions. My results suggest that the plant-mycorrhizal fungus relationship may differ depending on the sex of the host plant. Through sex-specific effects on survival, growth and reproduction of the hosts, AM fungi may play a role in the evolution of the life histories in the studied species. In addition, sex-specific relationships between plants and their mycorrhizal symbionts may have potential important consequences for the population dynamics of the sexual morphs and the coevolution of the mycorrhizal relationship.

La symbiose mycorhizienne à arbuscules (SMA) est le résultat de l'interaction entre les racines de plus de 80% des familles de plantes terrestres et les champignons MA. Divers types de membranes jouent un rôle crucial dans la mise en place et le fonctionnement de la SMA chez l’hôte végétal. Si l’électrophorèse bidimensionnelle (2-DE) reste la méthode la plus couramment utilisée pour des analyses protéomiques quantitatives dans la SMA, elle résout difficilement les protéines membranaires en raison de leur hydrophobicité, leur précipitation au point isoélectrique (pI) et leur faible abondance comparativement aux protéines cytosoliques. Donc peu nombreuses sont les protéines membranaires identifiées comme étant régulées en réponse à la symbiose. Afin d’avoir accès à cette catégorie de protéines et contourner les défauts de la 2-DE, l’application de nouvelles méthodes permet de réaliser des analyses quantitatives avec marquage chimique (comme l’iTRAQ) ou non (label-free). Dans ce contexte, deux méthodes de protéomique quantitative, iTRAQ-OFFGEL-CL-SM/SM et « label-free » 1-DE-CL-SM/SM, sont adoptées dans ce travail visant à identifier et quantifier les variations d’accumulation des protéines microsomales de racines de Medicago truncatula inoculées par Rhizophagus irregularis, préalable indispensable à l’analyse de leur rôle fonctionnel dans la SMA. Un protocole d’extraction donnant accès à des fractions radiculaires enrichies en protéines microsomales nécessaires pour les analyses ultérieures est décrit dans cette étude. En plus de l’analyse quantitative du protéome membranaire en réponse à la SMA, une approche méthodologique a été mise en place afin d’étudier l’impact du marquage iTRAQ sur le pI des peptides. / Arbuscular mycorrhizas (AM) are widespread symbiotic associations between plant roots and AM fungi. Deep membrane alterations are the foremost morphological changes occurring in the host plant in response to AM symbiosis. Two-dimensional gel electrophoresis (2-DE) is the workhorse method in AM proteomics. Membrane proteins are under-represented in 2-DE because of their hydrophobicity, low abundance, and precipitation at their isoelectric point, thereby few are the identified membrane proteins involved in sustaining the AM symbiosis. Membrane proteomics is still challenging due to 2-DE related shortcomings, however latest trends and advancements in mass spectrometry (MS)-based quantitative proteomics offer enormous potential to monitor membrane protein change in abundance in large scale experiments. In the current work microsomal proteins of Medicago truncatula roots inoculated with Rhizophagus irregularis were, for the first time, scrutinised by state-of-the-art MS-based proteomic approaches iTRAQ-OFFGEL-LC-MS/MS and label-free 1-DE-LC-MS/MS. The applied workflows combine two novel proteomic procedures, label-based and -free, targeting an insight view on the membrane proteome changes in AM symbiosis. A subcellular fractionation method is herein described to access the total membrane-associated proteins with sufficient recovery and purity for their subsequent in-depth analysis. In addition to the biological gain by shedding the light on candidate AM-related membrane proteins, a methodological approach was carried out in the present work in order to elucidate the iTRAQ labelling impact on peptide isoelectric points.

Fundamental processes underpinning the biotransformation of coal by fungal biocatalysts have been intensively investigated, however, limited large-scale industrial applications using such systems have been reported. The un-anticipated sporadic growth of Cynodon dactylon on the surface of un-rehabilitated discard coal dumps has been noted and this was found to be coupled with the breakdown of coal into a humic soil-like material in the top 1.5 metres of the dumps. Extensive fungal growth was observed to be associated with the Cynodon dactylon root system and examination of plant roots indicated the presence of mycorrhizal fungi. Analysis of the Cynodon dactylon plant roots around which coal biotransformation was occurring confirmed the presence of arbuscular mycorrhizal colonisation with the species Glomus clarum, Paraglomus occultum, Gigaspora gigantea and Glomus mosseae identified to be associated with the plants. Further molecular characterisation of non-mycorrhizal rhizospheric fungi showed the presence of fungal species with coal-degrading capabilities that most likely played a role in the coal biotransformation observed. The discard coal dump environment was simulated in pot and column studies and coal biotransformation was reproduced, with this process enhanced by the addition of mycorrhizal and non-mycorrhizal rhizospheric fungal inocula to the environment. Mycorrhizal and non-mycorrhizal species in the inoculum were re-isolated from the simulated environment fulfilling a number of Koch’s postulates and indicating a causal role in the biotransformation of coal. An inversion of conventional mycorrhizal colonisation was demonstrated in this system with reduction in extraradicular presence and an increase in intracellular colonisation compared to soil controls. A descriptive model was formulated suggesting a two-part fungal system involving organic carbon and nutrient exchange between the plant, mycorrhizal fungi and non-mycorrhizal coal-degrading rhizospheric fungi ultimately resulting in the biotransformation of coal. The biotransformation observed was comparable to reports of “rock-eating fungi”. Results suggest that the biological degradation of coal in situ with the production of a soil-like substrate could provide a feasible method of discard coal dump rehabilitation as well as provide a humic-rich substrate that can be utilised in further industrial applications.

Soybeans (Glycine max L. Merr.) are a symbiont of two beneficial associations: biological nitrogen fixation (BNF) with Bradyrhizobium japonicum, and arbuscular mycorrhizal fungi (AMF). Within the Northern Great Plains of the USA, iron deficiency chlorosis (IDC) of soybean is a yield-limiting factor. The effects of IDC on BNF and AMF are not well defined. This study was conducted to determine the effects of IDC on BNF and AMF. A laboratory study was performed to compare three methods of measuring ureide-N, a product of BNF in soybeans. Field studies in soybean were performed at three locations at eastern N011h Dakota. The experimental design was a factorial combination of three cultivars and three treatments. The three cultivars, in order of decreasing chlorosis susceptibility, were NuTech NT-0886, Roughrider Genetics RG 607, and Syngenta S01-C9 RR. The three treatments were control, Sorghum bicolor L. companion crop planted with the soybean seed, and FeEDDHA applied with the soybean seed. Chlorosis severity was the greatest and least for the NuTech and Syngenta cultivars, respectively. The FeEDDHA treatment decreased chlorosis severity. Ureide levels were abnormally high in plants severely stunted by JDC. The excess accumulation of ureides in IDC-stunted plants suggests that plant growth was reduced more than the rate of nitrogen fixation. The AMF population \vas at an adequate level at all locations and not affected by cultivar or treatment, in general. In the laboratory study, the Patterson et al. method had greater ureide concentrations due to the non-specific measuring of ammonium compounds compared to the Vogels and Van der Drift and Goos methods. / North Dakota Soybean Council

Thesis (M.Sc.)--University of the Witwatersrand, Faculty of Science, School of Botany, 1991 / The vegetation of the Nylsvley Nature Reserve situated in the Northern Transvaal, South Africa. is a semi·arid savanna dominated by Burkea qfricana and Eragrostis paUensf interspersed with patches of Acacia s_pp.and E, ie/t(lnumni(.ma. The Butkea savanna is established on soil which is naturally low in phosphorus while the A,,;acia savanna is established on soU with higber phosphorus levels. Spnres of vesictdar~arbusculat mycorrhizal (VAM) fungi Were extracted from soil samples by wet 8i:¢ving and sucrose ("mttifugation after which they.· were enumerated .and identified. Thirteen VAM species were isolated from the savanna regions. The population was composed of three Gloltlus spp .• four .4cQulosp()ra spp., one .Gigaspora sp., three Scutel!ispora spp. and tWQ species of uncertain identity. Root samples were cleated. and stained with acidic glycerol·tcypan blue and assessed for mycoufMal colonization. Significant positive correlations were indicated. between spore densities ar.d mycorrhizal root infection. The total 81)01:'e popUlation was negntively correlated wiUlavailuble P, organic C, K. Ca. Mg, and pH. ~'tldividual specles differed markedly from the population as a whole in their bltemctions with.,soil facrots, these wem. examined using linear regressions. The VA;M root colonization as assessed b)! the mycorrhizal % WassigIlfijcant!y negativr1v: (forrelated with P white. the frequency % was. negatively correlated. Wilh P and K. .The inter-relatidhs!;tips 'between the d.ifferentVA1\i ,species and enviro~~eiita1 factors were further explored using prinCipal com'ponent ana,lyt;ls. the population structure and the factors affecting the population ate discussed. ..bltemctions with.,soil facrots, these wem. examined using linear regressions. The VA;M root colonization as assessed b)! the mycorrhizal % WassigIlfijcant!y negativr1v: (forrelated with P white. the frequency % was. negatively correlated. Wilh P and K. .The inter-relatidhs!;tips 'between the d.ifferentVA1\i ,species and enviro~~eiita1 factors were further explored using prinCipal com'ponent ana,lyt;ls. the population structure and the factors affecting the population ate discussed. / MN (2017)

No description available.

Thesis (MSc (Botany and Zoology)--University of Stellenbosch, 2006. / Parts of the West Coast Strandveld and adjacent Succulent Karoo on the arid coast of Namakwaland in the Western Cape of South Africa are subject to surface mining. An understanding of mycorrhizal association of plants in the natural vegetation of this area could contribute to the improvement of post-mining re-vegetation of the area. This study investigated mycorrhizal association of plants in the West Coast Strandveld, and compared mycorrhizal infection rates of soils taken from natural vegetation to soils from post-mined rehabilitated vegetations. The study was divided into two components. In the first component a pot experiment was conducted in the greenhouse to assess vesicular-arbuscular mycorrhiza (AM) infectivity of post-mined rehabilitated areas of Brand se Baai in Namakwa Sands mining areas. Rehabilitated areas used in this study included sites that has been strip mined for heavy minerals and then progressively backfilled with sub-soil sand remaining after mineral extraction (tailings), topsoil and translocated plants in an effort to restore the structure and functional aspects of the mined site to its original (pre-mining) ecosystem. Rehabilitated sites 1 assessed in this study included sites backfilled with: tailings + translocated plants (TP); tailing + topsoil + translocated plants (TSP) and tailings + topsoil only (TS). Natural sites (N) were also assessed to serve as reference points. AM infection was evaluated as percent root colonization on wheat planted as bioassay on sterilised sand and inoculum from rehabilitated sites in the ratio of 3:1 respectively. Results of this study component showed that mycorrhiza infectivity of rehabilitated soils was high on TSP and TS because mining disturbance has been remedied by topsoil with or without translocated plant replacement. The structural and chemical components of topsoil used as rehabilitation material favoured re-establishment of microbial activities. Infectivity was however low on soils rehabilitated with tailings and translocated plants (TP) because this treatment lacked topsoil which is a major source of infective mycorrhizal propagules. Infectivity was also low in soils from undisturbed sites (N) probably high phosphorus concentration or presence of perennial vegetation led to low mycorrhiza infection. Results showed that there was no significant effect of mycorrhiza on plant growth rate, nutrient uptake or carbon cost of mycorrhizal plants when related to non-mycorrhizal plants, instead the biomass production and nutrient contents of plants were determined by chemical properties of treatment soils. The second component of the study investigated presence of mycorrhiza on randomly selected common indigenous species of Aizoaceae, Asparagaceae, Asteraceae, Chenopodiaceae, Fabaceae, Lamiaceae, Mesembryanthemaceae, Restionaceae, families growing on unmined areas of the study site. Total mycorrhiza infection was recorded on 85% of the assessed species with percent infection level ranging from 8% in Atriplex lindleyi and Drosanthemum hispidum to 98% in Salvia lanceolata. Functional mycorrhizal association with arbuscule structures were however only observed on 15% of all species assessed. Low arbuscules infection observed in indigenous species assessed in this study could be associated with the timing of mycorrhiza infection assessment and root competition in the soil. There was no infection observed on four species belonging to Chenopodiaceae, Zygophyllaceae, Sterculiaceae, and Asteraceae families, which represented 15% of all species assessed. Most species belonging to Chenopodiaceae and Zygophyllaceae have been reported as non-mycorrhizal in other studies, absence of mycorrhiza on the remaining three families species observed in this study require further confirmation.